土木工程毕业设计外文翻译
土木工程毕业设计外文翻译原文+翻译
The bridge crack produced the reason to simply analyseIn recent years, the traffic capital construction of our province gets swift and violent development, all parts have built a large number of concrete bridges. In the course of building and using in the bridge, relevant to influence project quality lead of common occurrence report that bridge collapse even because the crack appears The concrete can be said to " often have illness coming on " while fracturing and " frequently-occurring disease ", often perplex bridge engineers and technicians. In fact , if take certain design and construction measure, a lot of cracks can be overcome and controlled. For strengthen understanding of concrete bridge crack further, is it prevent project from endanger larger crack to try one's best, this text make an more overall analysis , summary to concrete kind and reason of production , bridge of crack as much as possible, in order to design , construct and find out the feasible method which control the crack , get the result of taking precautions against Yu WeiRan.Concrete bridge crack kind, origin cause of formation In fact, the origin cause of formation of the concrete structure crack is complicated and various, even many kinds of factors influence each other , but every crack has its one or several kinds of main reasons produced . The kind of the concrete bridge crack, on its reason to produce, can roughly divide several kinds as follows :(1) load the crack caused Concrete in routine quiet .Is it load to move and crack that produce claim to load the crack under the times of stress bridge, summing up has direct stress cracks , two kinds stress crack onces mainly. Direct stress crack refer to outside load direct crack that stress produce that cause. The reason why the crack produces is as follows, 1, Design the stage of calculating , does not calculate or leaks and calculates partly while calculating in structure; Calculate the model is unreasonable; The structure is supposed and accorded with by strength actually by strength ; Load and calculate or leak and calculate few; Internal force and matching the mistake in computation of muscle; Safety coefficient of structure is not enough. Do not consider the possibility that construct at the time of the structural design; It is insufficientto design the section; It is simply little and assigning the mistake for reinforcing bar to set up; Structure rigidity is insufficient; Construct and deal with improperly; The design drawing can not be explained clearly etc.. 2, Construction stage, does not pile up and construct the machines , material limiting ; Is it prefabricate structure structure receive strength characteristic , stand up , is it hang , transport , install to get up at will to understand; Construct not according to the design drawing, alter the construction order of the structure without authorization , change the structure and receive the strength mode; Do not do the tired intensity checking computations under machine vibration and wait to the structure . 3, Using stage, the heavy-duty vehicle which goes beyond the design load passes the bridge; Receive the contact , striking of the vehicle , shipping; Strong wind , heavy snow , earthquake happen , explode etc.. Stress crack once means the stress of secondary caused by loading outside produces the crack. The reason why the crack produces is as follows, 1, In design outside load function , because actual working state and routine , structure of thing calculate have discrepancy or is it consider to calculate, thus cause stress once to cause the structure to fracture in some position. Two is it join bridge arch foot is it is it assign " X " shape reinforcing bar , cut down this place way , section of size design and cut with scissors at the same time to adopt often to design to cut with scissors, theory calculate place this can store curved square in , but reality should is it can resist curved still to cut with scissors, so that present the crack and cause the reinforcing bar corrosion. 2, Bridge structure is it dig trough , turn on hole , set up ox leg ,etc. to need often, difficult to use a accurate one diagrammatic to is it is it calculate to imitate to go on in calculating in routine, set up and receive the strength reinforcing bar in general foundation experience. Studies have shown , after being dug the hole by the strength component , it will produce the diffraction phenomenon that strength flows, intensive near the hole in a utensil, produced the enormous stress to concentrate. In long to step prestressing force of the continuous roof beam , often block the steel bunch according to the needs of section internal force in stepping, set up the anchor head, but can often see the crack in the anchor firm section adjacent place. So if deal with improper, in corner or component form sudden change office , block place to be easy to appear crack strengthreinforcing bar of structure the. In the actual project, stress crack once produced the most common reason which loads the crack. Stress crack once belong to one more piece of nature of drawing , splitting off , shearing. Stress crack once is loaded and caused, only seldom calculate according to the routine too, but with modern to calculate constant perfection of means, times of stress crack to can accomplish reasonable checking computations too. For example to such stresses 2 times of producing as prestressing force , creeping ,etc., department's finite element procedure calculates levels pole correctly now, but more difficult 40 years ago. In the design, should pay attention to avoiding structure sudden change (or section sudden change), when it is unable to avoid , should do part deal with , corner for instance, make round horn , sudden change office make into the gradation zone transition, is it is it mix muscle to construct to strengthen at the same time, corner mix again oblique to reinforcing bar , as to large hole in a utensil can set up protecting in the perimeter at the terms of having angle steel. Load the crack characteristic in accordance with loading differently and presenting different characteristics differently. The crack appear person who draw more, the cutting area or the serious position of vibration. Must point out , is it get up cover or have along keep into short crack of direction to appear person who press, often the structure reaches the sign of bearing the weight of strength limit, it is an omen that the structure is destroyed, its reason is often that sectional size is partial and small. Receive the strength way differently according to the structure, the crack characteristic produced is as follows: 1, The centre is drawn. The crack runs through the component cross section , the interval is equal on the whole , and is perpendicular to receiving the strength direction. While adopting the whorl reinforcing bar , lie in the second-class crack near the reinforcing bar between the cracks. 2, The centre is pressed. It is parallel on the short and dense parallel crack which receive the strength direction to appear along the component. 3, Receive curved. Most near the large section from border is it appear and draw into direction vertical crack to begin person who draw curved square, and develop toward neutralization axle gradually. While adopting the whorl reinforcing bar , can see shorter second-class crack among the cracks. When the structure matches muscles less, there are few but wide cracks, fragility destruction may take place in thestructure 4, Pressed big and partial. Heavy to press and mix person who draw muscle a less one light to pigeonhole into the component while being partial while being partial, similar to receiving the curved component. 5, Pressed small and partial. Small to press and mix person who draw muscle a more one heavy to pigeonhole into the component while being partial while being partial, similar to the centre and pressed the component. 6, Cut. Press obliquly when the hoop muscle is too dense and destroy, the oblique crack which is greater than 45?? direction appears along the belly of roof beam end; Is it is it is it destroy to press to cut to happen when the hoop muscle is proper, underpart is it invite 45?? direction parallel oblique crack each other to appear along roof beam end. 7, Sprained. Component one side belly appear many direction oblique crack, 45?? of treaty, first, and to launch with spiral direction being adjoint. 8, Washed and cut. 4 side is it invite 45?? direction inclined plane draw and split to take place along column cap board, form the tangent plane of washing. 9, Some and is pressed. Some to appear person who press direction roughly parallel large short cracks with pressure.(2) crack caused in temperature changeThe concrete has nature of expanding with heat and contract with cold, look on as the external environment condition or the structure temperature changes, concrete take place out of shape, if out of shape to restrain from, produce the stress in the structure, produce the temperature crack promptly when exceeding concrete tensile strength in stress. In some being heavy to step foot-path among the bridge , temperature stress can is it go beyond living year stress even to reach. The temperature crack distinguishes the main characteristic of other cracks will be varied with temperature and expanded or closed up. The main factor is as follows, to cause temperature and change 1, Annual difference in temperature. Temperature is changing constantly in four seasons in one year, but change relatively slowly, the impact on structure of the bridge is mainly the vertical displacement which causes the bridge, can prop up seat move or set up flexible mound ,etc. not to construct measure coordinate , through bridge floor expansion joint generally, can cause temperature crack only when the displacement of the structure is limited, for example arched bridge , just bridge etc. The annual difference in temperature of our country generally changes therange with the conduct of the average temperature in the moon of January and July. Considering the creep characteristic of the concrete, the elastic mould amount of concrete should be considered rolling over and reducing when the internal force of the annual difference in temperature is calculated. 2, Rizhao. After being tanned by the sun by the sun to the side of bridge panel , the girder or the pier, temperature is obviously higher than other position, the temperature gradient is presented and distributed by the line shape . Because of restrain oneself function, cause part draw stress to be relatively heavy, the crack appears. Rizhao and following to is it cause structure common reason most , temperature of crack to lower the temperature suddenly 3, Lower the temperature suddenly. Fall heavy rain , cold air attack , sunset ,etc. can cause structure surface temperature suddenly dropped suddenly, but because inside temperature change relatively slow producing temperature gradient. Rizhao and lower the temperature internal force can adopt design specification or consult real bridge materials go on when calculating suddenly, concrete elastic mould amount does not consider converting into and reducing 4, Heat of hydration. Appear in the course of constructing, the large volume concrete (thickness exceeds 2. 0), after building because cement water send out heat, cause inside very much high temperature, the internal and external difference in temperature is too large, cause the surface to appear in the crack. Should according to actual conditions in constructing, is it choose heat of hydration low cement variety to try one's best, limit cement unit's consumption, reduce the aggregate and enter the temperature of the mould , reduce the internal and external difference in temperature, and lower the temperature slowly , can adopt the circulation cooling system to carry on the inside to dispel the heat in case of necessity, or adopt the thin layer and build it in succession in order to accelerate dispelling the heat. 5, The construction measure is improper at the time of steam maintenance or the winter construction , the concrete is sudden and cold and sudden and hot, internal and external temperature is uneven , apt to appear in the crack. 6, Prefabricate T roof beam horizontal baffle when the installation , prop up seat bury stencil plate with transfer flat stencil plate when welding in advance, if weld measure to be improper, iron pieces of nearby concrete easy to is it fracture to burn. Adopt electric heat piece draw law piece draw prestressing force at the component ,prestressing force steel temperature can rise to 350 degrees Centigrade , the concrete component is apt to fracture. Experimental study indicates , are caused the intensity of concrete that the high temperature burns to obviously reduce with rising of temperature by such reasons as the fire ,etc., glueing forming the decline thereupon of strength of reinforcing bar and concrete, tensile strength drop by 50% after concrete temperature reaches 300 degrees Centigrade, compression strength drops by 60%, glueing the strength of forming to drop by 80% of only round reinforcing bar and concrete; Because heat, concrete body dissociate ink evaporate and can produce and shrink sharply in a large amount(3) shrink the crack causedIn the actual project, it is the most common because concrete shrinks the crack caused. Shrink kind in concrete, plasticity shrink is it it shrinks (is it contract to do ) to be the main reason that the volume of concrete out of shape happens to shrink, shrink spontaneously in addition and the char shrink. Plasticity shrink. About 4 hours after it is built that in the course of constructing , concrete happens, the cement water response is fierce at this moment, the strand takes shape gradually, secrete water and moisture to evaporate sharply, the concrete desiccates and shrinks, it is at the same time conduct oneself with dignity not sinking because aggregate,so when harden concrete yet,it call plasticity shrink. The plasticity shrink producing amount grade is very big, can be up to about 1%. If stopped by the reinforcing bar while the aggregate sinks, form the crack along the reinforcing bar direction. If web , roof beam of T and roof beam of case and carry baseplate hand over office in component vertical to become sectional place, because sink too really to superficial obeying the web direction crack will happen evenly before hardenning. For reducing concrete plasticity shrink,it should control by water dust when being construct than,last long-time mixing, unloading should not too quick, is it is it take closely knit to smash to shake, vertical to become sectional place should divide layer build. Shrink and shrink (do and contract). After the concrete is formed hard , as the top layer moisture is evaporated progressively , the humidity is reduced progressively , the volume of concrete is reduced, is called and shrunk to shrink (do and contract). Because concrete top layermoisture loss soon, it is slow for inside to lose, produce surface shrink heavy , inside shrink a light one even to shrink, it is out of shape to restrain from by the inside concrete for surface to shrink, cause the surface concrete to bear pulling force, when the surface concrete bears pulling force to exceed its tensile strength, produce and shrink the crack. The concrete hardens after-contraction to just shrink and shrink mainly .Such as mix muscle rate heavy component (exceed 3% ), between reinforcing bar and more obvious restraints relatively that concrete shrink, the concrete surface is apt to appear in the full of cracks crackle. Shrink spontaneously. Spontaneous to it shrinks to be concrete in the course of hardenning , cement and water take place ink react, the shrink with have nothing to do by external humidity, and can positive (whether shrink, such as ordinary portland cement concrete), can negative too (whether expand, such as concrete, concrete of slag cement and cement of fly ash). The char shrinks. Between carbon dioxide and hyrate of cement of atmosphere take place out of shape shrink that chemical reaction cause. The char shrinks and could happen only about 50% of humidity, and accelerate with increase of the density of the carbon dioxide. The char shrinks and seldom calculates . The characteristic that the concrete shrinks the crack is that the majority belongs to the surface crack, the crack is relatively detailed in width , and criss-cross, become the full of cracks form , the form does not have any law . Studies have shown , influence concrete shrink main factor of crack as follows, 1, Variety of cement , grade and consumption. Slag cement , quick-hardening cement , low-heat cement concrete contractivity are relatively high, ordinary cement , volcanic ash cement , alumina cement concrete contractivity are relatively low. Cement grade low in addition, unit volume consumption heavy rubing detailed degree heavy, then the concrete shrinks the more greatly, and shrink time is the longer. For example, in order to improve the intensity of the concrete , often adopt and increase the cement consumption method by force while constructing, the result shrinks the stress to obviously strengthen . 2, Variety of aggregate. Such absorbing water rates as the quartz , limestone , cloud rock , granite , feldspar ,etc. are smaller, contractivity is relatively low in the aggregate; And such absorbing water rates as the sandstone , slate , angle amphibolite ,etc. are greater, contractivity is relatively high. Aggregate grains of foot-path heavy to shrink light inaddition, water content big to shrink the larger. 3, Water gray than. The heavier water consumption is, the higher water and dust are, the concrete shrinks the more greatly. 4, Mix the pharmaceutical outside. It is the better to mix pharmaceutical water-retaining property outside, then the concrete shrinks the smaller. 5, Maintain the method . Water that good maintenance can accelerate the concrete reacts, obtain the intensity of higher concrete. Keep humidity high , low maintaining time to be the longer temperature when maintaining, then the concrete shrinks the smaller. Steam maintain way than maintain way concrete is it take light to shrink naturall. 6, External environment. The humidity is little, the air drying , temperature are high, the wind speed is large in the atmosphere, then the concrete moisture is evaporated fast, the concrete shrinks the faster. 7, Shake and smash the way and time. Machinery shake way of smashing than make firm by ramming or tamping way concrete contractivity take little by hand. Shaking should determine according to mechanical performance to smash time , are generally suitable for 55s / time. It is too short, shake and can not smash closely knit , it is insufficient or not even in intensity to form the concrete; It is too long, cause and divide storey, thick aggregate sinks to the ground floor, the upper strata that the detailed aggregate stays, the intensity is not even , the upper strata incident shrink the crack. And shrink the crack caused to temperature, worthy of constructing the reinforcing bar againing can obviously improve the resisting the splitting of concrete , structure of especially thin wall (thick 200cm of wall ). Mix muscle should is it adopt light diameter reinforcing bar (8 |? construct 14 |? ) to have priority , little interval assign (whether @ 10 construct @ 15cm ) on constructing, the whole section is it mix muscle to be rate unsuitable to be lower than 0 to construct. 3%, can generally adopt 0 . 3%~0. 5%.(4), crack that causes out of shape of plinth of the groundBecause foundation vertical to even to subside or horizontal direction displacement, make the structure produce the additional stress, go beyond resisting the ability of drawing of concrete structure, cause the structure to fracture. The even main reason that subside of the foundation is as follows, 1, Reconnoitres the precision and is not enough for , test the materials inaccuratly in geology. Designing, constructing without fully grasping the geological situation, this is the main reason that cause the ground not to subside evenly .Such as hills area or bridge, district of mountain ridge,, hole interval to be too far when reconnoitring, and ground rise and fall big the rock, reconnoitring the report can't fully reflect the real geological situation . 2, The geological difference of the ground is too large. Building it in the bridge of the valley of the ditch of mountain area, geology of the stream place and place on the hillside change larger, even there are weak grounds in the stream, because the soil of the ground does not causes and does not subside evenly with the compressing. 3, The structure loads the difference too big. Under the unanimous terms, when every foundation too heavy to load difference in geological situation, may cause evenly to subside, for example high to fill out soil case shape in the middle part of the culvert than to is it take heavy to load both sides, to subside soon heavy than both sides middle part, case is it might fracture to contain 4, The difference of basic type of structure is great. Unite it in the bridge the samly , mix and use and does not expand the foundation and a foundation with the foundation, or adopt a foundation when a foot-path or a long difference is great at the same time , or adopt the foundation of expanding when basis elevation is widely different at the same time , may cause the ground not to subside evenly too 5, Foundation built by stages. In the newly-built bridge near the foundation of original bridge, if the half a bridge about expressway built by stages, the newly-built bridge loads or the foundation causes the soil of the ground to consolidate again while dealing with, may cause and subside the foundation of original bridge greatly 6, The ground is frozen bloatedly. The ground soil of higher moisture content on terms that lower than zero degree expands because of being icy; Once temperature goes up , the frozen soil is melted, the setting of ground. So the ground is icy or melts causes and does not subside evenly . 7, Bridge foundation put on body, cave with stalactites and stalagmites, activity fault,etc. of coming down at the bad geology, may cause and does not subside evenly . 8, After the bridge is built up , the condition change of original ground . After most natural grounds and artificial grounds are soaked with water, especially usually fill out such soil of special ground as the soil , loess , expanding in the land ,etc., soil body intensity meet water drop, compress out of shape to strengthen. In the soft soil ground , season causes the water table to drop to draw water or arid artificially, the ground soil layer consolidates and sinks again,reduce the buoyancy on the foundation at the same time , shouldering the obstruction of rubing to increase, the foundation is carried on one's shoulder or back and strengthened .Some bridge foundation is it put too shallow to bury, erode , is it dig to wash flood, the foundation might be moved. Ground load change of terms, bridge nearby is it is it abolish square , grit ,etc. in a large amount to put to pile with cave in , landslide ,etc. reason for instance, it is out of shape that the bridge location range soil layer may be compressed again. So, the condition of original ground change while using may cause and does not subside evenly Produce the structure thing of horizontal thrust to arched bridge ,etc., it is the main reason that horizontal displacement crack emerges to destroy the original geological condition when to that it is unreasonable to grasp incompletely , design and construct in the geological situation.桥梁裂缝产生原因浅析近年来，我省交通基础建设得到迅猛发展，各地建立了大量的混凝土桥梁。
土木工程专业毕业设计- 外文翻译
Structure in Design of ArchitectureAnd Structural Material专业：土木工程学生：指导老师：We have and the architects must deal with the spatial aspect of activity, physical, and symbolic needs in such a way that overall performance integrity is assured. Hence, he or she well wants to think of evolving a building environment as a total system of interacting and space forming subsystems. Is represents a complex challenge, and to meet it the architect will need a hierarchic design process that provides at least three levels of feedback thinking: schematic, preliminary, and final.Such a hierarchy is necessary if he or she is to avoid being confused , at conceptual stages of design thinking ,by the myriad detail issues that can distract attention from more basic considerations .In fact , we can say that an architect’s ability to distinguish the more basic form the more detailed issues is essential to his success as a designer .The object of the schematic feed back level is to generate and evaluate overall site-plan, activity-interaction, and building-configuration options .To do so the architect must be able to focus on the interaction of the basic attributes of the site context, the spatial organization, and the symbolism as determinants of physical form. This means that ,in schematic terms ,the architect may first conceive and model a building design as an organizational abstraction of essential performance-space in teractions.Then he or she may explore the overall space-form implications of the abstraction. As an actual building configuration option begins to emerge, it will be modified to include consideration for basic site conditions.At the schematic stage, it would also be helpful if the designer could visualize his or her options for achieving overall structural integrity and consider the constructive feasibility and economic of his or her scheme .But this will require that the architect and/or a consultant be able to conceptualize total-system structural options in terms of elemental detail .Such overall thinking can be easily fed back to improve the space-form scheme.At the preliminary level, the architect’s emphasis will shift to the elaboration of his or her more promising schematic design options .Here the architect’s structural needs will shift to approximate design of specific subsystem options. At this stage the total structural scheme is developed to a middle level of specificity by focusing on identification and design of major subsystems to the extent that their key geometric, component, and interactive properties are established .Basic subsystem interaction and design conflicts can thus be identified and resolved in the context of total-system objectives. Consultants can play a significant part in this effort; these preliminary-level decisions may also result in feedback that calls for refinement or even major change in schematic concepts.When the designer and the client are satisfied with the feasibility of a design proposal at the preliminary level, it means that the basic problems of overall design are solved and details arenot likely to produce major change .The focus shifts again ,and the design process moves into the final level .At this stage the emphasis will be on the detailed development of all subsystem specifics . Here the role of specialists from various fields, including structural engineering, is much larger, since all detail of the preliminary design must be worked out. Decisions made at this level may produce feedback into Level II that will result in changes. However, if Levels I and II are handled with insight, the relationship between the overall decisions, made at the schematic and preliminary levels, and the specifics of the final level should be such that gross redesign is not in question, Rather, the entire process should be one of moving in an evolutionary fashion from creation and refinement (or modification) of the more general properties of a total-system design concept, to the fleshing out of requisite elements and details.To summarize: At Level I, the architect must first establish, in conceptual terms, the overall space-form feasibility of basic schematic options. At this stage, collaboration with specialists can be helpful, but only if in the form of overall thinking. At Level II, the architect must be able to identify the major subsystem requirements implied by the scheme and substantial their interactive feasibility by approximating key component properties .That is, the properties of major subsystems need be worked out only in sufficient depth to very the inherent compatibility of their basic form-related and behavioral interaction . This will mean a somewhat more specific form of collaboration with specialists then that in level I .At level III ,the architect and the specific form of collaboration with specialists then that providing for all of the elemental design specifics required to produce biddable construction documents .Of course this success comes from the development of the Structural Material.The principal construction materials of earlier times were wood and masonry brick, stone, or tile, and similar materials. The courses or layers were bound together with mortar or bitumen, a tar like substance, or some other binding agent. The Greeks and Romans sometimes used iron rods or claps to strengthen their building. The columns of the Parthenon in Athens, for example, have holes drilled in them for iron bars that have now rusted away. The Romans also used a natural cement called puzzling, made from volcanic ash, that became as hard as stone under water.Both steel and cement, the two most important construction materials of modern times, were introduced in the nineteenth century. Steel, basically an alloy of iron and a small amount of carbon had been made up to that time by a laborious process that restricted it to such special uses as sword blades. After the invention of the Bessemer process in 1856, steel was available in large quantities at low prices. The enormous advantage of steel is its tensile force which, as we have seen, tends to pull apart many materials. New alloys have further, which is a tendency for it to weaken as a result of continual changes in stress.Modern cement, called Portland cement, was invented in 1824. It is a mixture of limestone and clay, which is heated and then ground into a power. It is mixed at or near the construction site with sand, aggregate small stones, crushed rock, or gravel, and water to make concrete. Different proportions of the ingredients produce concrete with different strength and weight. Concrete is very versatile; it can be poured, pumped, or even sprayed into all kinds of shapes. And whereas steel has great tensile strength, concrete has great strength under compression. Thus, the two substances complement each other.They also complement each other in another way: they have almost the same rate ofcontraction and expansion. They therefore can work together in situations where both compression and tension are factors. Steel rods are embedded in concrete to make reinforced concrete in concrete beams or structures where tensions will develop. Concrete and steel also form such a strong bond─ the force that unites them─ that the steel cannot slip within the concrete. Still another advantage is that steel does not rust in concrete. Acid corrodes steel, whereas concrete has an alkaline chemical reaction, the opposite of acid.The adoption of structural steel and reinforced concrete caused major changes in traditional construction practices. It was no longer necessary to use thick walls of stone or brick for multistory buildings, and it became much simpler to build fire-resistant floors. Both these changes served to reduce the cost of construction. It also became possible to erect buildings with greater heights and longer spans.Since the weight of modern structures is carried by the steel or concrete frame, the walls do not support the building. They have become curtain walls, which keep out the weather and let in light. In the earlier steel or concrete frame building, the curtain walls were generally made of masonry; they had the solid look of bearing walls. Today, however, curtain walls are often made of lightweight materials such as glass, aluminum, or plastic, in various combinations.Another advance in steel construction is the method of fastening together the beams. For many years the standard method was riveting. A rivet is a bolt with a head that looks like a blunt screw without threads. It is heated, placed in holes through the pieces of steel, and a second head is formed at the other end by hammering it to hold it in place. Riveting has now largely been replaced by welding, the joining together of pieces of steel by melting a steel material between them under high heat.Priestess’s concrete is an improved form of reinforcement. Steel r ods are bent into the shapes to give them the necessary degree of tensile strengths. They are then used to priestess concrete, usually by one of two different methods. The first is to leave channels in a concrete beam that correspond to the shapes of the steel rods. When the rods are run through the channels, they are then bonded to the concrete by filling the channels with grout, a thin mortar or binding agent. In the other (and more common) method, the priestesses steel rods are placed in the lower part of a form that corresponds to the shape of the finished structure, and the concrete is poured around them. Priestess’s concrete uses less steel and less concrete. Because it is a highly desirable material.Progressed concrete has made it possible to develop buildings with unusual shapes, like some of the modern, sports arenas, with large spaces unbroken by any obstructing supports. The uses for this relatively new structural method are constantly being developed.建筑中的结构设计及建筑材料专业：土木工程学生：指导老师：建筑师必须从一种全局的角度出发去处理建筑设计中应该考虑到的实用活动，物质及象征性的需求。
土木工程毕业设计中英文翻译
土木工程毕业设计中英文翻译附录:中英文翻译英文部分:LOADSLoads that act on structures are usually classified as dead loads or live loads.Dead loads are fixed in location and constant in magnitude throughout the life of the ually the self-weight of a structure is the most important part of the structure and the unit weight of the material.Concrete density2varies from about 90 to 120 pcf (14 to 19 )for lightweight concrete,and is about 145 pcf (23 KN/m2)for normal concrete.In calculating the dead load of structural concrete,usually a 5 pcf (1 KN/m2)increment is included with the weight of the concrete to account for the presence of the KN/mreinforcement.Live loads are loads such as occupancy,snow,wind,or traffic loads,or seismic forces.They may be either fully or partially in place,or not present at all.They may also change in location.Althought it is the responsibility of the engineer to calculate dead loads,live loads are usually specified by local,regional,or national codes and specifications.Typical sources are the publications of the American National Standards Institute,the American Association of StateHighway and Transportation Officials and,for wind loads,the recommendations of the ASCE Task Committee on Wind Forces.Specified live the loads usually include some allowance for overload,and may include measures such as posting of maximum loads will not be exceeded.It is oftern important to distinguish between the specified load,and what is termed the characteristic load,that is,the load that actually is in effect under normal conditions of service,which may be significantly less.In estimating the long-term deflection of a structure,for example,it is the characteristic load that isimportant,not the specified load.The sum of the calculated dead load and the specified live load is called the service load,because this is the maximum load which may reasonably be expected to act during the service resisting is a multiple of the service load.StrengthThe strength of a structure depends on the strength of the materials from which it is made.Minimum material strengths are specified incertain standardized ways.The properties of concrete and its components,the methods of mixing,placing,and curing to obtain the required quality,and the methods for testing,are specified by the American Concrete Insititue(ACI).Included by refrence in the same documentare standards of the American Society for TestingMaterials(ASTM)pertaining to reinforcing and prestressing steels and concrete.Strength also depends on the care with which the structure isbuilt.Member sizes may differ from specified dimensions,reinforcement may be out of position,or poor placement of concrete may result in voids.An important part of the job of the ergineer is to provide proper supervision of construction.Slighting of this responsibility has had disastrous consequences in more than one instance.Structural SafetySafety requires that the strength of a structure be adequate for all loads that may conceivably act on it.If strength could be predicted accurately and if loads were known with equal certainty,then safely could be assured by providing strength just barely in excess of the requirements of the loads.But there are many sources of uncertainty in the estimation of loads as well as in analysis,design,andconstruction.These uncertainties require a safety margin.In recent years engineers have come to realize that the matter of structural safety is probabilistic in nature,and the safety provisions of many current specifications reflect this view.Separate consideration is given to loads and strength.Loadfactors,larger than unity,are applied to the calculated dead loads and estimated or specified service live loads,to obtain factorde loads that the member must just be capable of sustaining at incipient failure.Loadfactors pertaining to different types of loads vary,depending on the degree of uncertainty associated with loads of various types,and with the likelihood of simultaneous occurrence of different loads.Early in the development of prestressed concrete,the goal of prestressing was the complete elimination of concrete ternsile stress at service loads.The concept was that of an entirely new,homogeneous material that woukd remain uncracked and respond elastically up to the maximum anticipated loading.This kind of design,where the limiting tensile stressing,while an alternative approach,in which a certain amount of tensile amount of tensile stress is permitted in the concrete at full service load,is called partial prestressing.There are cases in which it is necessary to avoid all risk of cracking and in which full prestressing is required.Such cases include tanks or reservious where leaks must be avoided,submerged structures or those subject to a highly corrosive envionment where maximum protection of reinforcement must be insured,and structures subject to high frequency repetition of load where faatigue of the reinforcement may be a consideration.However,there are many cses where substantially improved performance,reduced cost,or both may be obtained through the use of a lesser amount of prestress.Full predtressed beams may exhibit an undesirable amount of upward camber because of the eccentric prestressing force,a displacement that is only partially counteracted by the gravity loads producing downward deflection.This tendency isaggrabated by creep in the concrete,which magnigies the upward displacement due to the prestress force,but has little influence on the should heavily prestressed members be overloaded and fail,they may do so in a brittle way,rather than gradually as do beams with a smaller amount of prestress.This is important from the point of view of safety,because suddenfailure without warning is dangeroud,and gives no opportunity for corrective measures to be taken.Furthermore,experience indicates that in many cases improved economy results from the use of a combination of unstressed bar steel and high strength prestressed steel tendons.While tensile stress and possible cracking may be allowed at full service load,it is also recognized that such full service load may be infrequently applied.The typical,or characteristic,load acting is likely to be the dead load plus a small fraction of the specified liveload.Thus a partially predtressed beam may not be subject to tensile stress under the usual conditions of loading.Cracks may from occasionally,when the maximum load is applied,but these will close completely when that load is removed.They may be no more objectionablein prestressed structures than in ordinary reinforced.They may be no more objectionable in prestressed structures than in ordinary reinforced concrete,in which flexural cracks always form.They may be considered a small price for the improvements in performance and economy that are obtained.It has been observed that reinforced concrete is but a special case of prestressed concrete in which the prestressing force is zero.Thebehavior of reinforced and prestressed concrete beams,as the failure load is approached,is essentially the same.The Joint European Committee on Concrete establishes threee classes of prestressed beams.Class 1:Fully prestressed,in which no tensile stress is allowed in the concrete at service load.Class 2:Partially prestressed, in which occasional temporary cracking is permitted under infrequent high loads.Class 3:Partially prestressed,in which there may be permanent cracks provided that their width is suitably limited.The choise of a suitable amount of prestress is governed by avariety of factors.These include thenature of the loading (for exmaple,highway or railroadbridged,storage,ect.),the ratio of live to dead load,the frequency of occurrence of loading may be reversed,such as in transmission poles,a high uniform prestress would result ultimate strength and in brittle failure.In such a case,partial prestressing provides the only satifactory solution.The advantages of partial prestressing are important.A smaller prestress force will be required,permitting reduction in the number of tendons and anchorages.The necessary flexural strength may be provided in such cases either by a combination of prestressed tendons and non-prestressed reinforcing bars,or by an adequate number of high-tensile tendons prestredded to level lower than the prestressing force isless,the size of the bottom flange,which is requied mainly to resist the compression when a beam is in the unloaded stage,can be reduced or eliminated altogether.This leads in turn to significant simplification and cost reduction in the construction of forms,as well as resulting in structures that are mor pleasing esthetically.Furthermore,by relaxing the requirement for low service load tension in the concrete,a significant improvement can be made in the deflection characteristics of a beam.Troublesome upward camber of the member in the unloaded stage fan be avoeded,and the prestress force selected primarily to produce the desired deflection for a particular loading condition.The behavior of partially prestressed beamsm,should they be overloaded to failure,is apt to be superior to that of fully prestressed beams,because the improved ductility provides ample warning of distress.英译汉:荷载作用在结构上的荷载通常分为恒载或活载。
土木工程毕业设计中英文翻译.doc
附录：中英文翻译英文部分：LOADSLoads that act on structures are usually classified as dead loads or live loads.Dead loads are fixed in location and constant in magnitude throughout the life of the ually the self-weight of a structure is the most important part of the structure and the unit weight of the material.Concrete density varies from about 90 to 120 pcf (14 to 19 2KN/m)for lightweight concrete,and is about 145 pcf (23 2KN/m)for normal concrete.In calculating the dead load of structural concrete,usually a 5 pcf (1 2KN/m)increment is included with the weight of the concrete to account for the presence of the reinforcement.Live loads are loads such as occupancy,snow,wind,or traffic loads,or seismic forces.They may be either fully or partially in place,or not present at all.They may also change in location.Althought it is the responsibility of the engineer to calculate dead loads,live loads are usually specified by local,regional,or national codes and specifications.Typical sources are the publications of the American National Standards Institute,the American Association of State Highway and Transportation Officials and,for wind loads,the recommendations of the ASCE Task Committee on Wind Forces.Specified live the loads usually include some allowance for overload,and may include measures such as posting of maximum loads will not be exceeded.It is oftern important to distinguish between the specified load,and what is termed the characteristic load,that is,the load that actually is in effect under normal conditions of service,which may be significantly less.In estimating the long-term deflection of a structure,for example,it is the characteristic load that is important,not the specified load.The sum of the calculated dead load and the specified live load is called the service load,because this is the maximum load which may reasonably be expected to act during the service resisting is a multiple of the service load.StrengthThe strength of a structure depends on the strength of the materials from which it is made.Minimum material strengths are specified in certain standardized ways.The properties of concrete and its components,the methods of mixing,placing,and curing to obtain the required quality,and the methods for testing,are specified by the American Concrete Insititue(ACI).Included by refrence in the same documentare standards of the American Society for Testing Materials(ASTM)pertaining to reinforcing and prestressing steels and concrete.Strength also depends on the care with which the structure is built.Member sizes may differ from specified dimensions,reinforcement may be out of position,or poor placement of concrete may result in voids.An important part of the job of the ergineer is to provide proper supervision of construction.Slighting of this responsibility has had disastrous consequences in more than one instance.Structural SafetySafety requires that the strength of a structure be adequate for all loads that may conceivably act on it.If strength could be predicted accurately and if loads were known with equal certainty,then safely could be assured by providing strength just barely in excess of the requirements of the loads.But there are many sources of uncertainty in the estimation of loads as well as in analysis,design,and construction.These uncertainties require a safety margin.In recent years engineers have come to realize that the matter of structural safety is probabilistic in nature,and the safety provisions of many current specifications reflect this view.Separate consideration is given to loads and strength.Load factors,larger than unity,are applied to the calculated dead loads and estimated or specified service live loads,to obtain factorde loads that the member must just be capable of sustaining at incipient failure.Load factors pertaining to different types of loads vary,depending on the degree of uncertainty associated with loads of various types,and with the likelihood of simultaneous occurrence of different loads.Early in the development of prestressed concrete,the goal of prestressing was the complete elimination of concrete ternsile stress at service loads.The concept was that of an entirely new,homogeneous material that woukd remain uncracked and respond elastically up to the maximum anticipated loading.This kind of design,where the limiting tensile stressing,while an alternative approach,in which a certain amount of tensile amount of tensile stress is permitted in the concrete at full service load,is called partial prestressing.There are cases in which it is necessary to avoid all risk of cracking and in which full prestressing is required.Such cases include tanks or reservious where leaks must be avoided,submerged structures or those subject to a highly corrosive envionment where maximum protection of reinforcement must be insured,and structures subject to high frequency repetition of load where faatigue of the reinforcement may be a consideration.However,there are many cses where substantially improved performance,reduced cost,or both may be obtained through the use of a lesser amount of prestress.Full predtressed beams may exhibit an undesirable amount of upward camber because of the eccentric prestressing force,a displacement that is only partially counteracted by the gravity loads producing downward deflection.This tendency is aggrabated by creep in the concrete,which magnigies the upward displacement due to the prestress force,but has little influence on the should heavily prestressed members be overloaded and fail,they may do so in a brittle way,rather than gradually as do beams with a smaller amount of prestress.This is important from the point of view of safety,because suddenfailure without warning is dangeroud,and gives no opportunity for corrective measures to be taken.Furthermore,experience indicates that in many cases improved economy results from the use of a combination of unstressed bar steel and high strength prestressed steel tendons.While tensile stress and possible cracking may be allowed at full service load,it is also recognized that such full service load may be infrequently applied.The typical,or characteristic,load acting is likely to be the dead load plus a small fraction of the specified live load.Thus a partially predtressed beam may not be subject to tensile stress under the usual conditions of loading.Cracks may from occasionally,when the maximum load is applied,but these will close completely when that load is removed.They may be no more objectionable in prestressed structures than in ordinary reinforced.They may be no more objectionable in prestressed structures than in ordinary reinforced concrete,in which flexural cracks always form.They may be considered a small price for the improvements in performance and economy that are obtained.It has been observed that reinforced concrete is but a special case of prestressed concrete in which the prestressing force is zero.The behavior of reinforced and prestressed concrete beams,as the failure load is approached,is essentially the same.The Joint European Committee on Concrete establishes threee classes of prestressed beams.Class 1:Fully prestressed,in which no tensile stress is allowed in the concrete at service load.Class 2:Partially prestressed, in which occasional temporary cracking is permitted under infrequent high loads.Class 3:Partially prestressed,in which there may be permanent cracks provided that their width is suitably limited.The choise of a suitable amount of prestress is governed by a variety of factors.These include thenature of the loading (for exmaple,highway or railroad bridged,storage,ect.),the ratio of live to dead load,the frequency of occurrence of loading may be reversed,such as in transmission poles,a high uniform prestress would result ultimate strength and in brittle failure.In such a case,partial prestressing provides the only satifactory solution.The advantages of partial prestressing are important.A smaller prestress force will be required,permitting reduction in the number of tendons and anchorages.The necessary flexural strength may be provided in such cases either by a combination of prestressed tendons and non-prestressed reinforcing bars,or by an adequate number of high-tensile tendons prestredded to level lower than the prestressing force is less,the size of the bottom flange,which is requied mainly to resist the compression when a beam is in the unloaded stage,can be reduced or eliminated altogether.This leads in turn to significant simplification and cost reduction in the construction of forms,as well as resulting in structures that are mor pleasing esthetically.Furthermore,by relaxing the requirement for low service load tension in the concrete,a significant improvement can be made in the deflection characteristics of a beam.Troublesome upward camber of the member in the unloaded stage fan be avoeded,and the prestress force selected primarily to produce the desired deflection for a particular loading condition.The behavior of partially prestressed beamsm,should they be overloaded to failure,is apt to be superior to that of fully prestressed beams,because the improved ductility provides ample warning of distress.英译汉：荷 载作用在结构上的荷载通常分为恒载或活载。
土木工程毕业外文翻译
1.Central iron & Steel Research institute, Beijing 100081, China2.Chinese Society for Metals, Beijing 100711, China高层建筑与钢结构HUi Wei-jun,DONG HanWENG Yu-ging,CHEN Si-lian,WANG Mao-giu摘要耐火钢其实就是对火灾有一定抵抗能力的钢材，日本认为耐火钢是焊接结构用轧制钢材的一类，在我国它是建筑用低合金钢的一种。
耐火钢于普通的建筑用钢不同，它要求具有良好的耐高温性能，作为常温下的承载材料，只要求在遇到火灾的较短时间内（1到3小时）高温条件下能够保持高的屈服强度，常温下钢材强度的2/3相当于该材料的长期允许应力值，当发生火灾时，如果耐火钢的屈服点仍然在此值以上，建筑物就不会倒塌。
因此，就要求耐火钢在一定高温下的屈服不低于室温下屈服强度的2/3。
本文研究的目的在于研究提高耐火港的强韧性、抗震性和耐火性能。
关键字高层建筑；钢结构；发展应用1.前言近年来，虽然一般的建筑结构设计取得了很大的进步，但是取得显著成绩的还要数超高层建筑结构设计。
最初的高层建筑设计是从钢结构的设计开始的。
钢筋混凝土和受力外包钢筒系统运用起来是比较经济的系统，被有效地运用于大批的民用建筑和商业建筑中。
50层到100层的建筑被成为超高层建筑。
而这种建筑在美国被广泛的应用是由于新的结构系统的发展和创新。
这样的高度需要大柱和梁的尺寸，这样以来可以使建筑物更加坚固以至于在允许的限度范围内承受风荷载而不产生弯曲和倾斜。
过分的倾斜会导致建筑物的隔离构件、顶棚以及其它建筑细部产生循环破坏。
除此之外，过大的摇动也会使建筑物的使用者感觉到这样的晃动而产生不舒服的感觉。
无论是钢筋混凝土结构系统还是钢结构系统都充分利用了整个建筑的刚度潜力，因此，不能指望利用多余的刚度来限制侧向位移。
土木工程毕业设计--外文翻译
1 Introduction and scope1.1 Aims of the ManualThis Manual provides guidance on the design of reinforced and prestressed concrete building structures. Structures designed in accordance with this Manual will normally comply with DD ENV 1992-1-1: 19921 (hereinafter referred to as EC2).1.2 Eurocode systemThe structural Eurocodes were initiated by the European Commission but are now produced by the Comité Européen de Normalisation (CEN) which is the European standards organization, its members being the national standards bodies of the EU and EFTA countries,e.g. BSI.CEN will eventually publish these design standards as full European Standards EN (Euronorms), but initially they are being issued as Prestandards ENV. Normally an ENV has a life of about 3 years to permit familiarization and trial use of the standard by member states. After formal voting by the member bodies, ENVs are converted into ENs taking into account the national comments on the ENV document. At present the following Eurocode parts have been published as ENVs but as yet none has been converted to an EN:DD ENV 1991-1-1: Basis of design and actions on structures (EC1)DD ENV 1992-1-1: Design of concrete structures (EC2)DD ENV 1993-1-1: Design of steel structures (EC3)DD ENV 1994-1-1: Design of composite steel and concrete structures (EC4)DD ENV 1995-1-1: Design of timber structures (EC5)DD ENV 1996-1-1: Design of masonry structures (EC6)DD ENV 1997-1-1: Geotechnical design (EC7)DD ENV 1998-1-1: Earthquake resistant design of structures (EC8)DD ENV 1999-1-1: Design of aluminium alloy structures (EC9)Each Eurocode is published in a number of parts, usually with ‘General rules’ and ‘Rules for buildings’ in Part 1. The various parts of EC2 are:Part 1.1 General rules and rules for buildings;Part 1.2 Supplementary rules for structural fire design;Part 1.3 Supplementary rules for precast concrete elements and structures;Part 1.4 Supplementary rules for the use of lightweight aggregate concrete;Part 1.5 Supplementary rules for the use of unbonded and external prestressing tendons;Part 1.6 Supplementary rules for plain or lightly reinforced concrete structures;Part 2.0 Reinforced and prestressed concrete bridges;Part 3.0 Concrete foundations;Part 4.0 Liquid retaining and containment structures.All Eurocodes follow a common editorial style. The codes contain ‘Principles’ and‘Application rules’. Principles are general statements, definitions, requirements and sometimes analytical models. All designs must comply with the Principles, and no alternative is permitted. Application rules are rules commonly adopted in design. They follow the Principles and satisfy their requirements. Alternative rules may be used provided that compliance with the Principles can be demonstrated.Some parameters in Eurocodes are designated by | _ | , commonly referred to as boxed values. The boxed values in the Codes are indicative guidance values. Each member state is required to fix the boxed value applicable within its jurisdiction. Such information would be found in the National Application Document (NAD) which is published as part of each ENV.There are also other purposes for NADs. NAD is meant to provide operational information to enable the ENV to be used. For certain aspects of the design, the ENV may refer to national standards or to CEN standard in preparation or ISO standards. The NAD is meant to provide appropriate guidance including modifications required to maintain compatibility between the documents. Very occasionally the NAD might rewrite particular clauses of the code in the interest of safety or economy. This is however rare.1.3 Scope of the ManualThe range of structures and structural elements covered by the Manual is limited to building structures that do not rely on bending in columns for their resistance to horizontal forces and are also non-sway. This will be found to cover the vast majority of all reinforced and prestressed concrete building structures. In using the Manual the following should be noted:• The Manual has been drafted to comply with ENV 1992-1-1 together with the UK NAD• Although British Standards have been referenced as loading codes in Sections 3 and 6,to comply with the UK NAD, the Manual can be used in conjunction with other loading codes • The structures are braced and non-sway• The concrete is of normal weight• The structure is predominantly in situ• Prestressed concrete members have bonded or unbonded internal tendons• The Manual can be used in conjunction with all commonly used materials in construction; however the data given are limited to the following:– concrete up to characteristic cylinder strength of 50N/mm2 (cube strength 602N/mm)– high-tensile reinforcement with characteristic strength of 4602N/mm– mild-steel reinforcement with characteristic strength of 2502N/mm– prestressing tendons with 7-wire low-relaxation (Class 2) strands• High ductility (Class H) has been assumed for:– all ribbed bars and grade 250 bars, and– ribbed wire welded fabric in wire sizes of 6mm or over• Normal ductility (Class N) has been assumed for plain or indented wire welded fabric.For structures or elements outside this scope EC2 should be used.1.4 Contents of the ManualThe Manual covers the following design stages:• gene ral principles that govern the design of the layout of the structure• initial sizing of members• estimating of quantities of reinforcement and prestressing tendons• final design of members.2 General principlesThis section outlines the general principles that apply to both initial and final design of both reinforced and prestressed concrete building structures, and states the design parameters that govern all design stages.2.1 GeneralOne engineer should be responsible for the overall design, including stability, and should ensure the compatibility of the design and details of parts and components even where some or all of the design and details of those parts and components are not made by the same engineer.The structure should be so arranged that it can transmit dead, wind and imposed loads in a direct manner to the foundations. The general arrangement should ensure a robust and stable structure that will not collapse progressively under the effects of misuse or accidental damage to any one element.The engineer should consider engineer site constraints, buildability2, maintainability and decommissioning.The engineer should take account of his responsibilities as a ‘Designer’ under the Construction (Design & Management) Regulations.32.2 StabilityLateral stability in two orthogonal directions should be provided by a system of strongpoints within the structure so as to produce a braced non-sway structure, in which the columns will not be subject to significant sway moments. Strongpoints can generally be provided by the core walls enclosing the stairs, lifts and service ducts. Additional stiffness can be provided by shear walls formed from a gable end or from some other external or internal subdividing wall. The core and shear walls should preferably be distributed throughout the structure and so arranged that their combined shear centre is located approximately on the line of the resultant in plan of the applied overturning forces. Where this is not possible, the resulting twisting moments must be considered when calculating the load carried by each strongpoint. These walls should generally be of reinforced concrete not less than 180mm thick to facilitate concreting, but they may be of 215mm brickwork or 190mm solid blockwork properly tied and pinned up to the framing for low- to medium-rise buildings.Strongpoints should be effective throughout the full height of the building. If it is essential for strongpoints to be discontinuous at one level, provision must be made to transfer the forces toother vertical components.It is essential that floors be designed to act as horizontal diaphragms, particularly if precast units are used.Where a structure is divided by expansion joints each part should be structurally independent and designed to be stable and robust without relying on the stability of adjacent sections.2.3 RobustnessAll members of the structure should be effectively tied together in the longitudinal, transverse and vertical directions.A well-designed and well-detailed cast-in situ structure will normally satisfy the detailed tying requirements set out in subsection 5.11.Elements whose failure would cause collapse of more than a limited part of the structure adjacent to them should be avoided. Where this is not possible, alternative load paths should be identified or the element in question strengthened.2.4 Movement jointsMovement joints may need to be provided to minimize the effects of movements caused by, for example, shrinkage, temperature variations, creep and settlement.The effectiveness of movement joints depends on their location. Movement joints should divide the structure into a number of individual sections, and should pass through the whole structure above ground level in one plane. The structure should be framed on both sides of the joint. Some examples of positioning movement joints in plan are given in Fig. 2.1.Movement joints may also be required where there is a significant change in the type of foundation or the height of the structure. For reinforced concrete frame structures in UK conditions, movement joints at least 25mm wide should normally be provided at approximately 50m centres both longitudinally and transversely. In the top storey and for open buildings and exposed slabs additional joints should normally be provided to give approximately 25m spacing. Joint spacing in exposed parapets should be approximately 12m.Joints should be incorporated in the finishes and in the cladding at the movement joint locations.2.5 Fire resistance and durabilityFor the required period of fire resistance (prescribed in the Building Regulations), the structure should:• have adequate loadbearing capacity• limit the temperature rise on the far face by sufficient insulation, and• have sufficient integrity to prevent the formation of crack s that will allow the passage of fire and gases.Fig. 2.1 Location of movement jointsThe design should take into account the likely deterioration of the structure and its components in their environment having due regard to the anticipated level of maintenance. The following inter-related factors should be considered:• the required performance criteria• the expected environmental conditions• the composition, properties and performance of materials• the shape of members and detailing• the quality of workmanship• any protective measure• the likely maintenance during the intended life.Concrete of appropriate quality with adequate cover to the reinforcement should be specified. The above requirements for durability and fire resistance may dictate sizes for members greater than those required for structural strength alone.3 Design principles – reinforced concrete3.1 LoadingThe loads to be used in calculations are:(a) Characteristic dead load,k G : the weight of the structure complete with finishes, fixtures and fixed partitions (BS 4648)(b) Characteristic imposed load,k Q (BS6399，Parts1and 53)(c) Characteristic wind load, W k (90% of the load derived from CP3, Chapter V, Part 62)* (d) Nominal earth load,n E (BS 78004)(e) At the ultimate limit state the horizontal forces to be resisted at any level should be the greater of:(i) 1.5% of the characteristic dead load above that level, or(ii) 90% of the wind load derived from CP3, Chapter V, Part 62, multiplied by the appropriate partial safety factor.The horizontal forces should be distributed between the strongpoints according to their stiffness.In using the above documents the following modifications should be noted:(f) The imposed floor loads of a building should be treated as one load to which the reduction factors given in BS 6399: Part 1:51996are applicable.(g) Snow drift loads obtained from BS 6399: Part 3:51998 should be multiplied by 0.7 and treated in a similar way to an imposed load and not as an accidental load.3.2 Limit statesThis Manual adopts the limit-state principle and the partial factor format of EC2.3.2.1 Ultimate limit stateThe design loads are obtained by multiplying the characteristic loads by the appropriate partial factor f from Table 3.1.The ‘adverse’ and ‘beneficial’ factors should be used so as to produce the most onerous condition.3.2.2 Serviceability limit statesProvided that span/effective depth ratios and bar diameter and spacing rules are observedit will not be necessary to check for serviceability limit states.fThe Table uses the simplified combination permitted in EC2.†For pressures arising from an accidental head of water at ground level a partial factor of 1.15 may be used.3.3 Material and design stressesDesign stresses are given in the appropriate sections of the Manual. It should be noted that EC2 specifies concrete strength class by both the cylinder strength and cube strength (for exampleN/mm at 28 days). C25/30 is a concrete with cylinder strength of 25 and cube strength of 302Standard strength classes are C20/25, C25/30, C30/37, C35/45, C40/50, C45/55 and C50/60. All design equations which include concrete compressive strength use the characteristic 28 day cylinder strength,f.ckPartial factors for concrete are 1.5 for ultimate limit state and 1.0 for serviceability limit state. The strength properties of reinforcement are expressed in terms of the characteristic yield strength,f.ykPartial factors for reinforcement steel are 1.15 for ultimate limit state and 1.0 for serviceability limit state.4 Initial design – reinforced concrete4.1 IntroductionIn the initial stages of the design of building structures it is necessary, often at short notice,to produce alternative schemes that can be assessed for architectural and functional suitability and which can be compared for cost. They will usually be based on vague and limited information on matters affecting the structure such as imposed loads and nature of finishes, let alone firm dimensions, but it is nevertheless expected that viable schemes be produced on which reliable cost estimates can be based.It follows that initial design methods should be simple, quick, conservative and reliable. Lengthy analytical methods should be avoided.This section offers some advice on the general principles to be applied when preparing a scheme for a structure, followed by methods for sizing members of superstructures. Foundation design is best deferred to later stages when site investigation results can be evaluated.The aim should be to establish a structural scheme that is suitable for its purpose, sensibly economical, and not unduly sensitive to the various changes that are likely to be imposed as the overall design develops.Sizing of structural members should be based on the longest spans (slabs and beams) and largest areas of roof and/or floors carried (beams, columns, walls and foundations). The same sizes should be assumed for similar but less onerous cases – this saves design and costing time at this stage and is of actual benefit in producing visual and constructional repetition and hence, ultimately, cost benefits.Simple structural schemes are quick to design and easy to build. They may be complicated later by other members of the design team trying to achieve their optimum conditions, but a simple scheme provides a good ‘benchmark’ at the initial stage.Loads should be carried to the foundation by the shortest and most direct routes. In constructional terms, simplicity implies (among other matters) repetition; avoidance of congested, awkward or structurally sensitive details and straightforward temporary works with minimal requirements for unorthodox sequencing to achieve the intended behaviour of the completed structure.Standardized construction items will usually be cheaper and more readily available than purpose-made items.4.2 LoadsLoads should be based on BS 4648，BS6399：Parts1 and 53 andCP3：ChapterV ：Part 62Imposed loading should initially be taken as the highest statutory figures where options exist. The imposed load reduction allowed in the loading code should not be taken advantage of in the initial design stage except when assessing the load on the foundations.Loading should be generous and not less than the following in the initial stages:floor finish (screed) 1.82kN/mmceiling and service load 0.52kN/mmAllowance for:demountable lightweight partitions* 1.02kN/mmblockwork partitions† 2.52kN/mmWeight of reinforced concrete should be taken as 243kN/mDesign loads should be obtained using Table 3.1.4.3 Material propertiesFor normal construction in the UK, a characteristic cylinder concrete strength ck f of 252N/mm should be assumed for the initial design. In areas with poor aggregates this may have to be reduced.For UK steels a characteristic strength yk f of 4602N/mm should be used for high-tensile reinforcement and 2502N/mm for mild steel.4.4 Structural form and framingThe following measures should be adopted:(a) provide stability against lateral forces and ensure braced construction by arranging suitable shear walls deployed symmetrically wherever possible(b) adopt a simple arrangement of slabs, beams and columns so that loads are carried to the foundations by the shortest and most direct routes(c) allow for movement joints (see subsection 2.4)(d) choose an arrangement that will limit the span of slabs to 5m to 6m and beam spans to 8m to l0m on a regular grid; for flat slabs restrict column spacings to 8m(e) adopt a minimum column size of 300mm × 300mm or equivalent area(f) provide a robust structure.The arrangement should take account of possible large openings for services and problems with foundations, e.g. columns immediately adjacent to site boundaries may require balanced or other special foundations.4.5 Fire resistance and durabilityThe size of structural members may be governed by the requirement of fire resistance and may also be affected by the cover necessary to ensure durability. Table 4.1 shows the minimum practical member sizes for different periods of fire resistance and the cover to the main reinforcement required for continuous members in dry and humid environments without frost. For other exposure classes, cover should be increased. For simply supported members, sizes and cover should be increased (see Section 5 and Appendix C).4.6 StiffnessTo provide adequate stiffness, the effective depths of beams, slabs and the waist of stairs should not be less than those derived from Table 4.2.Beams should be of sufficient depth to avoid the necessity for excessive compression reinforcement and to ensure that economical amounts of tension and shear reinforcement are provided. This will also facilitate the placing of concrete.*To be treated as imposed loads.†To be treated as dead load s when the layout is fixed.Table 4.1 Minimum member sizes and cover† for initial design of continuous members†C over is to main reinforcement.Table 4.2 Basic ratios of span/effective depth for initial design (yk f = 4602N/mm )1. For two-way spanning slabs (supported on beams), the check on the ratio of span/effective depth should be carried out on the shorter span. For flat slabs, the longer span should be taken.2. For flanged sections with the ratio of the flange to the rib width greater than 3, the Table value should be multiplied by 0.8.3. For members, other than flat slab panels, which support partitions liable to be damaged by excessive deflection of the member, and where the span exceeds 7m, the Table value should be multiplied by 7/span.4. For flat slabs where the greater span exceeds 8.5m, the Table value should be multiplied by 8.5/span.第一章引言和适用范围1.1手册的作用这本手册为设计钢筋和预应力混凝土建筑结构提供了指导。
土木工程专业毕业设计外文翻译
High-Rise BuildingsIn troducti onIt is difficult to defi ne a high-rise buildi ng . One may say that a low-rise build ing ranges from 1 to 2 stories . A medium-rise buildi ng p robably ran ges betwee n 3 or 4 stories up to 10or 20 stories or more .Although the basic principles of vertical and horiz on tal subsystem desig n rema in the samefor low- , medium- , or high-rise build ings , whe n a build ing gets high the verticalsubsystemsbecome a con trolli ng p roblem for two reas ons . Higher vertical loads will requirelarger colu mns , walls , and shafts . But , more sig nifica ntly , the overtur ning mome nt and theshear deflect ions p roduced by lateral forces are much larger and must be carefully pro vided for .The vertical subsystems in a high-rise buildi ng tran smit accumulated gravity load from storyto story , thus requiri ng larger colu mn or wall secti ons to support such loadi ng .In additi onthese same vertical subsystems must tran smit lateral loads , such as wi nd or seismic loads , tothe foun datio ns. However , in con trast to vertical load , lateral load effects on build ings arenot lin ear and in crease rap idly with in crease in height . For example under wind load , theoverturning moment at the base of buildings varies approximately as the square of a buildings mayvary as the fourth power of buildings height , other things being equal. Earthquake produces an evenmore pronoun ced effect.When the structure for a low-or medium-rise building is designed for dead and live load , it isalmost an in here nt property that the colu mns , walls , and stair or elevator shafts can carrymost of the horiz on tal forces . The p roblem is p rimarily one of shear resista nee . Moderateadditi on braci ng for rigid frames in easily be pro vided by filli ng certa in pan els ( or eve n“short ” buildi all pan els ) without in creas ing the sizes of the colu mns and girders otherwise required forvertical loads.Unfortunately , this is not is for high-rise buildings because the problem is p rimarily resistanee to mome nt and deflect ion rather tha n shear alone . Sp ecial structural arra ngeme nts will often have to be made and additi onal structural material is always required for the columns , girders ,walls , and slabs in order to made a high-rise buildi ngs sufficie ntly resista nt to much higherlateral deformati ons .As p reviously men ti oned , the qua ntity of structural material required per square foot offloor of a high-rise buildings is in excess of that required for low-rise buildings . The verticalcomponents carrying the gravity load , such as walls , columns , and shafts , will need to bestrengthened over the full height of the build ings . But qua ntity of material required for resisting lateral forces is eve n more sig nifica nt .With rei nforced con crete , the qua ntity of material also in creases as the nu mber ofstories in creases . But here it should be no ted that the in crease in the weight of material addedfor gravity load is much more sizable tha n steel , whereas for windIn crease the effective width of the mome nt-resisti ng subsystems . This is very usefulbecause in creas ing the width will cut dow n the overtur n force directly and willreduce deflecti on by the third po wer of the width in crease , other things rema iningcin sta nt . However , this does require that vertical components of the widenedsubsystem be suitably connected to actually gain this ben efit.Desig n subsystemssuch that the components are made to in teract in the most efficientmanner . For example , use truss systems with chords and diagonals efficiently stressed ,place reinforcing for walls at critical locati ons , and op timize stiff ness ratios for rigid frames .In crease the material in the most effective resist ing components . For exa mple ,materials added in the lower floors to the flan ges of colu mns and conn ect ing girderswill directly decrease the overall deflect ion and in crease the mome nt resista neewithout con tribut ing mass in the upper floors where the earthquake p roblem isaggravated .Arrange to have the greater part of vertical loads be carried directly on the primarymoment-resisting components . This will help stabilize the build ings aga inst ten sileovertu rning forces by p reco mp ress in gthe major overturn-resisti ng components .The local shear in each story can be best resisted by strategic pl aceme nt if solid wallsor the use of diagonal members in a vertical subsystem . Resist ing these shears solelyby vertical members in bending is usually less econo mical , since achiev ing sufficient bending resista nee in the colu mns and conn ect ing girders will require morematerial and con struct ion en ergy tha n using walls or diago nal members .Sufficie nt horiz on tal dia phragm acti on should be pro vided floor . This will help tobring the various resist ing eleme nts to work together in stead of sep arately .Create mega-frames by joining large vertical and horizontal components such as two or moreelevator shafts at multistory intervals with a heavy floor subsystems , or by use of verydee p girder trusses .Remember that all high-rise build ings are esse ntially vertical can tilevers which aresupported at the ground . When the above principles are judiciously applied , structurally desirable schemes can be obta ined by walls , cores , rigid frames, tubular con struct ion , and othervertical subsystems to achieve horiz on tal stre ngth and rigidity . Some of these app licati ons will now be described in subseque nt secti ons in the followi ng .Shear-Wall SystemsWhen shear walls are comp atible with other fun cti onal requireme nts , they can beeconomically utilized to resist lateral forces in high-rise buildings . For example , ap artme nt build ings n aturally require many sep arati on walls . Whe n some of these are desig ned to be load the in crease for lateral force resista nee is not that much more since the weight of a concrete buildings helps to resist overturn . On the other hand , the problem of desig n for earthquake forces . Additi onal mass in the upper floors will give rise to a greater overall lateral force un der the of seismic effects .In the case of either concrete or steel design , there are certain basic principles for pro vid ing additi onal resista nee to lateral to lateral forces and deflecti ons in high-rise build ings without too much sacrifire in economy .1.2. 3. 4. 5. 6. 7.solid , they can act as shear walls to resist lateral forces and to carry the vertical load aswell . For buildi ngs up to some 20storise , the use of shear walls is com mon .If give n sufficie nt len gth ,such walls can econo mically resist lateral forces up to 30 to 40 stories or more .However , shear walls can resist lateral load only the plane of the walls ( i.e .not in adireti on perpen dicular to them ) . There fore ,it is always n ecessary to pro vide shear walls in two perpen dicular directi ons can be at least in sufficie nt orie ntati on so that lateral force in any direct ion can be resisted .In additi on , that wall layout should reflect con siderati on of any torsi onal effect .In desig n p rogress , two or more shear walls can be conn ected to from L-sha ped or cha nnel-sha ped subsystems .In deed ‘internal shear walls can be conn ected to from a rectangular shaft that will resist lateral forces very efficiently . If all external shear walls are continuously connected , then the whole buildings acts as tube , and conn ected , the n the whole buildi ngs acts as a tube , and is excelle nt Shear-Wall Seystems resist ing lateral loads and torsi on .Whereas con crete shear walls are gen erally of solid type with openings whe n necessary, steel shear walls are usually made of trusses . These trusses can have single diagonals , “X” diagona|sor “ K” arrang e nhs . A trussed wall will have its members act esse ntially in direct tension or comp ressi on un der the acti on of view , and they offer some opportunity anddeflection-limitation point of view , and they offer some opportunity for penetration between members . Of course , the inclined members of trusses must be suitable p laced so as not to in terfere with requireme nts for wion dows and for circulati on service pen etrati ons though these walls .As stated above , the walls of elevator , staircase ,and utility shafts form n atural tubes and are com monly empio yed to resist both vertical and lateral forces . Since these shafts are no rmally recta ngular or circular in cross-sect ion , they can offer an efficie nt means for resist ing mome nts and shear in all directi ons due to tube structural action . But a p roblem in the desig n of these shafts is pro vided sufficie nt stre ngth around door openings and other pen etrati ons through these eleme nts . For rein forced concrete construction , special steel reinforcements are placed around such opening .In steel con struct ion , heavier and more rigid conn ecti ons are required to resist rack ing at the openings .In many high-rise build ings , a comb in ati on of walls and shafts can offer excelle ntresista nee to lateral forces whe n they are suitably located ant conn ected to one ano ther . It is also desirable that the stiff ness offered these subsystems be more-or-less symmertrical in all direct ions .Rigid-Frame SystemsIn the desig n of architectural build ings , rigid-frame systems for resist ing vertical and lateral loads have long bee n acce pted as an imp orta nt and sta ndard means for designingbuilding . They are empioyed for low-and medium means for designing build ings . They are empio yed for low- and medium up to high-rise build ing p erha ps 70 or 100 stories high . Whe n comp ared to shear-wall systems , these rigid frames both with in and at the outside of a buildi ngs . They also make use of the stiff ness in beams and colu mns that are required for the build ings in any case , but the colu mns are made stron ger whe n rigidly conn ected to resist the lateral as well as vertical forces though frame bending .Freque ntly , rigid frames will not be as stiff as shear-wall con struct ion , and therefore may p roduce excessive deflecti ons for the more sle nder high-rise buildi ngs desig ns . But because of this flexibility , they are ofte n con sidered as being more ductile and thus less susceptible to catastr op hic earthquake failure whe n comp ared with ( some ) shear-wall desig ns . For exa mple , if over stress ing occurs at certa in p orti ons of a steel rigid frame ( i.e., near the joi nt ) , ductility will allow the structure as a whole to deflect a little more , but it will by no means colla pse eve n un der a much larger force tha n exp ected on the structure . For this reas on , rigid-frame con struct ion is considered by some to be a “ best ” seisresisting type for high-rise steel buildings . On the other hand ,it is also unlikely that a well-designed share-wall system would colla pse.In the case of con crete rigid frames ,there is a diverge nee of opinion .It true that if a con crete rigid frame is desig ned in the conven ti onal manner , without sp ecial care to produce higher ductility , it will not be able to withstand a catastrophic earthquake that can p roduce forces several times lerger tha n the code desig n earthquake forces . therefore , some believe that it may not have additi onal cap acity p ossessed by steel rigid frames . But moder n research and exp erie nee has in dicated that con crete frames can be desig ned to be ductile , whe n sufficie nt stirr ups and joinery rein forceme nt are designed in to the frame . Modern buildings codes have specifications for the so-called ductile con crete frames . However , at p rese nt , these codesofte n require excessive rein forceme nt at certa in points in the frame so as to cause con gesti on and result in construction difficulties 。
土木工程毕业设计外文翻译
Ecological Engineering 35(2009)1043–1050Contents lists available at ScienceDirectEcologicalEngineeringj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e c o l e ngEnhancement of nitrogen removal in towery hybrid constructed wetland to treat domestic wastewater for small rural communitiesa r t i c l e i n f o Article history:Received 11September 2008Received in revised form 6January 2009Accepted 23March 2009Keywords:Constructed wetlands Nitrification DenitrificationDomestic wastewater Nitrogen removal Nitrifying bacteria Denitrifying bacteriaa b s t r a c tEfforts to protect watercourses,especially sources of drinking water,particularly in rural areas,are now underway in China.Nitrogen present in wastewater,due to its role in eutrophication and potential toxicity to aquatic species,is a focus of primary concern.Constructed wetlands (CWs),a simpler,less costly treat-ment alternative,have been used to treat domestic wastewater for small communities.Although showing great promise for removing carbonaceous materials from wastewater,wetland systems have not been suc-cessful in removing nitrogen mainly due to lack of dissolved oxygen (DO).To enhance nitrogen removal,a novel CW configuration with three stages,towery hybrid constructed wetland (THCW),was designed.The first and third stages were rectangle subsurface horizontal flow CWs,and the second stage was a cir-cular three-layer free-water flow CW.Increased DO by passive aeration of a tower type cascade overflow from the upper layer into the lower layer in the second stage of the wetland enhanced nitrification rates.Denitrification rates were also improved by additional organic matter supplied as a result of bypass influ-ent directly into the second stage.Evergreen tree Pond Cypress (Taxodium ascendens ),industrial plants Mat Rush (Schoenoplectus trigueter )and Wild Rice shoots (Zizania aquatica ),ornamental floriferous plants Pygmy Waterlily (Nymphaea tetragona )and Narrow-leaved Cattail (Typha angustifolia )were planted in the wetland.The average percentage of removal was 89%,85%,83%,83%and 64%for total suspended solid,chemical oxygen demand,ammonia nitrogen,total nitrogen and total phosphorus,respectively.There was no significant difference (p <0.05)at low and high hydraulic loads (16cm/d and 32cm/d)for perfor-mance of THCW.Nitrifying and denitrifying bacteria as well as potential nitrification activity and potential denitrification rates measured have shown that nitrification–denitrification is the main mechanism for nitrogen removal in the wetland.THCW also provided additional aesthetic benefits.©2009Elsevier B.V.All rights reserved.1.IntroductionWidespread demands for improved receiving water quality,especially drinking water are currently driving the implementa-tion of advanced wastewater treatment techniques.In rural areas of China,the domestic sewage was discharged directly into water-courses,lakes,rivers,soil or sea.This discharge of poorly treated sewage is responsible for many watercourses,reservoirs and lakes not meeting their quality objectives.Many small communities located in rural areas of China lack adequate domestic wastewa-ter treatment facilities.Wastewater collection and treatment are problematic in these areas due to mountainous terrain,dispersed population,and a lower economic base.In order for resource-scarce,economically developing rural areas to adopt wastewater treatment,the treatment technologies must be cost-effectiveand easy to adopt,require less energy input and maintenance costs,and be capable of meeting effluent discharge standards.The centralized wastewater treatment plants based on activated sludge or bacterial beds processes which are utilized in large and small cities are not economically adaptable for such rural areas,mainly due to the construction costs of sewage collec-tors.On the other hand,the nitrogen content of many watercourses,reservoirs and lakes in China does not meet the standards of national and local governments.It now seems clear that in many lakes,most estuaries,and almost all coastal waters,nitrogen also plays a major role in eutrophication.Therefore,national regula-tions have recently been issued;the project is called “new country construction”.The regulations stipulate that the domestic wastew-ater in rural areas must be treated before being discharged into a watercourse or soil.Constructed wetlands (CWs)have been scientifically tested and constructed for on-site treatment in rural areas for small units and small villages.Simple construction,large buffering capacity,little1044 F.Ye,Y.Li/Ecological Engineering35(2009)1043–1050excess sludge production,simple operation and maintenance,as well as low operational and maintenance costs are the advantages of CWs.The treatment efficiency is generally good in terms of sus-pended solid(SS),biochemical oxygen demand(BOD)and chemical oxygen demand(COD)removal;but nitrogen removal,particularly ammonia nitrogen(NH3-N),in most of the present generation of operating wetland systems(predominately horizontalflow beds)is deficient mainly due to the insufficient amount of oxygen available to the nitrifying microbial population in CWs.Generally nitrogen removal in subsurface horizontalflow(SSHF)systems is about 30–40%,and means of30%(NH3-N)and39.6%total nitrogen(TN) are given for268European constructed wetlands.However,sin-gle sets of data concerning removal efficiency differ extremely in most of the long-term evaluated SSHF systems(Vymazal,2005). This problem is caused by an unsatisfactory hydraulic conductivity and an oxygenation deficiency in the root zone.To achieve higher elimination rates,verticalflow systems have been developed.But, again,removal of nutrients often turned out to be insufficient in all these designs of constructed wetlands.Nitrification does occur in conventional wetland systems,but typically requires long hydraulic retention time(HRT).Biological nitrification–denitrification is usually the most sig-nificant nitrogen removal mechanism in CWs;other mechanisms such as plant uptake,substrate adsorption and ammonia volatiliza-tion are generally of less importance(Green,1997).Although plant uptake of nitrogen occurs,only a minor fraction can typically be removed by plants on a sustainable basis.The uptake capacity of emergent macrophytes,if harvested,is roughly200–2500kg N/ka per year,whereas the capacity of submerged macrophytes is lower(<700kg N/ka per year)(Brix,1994).Furthermore,if the wetlands are not harvested,the vast majority of the nutri-ents that have been incorporated into the plant tissue will be returned to the water by decomposition processes.The biologi-cal nitrification–denitrification process depends on various factors such as temperature,pH,alkalinity and,above all,electron and dissolved oxygen(DO)availability.The removal of NH3-N is largely dependent on the O2supply.The bed medium is con-tinuously water-saturated and therefore generally anaerobic.The plants transport O2to the rhizosphere,thereby creating aerobic microsites,adjacent to the roots and rhizomes where NH4+will be oxidizedfirst to nitrite by nitrifying bacteria such as Nitrosomonas and then to nitrate by bacteria with the same enzymatic equip-ment as Nitrobacter.After diffusion in an anaerobic zone of the wetland and in the presence of an electron source such as lac-tate or hydrogen gas,nitrates will serve as an electron sink for a very large family of bacteria called nitrate reducers.Nitrate is finally reduced to N2and emitted into the atmosphere(Drio et al., 1997).The rate of nitrification is significantly lower than that of denitrification and,in fact,becomes the limiting factor for con-trolling nitrogen removal.When1g of NH3-N is oxidized to be NO3-N,4.3g of oxygen is required.For NH3-N with a concentra-tion of1mg/L,nitrification will not occur successfully until the DO reaches4.6mg/L.The mineralization of the excess influent BOD likely depleted the available oxygen and retarded nitrifica-tion.However,the oxygen conducted by aquaculture is limited.Root oxygen release rates from a number of submerged aquatic plants is reported to be in the range of0.5–5.2g/(m2d)(Caffreya and Kempb,1991),and from free-floating plants0.25–9.6g/(m2d)(Brix, 1997).The DO in subsurface water in vegetated subsurface bed (VSB)wetlands is normally low.For example,DO concentrations averaged less than1ppm for VSB microcosm planted systems (Steinberg and Coonrod,1994).Many studies have shown that the oxygen release from roots of different macrophytes is far less than the amount needed for aerobic degradation of organic mat-ter and nitrification.Due to low DO in VSB wetlands,nitrification is considered the rate limiting step for nitrogen removal.Nitrifi-cation can occur at low DO,but the reaction rate is considerably less than that at DO levels greater than2mg/L(Grady et al., 1980).In order to improve the nitrification rate,aeration was employed to increase the dissolved oxygen and nitrification rate.But while the removal rate of NH3-N was increased,the removal rate of NO3-N was decreased(Green,1997).Wetlands have two environ-mental characteristics that promote denitrification:one is anoxic sediments,a requisite condition for denitrification(redox poten-tial<300mV);another is a source of carbon fuel for denitrification (Vymazal,2005).About87%of the nitrogen removal by the planted wetlands was due to denitrification,with13%due to accumula-tion in sediment and plant biomass.The plants(including plant litter)and influent organic matter were each responsible for about 50%of nitrogen removal,mainly through supplying organic carbon and creating anaerobic conditions for denitrification(van Oostrom, 1995;Newman et al.,2000).Denitrification of1g NO3-N to be N2,the organic material equivalent to2.86g BOD is needed.It was found that a C:N ratio(measured as mg BOD5:mgNO x-N) of less than2.3would limit denitrification rates.However,the decomposition of organic matter takes place mainly in the forepart of CWs,which results in a lack of organic matter in the back part of CWs and low denitrification.So nitrogen removal via the nitrification–denitrification coupling may be improved if a part of CWs is sufficient in oxygen to accomplish the nitrification of NH3-N;meanwhile another part of CWs is anoxic and BOD is enough to denitrify.Small-scale constructed wetlands for rural domestic wastewater treatment are a relatively new technology,and the physical,chem-ical and biological processes which facilitate treatment are still not well understood.In hybrid systems the advantage and disadvan-tage of SSHF and free-water surface(FWS)or subsurface vertical flow(SSVF)systems can be combined to complement each other. It is possible to produce an effluent in low COD(or BOD),which is fully nitrified and partly denitrified,and hence has a much lower TN concentration.The objectives of this study were:1.To evaluate the performance of the novel CW,towery hybrid con-structed wetland(THCW),especially nitrogen removal under a high hydraulic load.The THCW was designed to increase the nitrification rate by elevating the DO level in wastewater by pas-sive oxygenation due to a cascade-type current,and improve the denitrification rate by supplying a part of the wastewater directly into the middle part of the wetland,and then couple the nitrification–denitrification.2.To assess the effects of evergreen perennial woody plants andherbage plants together in THCW on removing nitrogen,espe-cially during winter season,and plant biomass contribution to nitrogen removal processes in this wetland.3.To investigate whether the hybrid system combined with SSHFand FWS exhibits better performance in removing or transform-ing wastewater pollutants,especially nitrogen.2.Materials and methods2.1.System descriptionA THCW system designed by our research group was constructed at a village in Northern Ningbo,China.It consists of three stages dimensioned for the equivalent of40people(PE)(Fig.1).The climate is characterized by an average rainfall of1300–1400mmF.Ye,Y.Li/Ecological Engineering35(2009)1043–10501045Fig.1.Flow diagram of towery hybrid constructed wetland:1,first stage;2,second towery stage;3,third stage(discharge);4,wetland plants;5,bottom circular cell;6, middle circular cell;7,upper circular cell;8,cascade.and an air temperature annual average of16.2◦C.Extremes vary between−4.2◦C at the lowest and38.8◦C at the highest.The cold period represents about3months from December to February and during this period the effluent mean temperature was close to8◦C with5.5◦C as the lowest.Thefirst and third stages were8m long and6m wide with a depth of1.0m.The beds were constituted of three layers,the lowest layer of washed gravel(2–6cm)with a depth of20cm,the middle layer offine gravel(0.5–2.0cm)with a depth of65cm,and the upper layer of soil(0.1–0.2cm)with a depth of15cm.The bottom slope was about1%.The second stage consisted of three circular cells with diameters of7m,5m and3m, respectively,from the bottom cell to the upper cell,each0.6m deep,providing approximately38.5m2of surface area.The over-flow from the upper cell drops into the lower cell immediately creating a turbulent cascade,which increases DO and maintains oxic conditions.The bottom of the wetland was lined with a high-density polyethylene liner and the circumference of the wetland was con-structed with approximately5cm of brick to eliminate seepage and mixing of wastewater with underground water.Seedlings of Pond Cypress(Taxodium ascendens)purchased from a nurs-ery were planted0.8m apart around the circumference of the bottom of the whole wetland,and Mat Rush(Schoenoplectus trigueter)was planted in the center of the bottom of the whole wetland in a density of approximately56plants per m2in November and harvested in May of the next year.Wild Rice shoots(Zizania aquatica)were planted in a density of approx-imately9plants per m2after the Mat Rush was harvested to grow from June to October.In the second stage,the upper circular cell was planted with Pygmy Waterlily(Nymphaea tetrag-ona)in a density of approximately6plants per m2,and the middle circular cell was planted with Narrow-leaved Cattail (Typha angustifolia)in a density of approximately36plants per m2.80%of the raw wastewaterflowed continuously into thefirst stage of the wetland.20%of the raw wastewater was pumped directly into the uppermost circular cell in the second stage of the wetland,and overflowed into the middle circular cell,then over-flowed to the bottom cell.This wastewater together with water from thefirst stageflowed into the third stage of the wetland,and discharged from the end of the third stage of the wetland.Water depth was controlled with a standpipe.In Phase1,the THCW was operated with a hydraulic loading of16cm/d(corresponding to HRT of5.4d)for4months(from May2006to August2006).In Phase2, the THCW was operated with a high hydraulic loading of32cm/d (corresponding to HRT of2.7d)for8months(from September2006 to April2007).The domestic wastewater was pretreated in a septic tank(Table1).2.2.Analytical procedure2.2.1.Chemical analysisWastewater samples were collected daily(regular working days) from the inlet of thefirst stage,outlet of the second stage(only during the Phase2test)and outlet of the third stage in the THCW wetland,and formed into weekly composite samples that were pre-served and analyzed for total suspended solid(TSS),COD,NH3-N, TN,and total phosphorous(TP).Weekly in situ temperature,pH and DO measurements of each stage and cell were made using an YSI probe.TSS,COD,TN,TP and NH3-N were determined according to the Standard Methods(APHA,1998).Wild Rice shoots(Z.aquatica)and Mat Rush(S.trigueter)were harvested(by cutting all visible portions above the water surface) in October2006and May2007,respectively.The harvested plants were washed in distilled water and dried in the sun for24h and later in an oven of105◦C for another24h.The plants were weighed before and after drying for water content analysis.The dried plants were powdered and prepared for total Kjeldahl nitrogen(TKN)anal-ysis according to the Standard Methods(APHA,1998).2.2.2.Measurement of nitrification and denitrificationThe potential nitrification activity(PNA)was determined on samples in the upper5cm of sediment taken from the front part of the third stage of the wetland.The test media used con-tained per litre:0.14g K2HPO4;0.027g KH2PO4;0.59g(NH4)2SO4;1.20g NaHCO3;0.3g CaCl2·2H2O;0.2g MgSO4;0.00625g FeSO4;0.00625g EDTA;1.06g NaClO3;the pH was7.5.Sodium chlorate was used to inhibit the oxidation of nitrite to nitrate.50mL sediment slurry samples were added to100mL of test media and incubated at 25◦C on a horizontal shaker at150rpm.Subsamples were collected after2,6,20,and24h of incubation.Nitrite concentrations were measured colorimetrically.PNA was calculated by angular coeffi-cient assessment of linear regression calculated for hours and the amount of nitrite produced.Results were normalized for volume loss during sampling,referred to by dry weight(DW)and expressed as nmol of nitrite per gram dry matter per hour.Potential denitrification rate(PDR)was measured using the acetylene inhibition technique.Sediment core samples were col-lected at four locations in the back part of the third stage(two located in bulk,two located in rhizome,diameter=3.5cm),and immediately wrapped tightly in aluminium foil to prevent diffu-sion of oxygen into the sediment cores.Each of these four samples were put into a1500mL Erlenmeyerflask,and incubated in water enriched with nutrients(15mg/L NO3-N,72mg/L Ca,10mg/L Mg, 27mg/L Na,39mg/L K and2.5mg/L PO4-P).The headspace of the flasks wasflushed with N2for30min.Theflasks were shaken on a rotary shaker at60rpm.The cores were incubated for8h in dark-1046 F.Ye,Y.Li /Ecological Engineering 35(2009)1043–1050Table 1Physical and chemical characteristics of influent and effluents from THCW.a .ParameterInfluentEffluent of the second stage in Phase 2Wetland effluent Removal rate (%)Phase 1Phase 2pH7.11(0.04)7.02(0.04) 6.98(0.05) 6.86(0.04)–TSS (mg/L)124.2(20.6)28.2*(3.6)16.6*(5.2)14.2*(5.6)88.57(16.3)DO (mg/L) 1.28(0.52) 2.98*(0.38) 2.04*(0.12) 2.22*(0.13)–CODcr (mg/L)320.2(13.9)119.2*(8.8)46.7*(5.1)49.3(13.9)84.60(9.6)NH 3-N (mg/L)45.6(1.8)12.6*(0.9)8.5*(1.1)7.7*(1.3)83.11(10.2)TN (mg/L)69.38(6.66)49.06(5.12)12.4*(4.1)11.9*(3.9)82.85(8.5)TP (mg/L)6.22(0.96) 2.91*(0.85) 2.06*(0.96)2.23*(0.96)64.15(7.9)aArithmetic mean (standard error in parentheses)of 62samples (4replicates/sample)collected weekly over 1-year period.Values followed by an asterisk are significantly different from the influent (p <0.05)within the same row.ness at 20◦C.Gas samples were taken with a syringe after each hour.Headspace samples were analyzed for N 2O concentration on a gas chromatograph (Shimadzu GC-14B)equipped with an elec-tron capture detector at an operating temperature of 340◦C.PDR was expressed as mg N 2O-N per m 2sediment per hour.2.2.3.Microbial number analysisThe nitrifying and denitrifying bacteria in the sediment of the wetland were enumerated using the most probable number (MPN)calculation (Carter and Gregorich,2006)using the follow-ing media.The medium for nitrifying bacteria:13.5g Na 2HPO 4;0.7g KH 2PO 4;0.1g MgSO 4·7H 2O;0.5g NaHCO 3;2.5g (NH 4)2SO 4;14.4mg FeCl 3·6H 2O;18.4mg CaCl 2·7H 2O;1L distilled water;pH 8.0.The medium for denitrifying bacteria: 1.0g KNO 3;0.1g Na 2HPO 4;2.0g Na 2S 2O 7;0.1g NaHCO 3;0.1g MgCl 2;1L distilled water;pH 7.0.The sediments for nitrifying and denitrifying bacteria measure-ments were removed from the sediment–water interface (0–2cm)and from a deeper level (5–8cm),respectively,with the aid of a 4.7cm (inner diameter)glass tube.Slime was scraped from rocks,rooted aquatic plant materials,and were then dispersed by blend-ing into the cold water with a mixer.Aliquots (1mL)of serial 10-fold sterile distilled water dilutions of the sediment sample were trans-ferred to 96-cell microtiter plates containing each type of mediumand incubated at 28◦C for 21d (nitrifying bacteria)and 5d (denitri-fying bacteria),respectively.In order to determine the dry weight of sediment samples,10g of sediment samples were oven-dried at 105◦C overnight to produce a constant weight.The amounts of nitrifying and denitrifying bacteria in the sediment were analyzed bimonthly during the wetland operation period.2.2.4.Statistical analysisSoftware SPSS was used for all statistical analyses with one-way ANOVA test.Differences were considered as significant if p <0.05.Significance of differences within means was evaluated with the Duncan’s test.Pearson’s correlations were used for significant lin-ear relationships assessment between PDA and hydraulic load,and PDR and hydraulic load.3.ResultsThe changes in the physico-chemical parameters at influent,effluent of the second stage during Phase 2and effluent of the third stage are presented in Table 1.Water pH did not change greatly.DO was relatively higher in effluent than influent as the result of passive oxygenation of the cascade overflow in the second stage of THCW.Mean DO increased from 1.28±0.52mg/L in influent to 2.98±0.38mg/L in effluent of the second stage during Phase 2Fig.2.COD,NH 3-N,TN and TP contents on influent and discharge ports as well as removal rates from THCW during operation period.F.Ye,Y.Li/Ecological Engineering35(2009)1043–10501047Fig.3.PNA(nmol/g DW/h)and PDR(mg N2O-N/m2/h)of sediment in third stage of THCW at the end of experiment.testing.The highest removal rate that was observed was for the TSS of88.57±16.3%.Organic matter measured as COD has shown removal of84.60±9.6%.Nitrogen removal was high and averaged 83.11±10.2%and82.85±8.5%for NH3-N and TN,respectively. However,at the end of the second stage during Phase2testing, NH3-N and TN removal rates were72%and29%,respectively.It suggested that a major amount of nitrogen was transformed into NO3-N by nitrification in the second stage and54%of nitrogen was removed by denitrification and/or other mechanisms in the third stage of the wetland.Phosphorus removal of64.15±7.9%was also observed.In comparison to results of Phase2,the greater removal for all measured pollutants took place during Phase1due to the lower hydraulic loading rate employed.But there were no signifi-cant differences in removal rates for all pollutants between the two hydraulic loads(p<0.02).Fig.2describes influent and effluent concentrations,as well as removal rates of CODcr,NH3-N,TN and TP during a12-month investigation period.During both Phase1and2of the study, NH3-N and TN had been removed efficiently over the12-month experiment.The highest nitrogen removal rates were observed during thefirst10weeks and the last10weeks when the water temperature was high.However,the wetland also showed high nitrogen,organic matter and phosphorus removal efficiencies dur-ing the winter season.Additionally,mean nitrogen loss attributed to nitrification–denitrification was significantly(p<0.003)higher during the summer than in winter.Ammonia volatilization may be ruled out since the maximum pH measured in the wetland was 7.7,and it should not have been sufficient for significant ammonia gas production.Also found were no statistically significant differ-ences between all average removals at two different hydraulic loads (16cm/d and32cm/d).As shown in Fig.2,phosphorus removal did not change signif-icantly during the operation period,even at the higher hydraulic load and in the winter season.There was no significant difference in TP effluent concentrations during winter and summer operations.As seen in Fig.3,PNA and PDR increased with time over thefirst 4months.About1month later when hydraulic loading was ele-vated from16cm/d to32cm/d,PNA decreased during October to December2006and PDR decreased during October2006to Jan-uary2007.Then PNA did not change significantly till the end of the test,and PDR increased a little.PNA and PDR tallied well with MPN counts of nitrifying bacteria and denitrifying bacteria,respectively, thus showing two good positive correlations(p<0.05).As seen in Table2,the numbers of nitrifying bacteria and denitri-fying bacteria in the sediment of the wetland were all in the range of104–105MPN/g sediment.A quantitative estimation of nitrify-ing and denitrifying bacteria and their corresponding PNA and PDR (Fig.3)in the sediment of the wetland indicated higher numbers of nitrifying bacteria than denitrifying bacteria,and higher activity of PNA.To show the effects of plant harvesting on nitrogen removal,TKN content in dried weight of harvested plants in October2006and May2007was measured.It showed a much larger nitrogen mass in Mat Rush(S.trigueter)than Wild Rice shoots(Z.aquatica).Average nitrogen contents in the dried plants were6.8±0.3/kg dry plant and 4.7±0.2/kg dry plant,and the TN uptake rates of these emergent plants were17.18kg/ha per day and12.63kg/ha per day for Mat Rush(S.trigueter)and Wild Rice shoots(Z.aquatica),respectively.4.DiscussionNitrification does not remove nitrogen from wastewaters.But nitrification coupled with denitrification seems to be the major removal process in many CWs.Nitrification occurs when oxygen is present in a high enough concentration to support the growth of strictly aerobic nitrifying bacteria.Nitrification takes place in all types of CWs;however,the extent of this process is determined by oxygen availability.As NH3-N is the dominant types of nitro-gen in many wastewaters,nitrification is a limiting process for nitrogen removal from most types of CWs.Denitrification is con-sidered as a major removal mechanism for nitrogen in most types of CWs.However,the concentrations of nitrates are usually very low in wastewater and,therefore,denitrification must be coupled with nitrification.Different requirements for the presence of oxy-gen for nitrification and denitrification are the major obstacle in many treatment wetlands for achieving higher nitrogen removal.It is generally accepted that DO concentrations above1.5mg/L are essential for nitrification to occur.In this wetland,average 2.22±0.13mg/L DO in outflow during the study,which most likely resulted from the tower type cascade in the middle of THCW, indicated that DO concentrations support nitrification;this result would be consistent with much more nitrifying bacteria in the sed-iment(Table2).High DO and available organic matter,due to the bypass of influent directly into the second stage,thereby reduced competition between heterotrophs and nitrifiers.More slow grow-ing nitrifying bacteria therefore colonized the rhizome and surface of the sediment.In THCW,the nitrogen load removal rate was about1440g N/m2 per year.As compared to other single and combined CWs(Table3), THCW exhibited higher removal rates of nitrogen than single CWs,and NH3-N removal rates were comparable to the results in the hybrid system.However,the TN removal rate was higher than that observed both in single wetland and combined systems (Cooper,1999;Platzer,1999;Kyambadde et al.,2005),suggest-Table2The amount of nitrifying bacteria and denitrifying bacteria in THCW.Bacteria Times12345MeanNitrifying bacteria(MPN/g sediment)8.89×104 2.55×105 3.67×105 3.16×105 4.23×105 2.90×105 Denitrifying bacteria(MPN/g sediment)9.12×1049.02×104 2.77×105 5.11×1057.03×105 3.34×1051048 F.Ye,Y.Li/Ecological Engineering35(2009)1043–1050Table3Removal of nitrogen in THCW and other various types of CWs.CW type Efficiency(%)in concentration(mg/L)Efficiency of TN load(g/m2/year)Ref.NH3-N TNFFP a–54.8b407b Vymazal(2007) FWS55.1c41.2d247d Vymazal(2007) SSHF48.3e42.3f250g Vymazal(2007) SSVF84.2h44.6i630j Vymazal(2007) SSVF–SSHF84––O’Hogain(2003) SSVF–SSHF78––Cooper(1999) SSHF–SSVF9761–Brix et al.(2003) SSHF–SSVF99–Laber et al.(2003) SSHF–SSVF–SSHF–SSVF–SSHF8086–Brix et al.(2003) SSVF–SSHF–FWS–65–Mander et al.(2003) SSHF–FWS–82–Masi et al.(2002) SSHF–FWS8481b–Vymazal(2005) This study(SSHF–FWS)8383(TKN)1440a Free-floating plant.b Mean values of14wetlands.c Mean values of64wetlands.d Mean values of247wetlands.e Mean values of151wetlands.f Mean values of137wetlands.g Mean values of113wetlands.h Mean values of80wetlands.i Mean values of51wetlands.j Mean values of42wetlands.ing that nitrification–denitrification coupling may be improved in this wetland.Several possible mechanisms for nitrogen removal in treatment wetlands are included,but the principal mechanism most often cited in long-term nitrogen removal is denitrification (Reed et al.,1995).The wetland also showed high nitrogen,organic matter and phosphorus removal efficiencies during the winter sea-son due to the presence of growing plants,such as Mat Rush(S. trigueter)and Pond Cypress(T.ascendens).Comparatively,this wetland exceeded reduction efficiencies of 60%reported for a FWS pilot wetland using duckweed for treat-ment of domestic primary effluent in Israel at a hydraulic load of 22cm/d with10–20%nitrogen removal and negligible phospho-rus removal(Ran et al.,2004).Although the hydraulic load was increased by about double in Phase2,TP removal efficiencies of this wetland remained high compared to Phase1and were in agreement with other studies(Kyambadde et al.,2005;Tuncsiper,2007).This supports the fact that the plants have limited ability for uptake of phosphorus nutrient and that adsorption or precipitation by bed media contributes to phosphorus removal.Phosphorus removal was also dependent on water temperature.Removal efficiencies for all measured pollutants were higher at lower hydraulic loading rates than those at higher hydraulic load-ing rates.Sun et al.(1998)had shown a decrease in organic removal with the increase in hydraulic load using an SSHF system at more than0.3kg/(m2d)hydraulic load which was similar to our wetland. However,thisfinding is in contrast to the FWS system with much lower loads.COD showed a decrease in hydraulic loads higher than 30cm/d when BOD5did not(Ran et al.,2004).This indicated that hydraulic efficiency is higher at lower hydraulic loads and varies between different configurations of CWs.COD removal rate was not as high as expected in THCW,which may be because of the bypass(about20%)of influent into the middle wetland,resulting in low HRT of this wastewater.NH3-N removal rate even at short HRT of2.7d in Phase2was comparable or greater than otherfindings in single wetlands(Kyambadde et al.,2005;Tuncsiper et al.,2006; Tuncsiper,2007).They also found that the highest removal efficien-cies were achieved at2d HRT in the SSHF,and6d HRT in the FWS and subsurfaceflow(SF)systems,suggesting that the longer HRT may be inefficient at nutrient removal.Reed and Brown(1995)sug-gested that to achieve low levels of ammonia(2mg/L)a6–8d HRT in the SF wetland must be maintained during the growing season.Commonly,the sediment is considered to be the site where the predominant denitrification occurs in wetlands.Denitrification in periphytic communities on submerged plants can make a sig-nificant contribution to overall denitrification in a wetland.PNA and PDR values obtained in THCW were higher than other reports (Bastviken et al.,2005),which perhaps contributed to higher lev-els of oxygen available for nitrifying bacteria and to the available organic carbon for denitrifying bacteria,as well as to the growth of mixed varieties plants in this wetland.Bachand and Horne(2000) noted a higher nitrate removal rate in wetlands containing mixed stands of emergent macrophytes than in those containing mono-culture.Bastviken et al.(2005)found that submerged plants exhibit a considerably higher denitrifying capacity than emergent plants. Although the macrophytes in this THCW were all emergent plants and a part of plants were harvested,the below-ground portion of the plants still remained in the wetland;these may provide organic carbon and be a suitable surface for bacterial attach-ment.DNA–DNA hybridization data indicated that most bacteria of the total population lived in the upper(5cm)soil layer.Hybridizations with all denitrification probes also showed that denitrifying bac-teria are enriched in the vicinity of plant roots,as compared to bulk,root-free soil(Joergensen,1989).So the sediments for nitri-fying and denitrifying bacteria measurements were removed from the sediment–water interface(0–2cm),and from a deeper level (5–8cm),paring the performance of the wetland over time,it suggested that microbial activity along with loading change was a little lag,and was not an accurate parameter.Higher DO concentration due to passive oxygenation resulting from the cascade current in the second stage of THCW may be contribut-ing to the higher PDR,and approximately two orders of magnitude higher numbers of nitrifying bacteria,and comparable denitrifying bacteria in this study as compared to that found in other reports (Bastviken et al.,2003;He et al.,2004).In sediments of a Danish fjord estuary,denitrification activity determined by15N isotope measurements and by the acetylene inhibition technique showed that denitrification capacity was high-。
土木工程--毕业设计外文翻译(原文+翻译)
毕业设计（论文）外文翻译题目西北物流中心2号楼设计专业土木工程班级土木074学生指导教师二零一零年Low-coherence deformation sensors for themonitoring of civil-engineering structuresD. Inaudi a, A. Elamari b, L. Pflug a, N. Gisin b, J. Breguet b, S. Vurpillot a “IMAC, Laboratory of Stress Analysis, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland ‘GAP, Group of Applied Physics -Optical Seciion, Geneva University CH-1205 Geneva, SwitzerlandRcccivcd 25 January 1993; in revised form 8 March 1994; accepted 25 March 1994 AbstractAn optical-fiber deformation sensor with a resolution of 10 pm and an operational range of 60 mm has been realized. The system is based on low-coherence interferometry instandard single-mode telecommunication fibers. It allows the monitoring of large structures over several months without noticeable drift. No continuous measurement is needed and the system is insensitive to variations of the fiber losses. This technique has been applied to the monitoring of a 20 m X5 m X0.5 m, 120 ton concrete slab over six months. It is possible to measure the shrinkage of concrete and its elastic coefficient during pre-straining, giving reproducible results in good agreement with theoretical calculations and measurements performed on small concrete samples. This paper describes the optical arrangement and the procedures used to install optical fibers in concrete.Keywor&: Ikformation sensors; Civil-engineering structures1. IntroductionBoth the security of civil-engineering works and the law require a periodic monitoring of structures. The methods used for this purpose, such as triangulation, water levels or vibrating strings, are often of tedious application and require one or many specialized operators. This complexity and the resulting costs limit the frequency of the measurements. Furthermore, the spatial resolution is often poor and the observation is usually restricted to the surface of the object. There is thus a real demand for a tool allowing an internal, automatic and permanent monitoring of structures with high accuracy and stability over periods typically of the order of 100 years for bridges. In this framework, fiber-optic smart structures (i.e., structures with self-testing capabilities) are gaining in importance in many fields including aeronautics and composite material monitoring. This technology can be applied in civilengineering and in particular for the short- and long-time observation of large structures such as bridges, tall building frames, dams, tunnels, roads, airport runways, domes, pre-stressing and anchorage cables. The monitoring of such structures requires the development of a measuring technique with high accuracy,stability and reliability over long periods. It has to beindependent of variations in the fiber losses and adapted to the adverse environment of a building site. To reduce the cost of the instrumentation, it is furthermore desirable to use the same portable reading unit for the monitoring of multiple structures. We describe here asystem based on low-coherence interferometry responding to all these requirements.2. Experimental arrangementThe measuring technique relies on an array of standard telecommunication optical fibers in mechanical contact with concrete. Any deformation of the host structure results jn a change in the optical length of he fibers. Each sensor line consists of two single-mode ibers: one measurement fiber in mechanical contact with the structure (glued or cemented) and a reference iber placed loose near the first one (in a pipe) in order to be at the same temperature. Since the measurement technique monitors the length difference beween these two fibers, only the mechanical deformation will have an effect on the results while all other perurbations, such as thermally induced changes in the refractive index of the fibers,will affect the two in an identical way and cancel each another out. To measure the optical path difference between the two fibers, a low-coherence double interferometer in tandem configuration has been used (Fig. 1) [l]. The source is an LED (light-emitting diode) working around 1.3 pm with a coherence length L, of 30 pm and a rated power of 200 pW. The radiation is launched into a single-mode fiber and then directed toward the measurement and the reference fibers by means of a 50:50 single-mode directional coupler. At the ends of the fibers two mirrors reflect the light back to the coupler, where the beams arc recombined with a relative delay due to the length difference AL, between the fibers, and then directed towards the second (reference) interferometer. The reference interferometer is of Michelson type with one of the arms ended by a mobile mirror mounted on a micromctric displacement table with a resolution of 0.1 pm and an operating range of 50 mm. It allows the introduction of an exactly known path difFcrence AL, between its two arms. This fiber interferometer is portable and needs no optical adjustment after transportation. It has been developed by the GAP with the support of the Swiss PTT for optical cable testing [2].The intensity at the output of the reference inter- ferometer is measured with a pig-tail photodiode and is then given by [3]where zz,,r is the effective refractive index of the fiber, zzg the group refractive index (about 1% higher than nefr in silica), A, the central vacuum wavelength of the light, zi,, the autocorrelation function taking the spectral characteristics of the emission into account and AL the physical path difference between the two interfering paths. Further similar interference terms appear in Eq.(1) in the special cases when AL, <L, or AL, < L,. When the optical path difference between the arms in the reference interferometer corresponds to the one induced by the two fibers installed in the structure (within the coherence length of the source), interference fringes appear. Scanning AL, with the mirror of the reference interferometer it is possible to obtain AL = 0either with AL, = AL, or with AL, = -AL,, and thus two interference fringe packets as described by Eq. (1). The mirror position corresponding to AL, = 0 also produces an interference and is used as a reference. These three fringe packets arc detected by means of a lock-in amplifier synchronized with the mirror displacements. The mirror displacements and the digitalization of the lock-in output are carried out by means of a portable personal computer. Since the reference signal is gcnerated separately and does not have a constant phase relation to the interference signal, only the envelope of the demodulated signal has a physical meaning and corresponds to the envelope of the fringe pattern. A lock-in plot showing the three typical peaks is shown in Fig. 2. Each peak has a width of about 30 pm. The calculation of its center of gravity determines its position with a precision better than 10 pm. This precision is the limiting factor of the whole measurement technique. Since AL, is known with micrometer precision, it is possible to follow AL, with the same precision.Fig. 1. Experimental setup of the low-coherence double Michelson interferomctcr. D. Innudi et al. 1 Semors andFig. 2. Typical fringe cnvclope as a function of the mirror position. The distance between the central and the lateral peaks corresponds to the length difference between the measurement and the reference fibers mounted in the table. Any change in the length of the structure results in a change in the position of these peaks. Any change in the losses of the fibers will result in a change of the height of the peaks. The central peak is fixed and used as a reference.The path difference AL, is proportional to the de-formation of the structure AL, with the relation between the two given by [4]where p is Poisson’s ratio and pij is the strain optic tensor (Pockcl’s coefhcients). The coefficient 5 takes into account the variation of the effective index neff in a fiber under strain.A degradation of one or both fibers (due to aging, for example) will result in a lower visibilityof the fringes but will not affect its position. The information about the deformation of the structure is encoded in the coherence properties of light and not in its intensity as in the majority of the sensors applied to date in civil-engineering structures, mostly based on microbend losses and/or optical time-domain reflectometry (OTDR) techniques. Interference peaks resulting from reflections as low as -30 dB of the source power can be detected by our system without phase modulators. By modulating the phase in one of the four arms of the two interferometers, one can increase the dynamic range of the device to more than 100 dB [5].Even if the polarization dispersion and bend-induced birefringence in the sensing fibers could reduce the visibility of the interference fringes or even split the fringe packets, none of those effects was observed in our experiment. No adjustment of polarization between the reference and the sensing arm was then necessary. A good mechanical contact between the measurement fiber and the structure under test is fundamental. In this study a number of installation procedures have been tested and optimized for the different measurements (shrinkage, elasticity modulus, etc.). The mounting techniques can be divided into two main categories: full-length coupling and local coupling.During our tests five out of six optical fiber pairs with a 0.9 mm nylon coating, being mounted on the external face of a 20 m long plastic pipe and protected only with thin rubber bands (see Fig. 3(a)), survived the concreting process. During the setting process the concrete envelops the fiber and realizes the desired mechanical contact. Those fibers showed a minor increase in the scattering losses and the appearance of small parasite peaks. The measurements on those fibers were consistent with the results obtained with other installation techniques (see below). It seems that for full-length coupling the nylon coating transmits the structure deformations (extension and shortening) entirely to the fiber core. This installation technique is very promising when compared to the usual procedure, consisting of a pipe protecting the fibers during the pouring of concrete and being removed before the setting process begins. This second method seemsmore adapted to small samples than to full-scale structures. Eleven otherfiber pairs were glued at the two ends of the table after removing locally the protective coating layers of the fibers (see Fig. 3(b)). The silica fiber was ftxed with epoxy glue to a metallic plate mounted on the end facesof the concrete structure. The gluing length was about 20 mm. Apre-strain (between 0.1 and 0.4%) has been given to those fibers during the gluing process to keep them under tension and allow the measurement of both expansion and shrinkage of the structure. This type of local coupling proved to be the most reliable, but was not adapted to following thedeformation during the pre-stressing of the table because of the important surface deformations occurring during this operation. The problem has been overcome by gluing other fibers inside the pipes at about two meters from the surfaces, i.e., far from the force insertion region (see Fig. 3(c)).Fig. 3. Schematic representation of three of the installation techniques used:(a) direct concreting of the measurement fiber mounted on a plastic pipe; (b) fiber glued at the table surface; (c) fiber glued inside the pipe at 2m from the pipe ends.Fig. 4. Top and side views of the concrete table measured in the experiment and position of the sensing-fiber pairs A, B, C and D. Fibers A, B and C arc glued at the surface of the structure, while fiber D is glued inside a pipe, 2 m away from the surface of the slab. Twelve more fihcr pairs were installed, but are not shown for simplicity.To study the possible effect of creep in strained fibers [6], one fiber has been mounted on a mechanical support that allows the fiber to be tightened only at the time of the measurement. No difference between this fiberand those permanently strained has been observed over a period of six months, confirming the assumption that no creep occurs for fiber strains below 1%. Since the scanning range of the mirror is 5 mm, it was easy to cleave the 20 m long fibers within this margin. The Fresnel reflection of the cleaved fibers combined with the high dynamic of the system allow a measurement of AL,,. This value of AL, can than be used to correct the cutting and obtain pairs with length differences below 1 mm. Two ferrules were then installed on the fiber ends and mounted in front of a polished inox surface. Chemical silver deposition was also used to produce mirrors on the cleaved fiber ends.Fig. 6. Comparison between the measurements performed on the structure by optical fibers and the ones performed on 360 mm and 500 mm samples in a mechanical micrometer comparator. The measurement on the samples was possible only during the first two months.3. ResultsSeveral long- and short-term measurements have been carried on a 20 m x 5 m x 0.5 m, 120 ton concrete slab intended to be used as a vibration-isolated base for optical analysis (in particular by holographic and speckle interferometry) of large structures [7].This structure has been concreted indoors, allowing controlled environmcntal conditions and known concrete composition to be achieved. Samples have been prepared with the same material composition and are under permanent test for their mechanical properties (resistance, shrinkage and elastic coefficient). This allows a direct comparison between the results on the full-scale structure and the samples. The table has been pre-strained 23 days after concreting in both length and width. It was possible at this time to measure the elastic coefficient of the material in full scale. Fig. 4 shows a schematic representation of the table and the position of the fibers referred to in the experimental results. At the time of writing, the table has been under test for six months. Over this period the shrinkage in the longitudinal direction (i.e., over 20 m) has been about 6 mm. We show in Fig. 5 the results of the measurements for three (glued) fibers over 175 days. The table has a T profile (Fig. 4). It is evident from Fig. 5 that thefibers mounted near the borders of the table, i.e., were the thickness is smaller, registered a larger shrinkage, as expected according to the concrete theory. Adjacentfibers give consistent results independently of the installation technique. No difference has been noticed between the fibers under permanent tension and those loosened between the measurements, suggesting that no creep of glass fibers occurred. The shrinkage measured with the fiber system has been compared during the first two months with the results obtained with a mechanical comparator mounted on two samples of 360 mm and 500 mm, respectively.The observed deformations have been scaled to 20m and are compared in Fig.6 to the results obtained with fibers B and C. Very good agreement is found between the two measurements. A theoretical comparison between the experimentalresults and the Swiss civil engineering standards has also been carried out. The experimental data and the standards are in agreement within f 10%. A more accurate simulation including the physico-chemical properties of the concrete used is under development. The table was pre-stressed 23 days after concreting. The five steel cables running over the length of the table and the forty cables running over its width were stretched with a force of 185 kN (18.5 Tons) each. The fibers glued to the surface and those in direct contact with concrete over the whole length measured an expansion of the table instead of the expected shrinkage. This is due to the important surface deformations occurring near the force-insertion points, i.e., near the pre-stress heads that were placed near the fiber ends. Fiber D glued inside the plastic pipe at 2m from each endwas not subject to these local effects and measured a shortening of 0.23 mm. The theoretical calculation based on an elastic coefficient of 30 kN/mm2gives a shortening of 0.28mm at the borders and 0.19 mm at the center of the table. Since fiber D was placed in an intermediate position, the experimental value can be considered to be in good agreement with the theory.4. ConclusionsA new deformation sensor adapted to the monitoring of civil-engineering structures has been proposed. it is based on low-coherence interferometry in standard lowcost telecommunication fibers. The resolution of the measurements is 10 pm, the operational range is 60mm and the stability has been tested over six months without noticeable drift. The reading unit is compact and portable, needing no optical alignment before the measurements. It is controlled by a portable personal computer, which is also responsible for the data trcatment. The same reading unit can be used to monitor multiple fiber lines by simple manual unplugging. This technique is furthermore practically insensitive to increased losses due to degradation of the fibers. A test study has been carried out on a 20m ~5m X 0.5m concrete slab, giving consistent results when compared to other measurement techniques based on samples or to concrete theories. It was possible to follow concrete shrinkage over six months (the cxper- iment will continue for about five years) and to measure the elastic coefficient on the full-scale structure. Different fiber-installation techniques adapted to the measurement of various parameters have been tested in building-site conditions. This technique appears very promising for the mon-itoring of civil-engineering structures such as bridges, dams and tunnels, allowing internal, automatic and permanent monitoring with high precision and stability over long periods.AcknowledgmentsThe authors are indebted to R. Passy and R. Delez for their assistance, encouragement and helpful dis-cussion. We acknowledge the IMM Institute in Lugano (Switzerland) for placing the table at our disposal and for the measurements carried out on concrete samples. We are grateful to Dr M. Pedretti and Ing R. Passera for their personal engagement in the project. We also thank Cabloptic in Cortaillod (Switzerland) for sup-plying all the optical fibers used in the experiment. This research has been performed with the financial support of CERS (Commission pour 1’Encouragement de la Recherche Scientifique).References[1] A.Koch and R.Ulrich,Fiber optic displacement sensor with 0.02mm resolutionbuy white-light interferometry,sensors and actuators A,25-27(1991)201-207[2]N.Gisin,J.-P.Von der weid and J.-P.Pellaux,Polarization mode dispersion ofshort and long single-mode fibers,J.Lightwave technol,9(1991)821-827.[3] A.S.Gergcs,F.Farahi,T.P.Newson,J.D.C.Jones and D.A.Jackson, Fiber-opticinterferometric sensors using low coherence source:dynamic range enhancement,Int. J.Op-toelectron,3(1988)311-322.[4] C.D.Butter and G.B.Hacker, Fiber optics strain gauge,Appl.Opt,17(1978)2867-2869.[5]H.H.Gilger,G.Bodmer and Ch.Zimmer, Optical coherance domain retlectometry asa test method of integrated optics devices,Proc.2nd Opt. Fibre Meas. Conf:OFMC 93, Turin, Ztuly, Z993, pp.143-146.[6]J.-P.Jaguin and A.Zaganiaris,La mecanique de rupture appliquee aux fibresoptiques, Verres Refract, 34 (Jul-Aout)(1980).[7]L.Pflug and M.Pedretti, Construction of a loo-tonnes holographictable,ZS&TISPIE Znt.Symp. Electronic Imaging, SanJose,CA,USA,1993,pp.50-54.传感器和执行器 A 44（1994）12.5-130用低变形传感器监测民用工程结构变形的一致性D.Inaudi a, A.Elamari b, L.Pflug b, N.Gisin b, J.Breguet b, S.Vurpillot aa IMAC、实验室的应力分析,瑞士联邦理工学院,CH-1015瑞士洛桑b GAP,群应用物理-光学部分,日内瓦大学，CH-1205瑞士日内瓦举行1993年1月25日实验;1994年3月8日修订,1994年3月25日发表文摘一个光纤变形的分辨率的传感器,10µm和运行范围的60毫米已经实现了。
土木工程毕业设计 外文翻译
外文原文Talling Building And Steel Construction Although there have been many advancements in building construction technology in general. Spectacular archievements have been made in the design and construction of ultrahigh-rise buildings. The early development of high-rise buildings began with structural steel framing.Reinforced concrete and stressed-skin tube systems have since been economically and competitively used in a number of structures for both residential and commercial purposes.The high-rise buildings ranging from 50 to 110 stories that are being built all over the United States are the result of innovations and development of new structual systems.Greater height entails increased column and beam sizes to make buildings more rigid so that under wind load they will not sway beyond an acceptable limit.Excessive lateral sway may cause serious recurring damage to partitions,ceilings.and other architectural details. In addition,excessive sway may cause discomfort to the occupants of the building because their perception of such motion.Structural systems of reinforced concrete,as well as steel,take full advantage of inherent potential stiffness of the total building and therefore require additional stiffening to limit the sway.Systems in concrete. While tall buildings constructed of steel had an early start, development of tall buildings of reinforced concrete progressed at a fast enough rate to provide a competitive chanllenge to structural steel systems for both office and apartment buildings.Framed tube. As discussed above, the first framed tube concept for tall buildings was used for the 43-story DeWitt Chestnut Apartment Building. In this building ,exterior columns were spaced at 5.5ft (1.68m) centers, and interior columns were used as needed to support the 8-in . -thick (20-m) flat-plate concrete slabs.Tube in tube. Another system in reinforced concrete for officebuildings combines the traditional shear wall construction with an exterior framed tube. The system consists of an outer framed tube of very closely spaced columns and an interior rigid shear wall tube enclosing the central service area. The system (Fig .2), known as the tube-in-tube system , made it possible to design the world’s present tallest (714ft or 218m)lightweight concrete building ( the 52-story One Shell Plaza Building in Houston) for the unit price of a traditional shear wall structure of only 35 stories.Systems combining both concrete and steel have also been developed, an examle of which is the composite system developed by skidmore, Owings &Merril in which an exterior closely spaced framed tube in concrete envelops an interior steel framing, thereby combining the advantages of both reinforced concrete and structural steel systems. The 52-story One Shell Square Building in New Orleans is based on this system.In a steel structure,for example,the economy can be defined in terms of the total average quantity of steel per square foot of floor area of the building.Curve A in Fig .1 represents the average unit weight of a conventional frame with increasing numbers of stories. Curve B represents the average steel weight if the frame is protected from all lateral loads. The gap between the upper boundary and the lower boundary represents the premium for height for the traditional column-and-beam frame.Structural engineers have developed structural systems with a view to eliminating this premium. Systems in steel. Tall buildings in steel developed as a result of several types of structural innovations. The innovations have been applied to the construction of both office and apartment buildings.Frame with rigid belt trusses. In order to tie the exterior columns of a frame structure to the interior vertical trusses,a system of rigid belt trusses at mid-height and at the top of the building may be used.A good example of this system is the First Wisconsin Bank Building(1974) in Milwaukee.Framed tube. The maximum efficiency of the total structure of a tallbuilding, for both strength and stiffness,to resist wind load can be achieved only if all column element can be connected to each other in such a way that the entire building acts as a hollow tube or rigid box in projecting out of the ground. This particular structural system was probably used for the first time in the 43-story reinforced concrete DeWitt Chestnut Apartment Building in Chicago. The most significant use of this system is in the twin structural steel towers of the 110-story World Trade Center building in New York.Column-diagonal truss tube. The exterior columns of a building can be spaced reasonably far apart and yet be made to work together as a tube by connecting them with diagonal members interesting at the centre line of the columns and beams. This simple yet extremely efficient system was used for the first time on the John Hancock Centre in Chicago, using as much steel as is normally needed for a traditional 40-story building.Bundled tube. With the continuing need for larger and taller buildings, the framed tube or the column-diagonal truss tube may be used in a bundled form to create larger tube envelopes while maintaining high efficiency. The 110-story Sears Roebuck Headquarters Building in Chicago has nine tube, bundled at the base of the building in three rows. Some of these individual tubes terminate at different heights of the building, demonstrating the unlimited architectural possibilities of this latest structural concept. The Sears tower, at a height of 1450 ft(442m), is the world’s tallest building.Stressed-skin tube system. The tube structural system was developed for improving the resistance to lateral forces (wind and earthquake) and the control of drift (lateral building movement ) in high-rise building. The stressed-skin tube takes the tube system a step further. The development of the stressed-skin tube utilizes the façade of the building as a structural element which acts with the framed tube, thus providing an efficient way of resisting lateral loads in high-rise buildings, and resulting in cost-effective column-free interior space with a high ratioof net to gross floor area. Because of the contribution of the stressed-skin façade, the framed members of the tube require less mass, and are thus lighter and V less expensive. All the typical columns and spandrel beams are standard rolled shapes,minimizing the use and cost of special built-up members. The depth requirement for the perimeter spandrel beams is also reduced, and the need for upset beams above floors, which would encroach on valuable space, is minimized. The structural system has been used on the 54-story One Mellon Bank Center in Pittburgh.Steel construction refers to a broad range of building construction in which steel plays the leading role. Most steel construction consists of large-scale buildings or engineering works, with the steel generally in the form of beams, girders, bars, plates, and other members shaped through the hot-rolled process. Despite the increased use of other materials, steel construction remained a major outlet for the steel industries of the U.S, U.K, U.S.S.R, Japan, West German, France, and other steel producers in the 1970s.Early history. The history of steel construction begins paradoxically several decades before the introduction of the Bessemer and the Siemens-Martin (openj-hearth) processes made it possible to produce steel in quantities sufficient for structure use. Many of problems of steel construction were studied earlier in connection with iron construction, which began with the Coalbrookdale Bridge, built in cast iron over the Severn River in England in 1777. This and subsequent iron bridge work, in addition to the construction of steam boilers and iron ship hulls , spurred the development of techniques for fabricating, designing, and jioning. The advantages of iron over masonry lay in the much smaller amounts of material required. The truss form, based on the resistance of the triangle to deformation, long used in timber, was translated effectively into iron, with cast iron being used for compression members-i.e, those bearing the weight of direct loading-and wrought iron being used for tension members-i.e, those bearing the pull of suspendedloading.The technique for passing iron, heated to the plastic state, between rolls to form flat and rounded bars, was developed as early as 1800;by 1819 angle irons were rolled; and in 1849 the first I beams, 17.7 feet (5.4m) long , were fabricated as roof girders for a Paris railroad station.Two years later Joseph Paxton of England built the Crystal Palace for the London Exposition of 1851. He is said to have conceived the idea of cage construction-using relatively slender iron beams as a skeleton for the glass walls of a large, open structure. Resistance to wind forces in the Crystal palace was provided by diagonal iron rods. Two feature are particularly important in the history of metal construction; first, the use of latticed girder, which are small trusses, a form first developed in timber bridges and other structures and translated into metal by Paxton ; and second, the joining of wrought-iron tension members and cast-iron compression members by means of rivets inserted while hot.In 1853 the first metal floor beams were rolled for the Cooper Union Building in New York. In the light of the principal market demand for iron beams at the time, it is not surprising that the Cooper Union beams closely resembled railroad rails.The development of the Bessemer and Siemens-Martin processes in the 1850s and 1860s suddenly open the way to the use of steel for structural purpose. Stronger than iron in both tension and compression ,the newly available metal was seized on by imaginative engineers, notably by those involved in building the great number of heavy railroad bridges then in demand in Britain, Europe, and the U.S.A notable example was the Eads Bridge, also known as the St. Louis Bridge, in St. Louis (1867-1874), in which tubular steel ribs were used to form arches with a span of more than 500ft (152.5m). In Britain, the Firth of Forth cantilever bridge (1883-90) employed tubular struts, some 12 ft (3.66m) in diameter and 350 ft (107m) long. Such bridges and other structures were important in leading to the development and enforcementof standards and codification of permissible design stresses. The lack of adequate theoretical knowledge, and even of an adequate basis for theoretical studies, limited the value of stress analysis during the early years of the 20th century,as iccasionally failures,such as that of a cantilever bridge in Quebec in 1907,revealed.But failures were rare in the metal-skeleton office buildings;the simplicity of their design proved highly practical even in the absence of sophisticated analysis techniques. Throughout the first third of the century, ordinary carbon steel, without any special alloy strengthening or hardening, was universally used.The possibilities inherent in metal construction for high-rise building was demonstrated to the world by the Paris Exposition of 1889.for which Alexandre-Gustave Eiffel, a leading French bridge engineer, erected an openwork metal tower 300m (984 ft) high. Not only was the height-more than double that of the Great Pyramid-remarkable, but the speed of erection and low cost were even more so, a small crew completed the work in a few months.The first skyscrapers. Meantime, in the United States another important development was taking place. In 1884-85 Maj. William Le Baron Jenney, a Chicago engineer , had designed the Home Insurance Building, ten stories high, with a metal skeleton. Jenney’s beams were of Bessemer steel, though his columns were cast iron. Cast iron lintels supporting masonry over window openings were, in turn, supported on the cast iron columns. Soild masonry court and party walls provided lateral support against wind loading. Within a decade the same type of construction had been used in more than 30 office buildings in Chicago and New York. Steel played a larger and larger role in these , with riveted connections for beams and columns, sometimes strengthened for wind bracing by overlaying gusset plates at the junction of vertical and horizontal members. Light masonry curtain walls, supported at each floor level, replaced the old heavy masonry curtain walls, supported at each floor level , replaced the old heavy masonry.Though the new construction form was to remain centred almost entirely in America for several decade, its impact on the steel industry was worldwide. By the last years of the 19th century, the basic structural shapes-I beams up to 20 in. ( 0.508m) in depth and Z and T shapes of lesser proportions were readily available, to combine with plates of several widths and thicknesses to make efficient members of any required size and strength. In 1885 the heaviest structural shape produced throughhot-rolling weighed less than 100 pounds (45 kilograms) per foot; decade by decade this figure rose until in the 1960s it exceeded 700 pounds (320 kilograms) per foot.Coincident with the introduction of structural steel came the introduction of the Otis electric elevator in 1889. The demonstration of a safe passenger elevator, together with that of a safe and economical steel construction method, sent building heights soaring. In New York the 286-ft (87.2-m) Flatiron Building of 1902 was surpassed in 1904 by the 375-ft (115-m) Times Building ( renamed the Allied Chemical Building) , the 468-ft (143-m) City Investing Company Building in Wall Street, the 612-ft (187-m) Singer Building (1908), the 700-ft (214-m) Metropolitan Tower (1909) and, in 1913, the 780-ft (232-m) Woolworth Building.The rapid increase in height and the height-to-width ratio brought problems. To limit street congestion, building setback design was prescribed. On the technical side, the problem of lateral support was studied. A diagonal bracing system, such as that used in the Eiffel Tower, was not architecturally desirable in offices relying on sunlight for illumination. The answer was found in greater reliance on the bending resistance of certain individual beams and columns strategically designed into the skeletn frame, together with a high degree of rigidity sought at the junction of the beams and columns.With today’s modern interior lighting systems, however, diagonal bracing against wind loads has returned; one notable example is the John Hancock Center in Chicago, where the external X-braces form a dramatic part of the structure’s façade.World War I brought an interruption to the boom in what had come to be called skyscrapers (the origin of the word is uncertain), but in the 1920s New York saw a resumption of the height race, culminating in the Empire State Building in the 1931. The Empire State’s 102 stories (1,250ft. [381m]) were to keep it established as the hightest building in the world for the next 40 years. Its speed of the erection demonstrated how thoroughly the new construction technique had been mastered. A depot across the bay at Bayonne, N.J., supplied the girders by lighter and truck on a schedule operated with millitary precision; nine derricks powerde by electric hoists lifted the girders to position; an industrial-railway setup moved steel and other material on each floor. Initial connections were made by bolting , closely followed by riveting, followed by masonry and finishing. The entire job was completed in one year and 45 days.The worldwide depression of the 1930s and World War II provided another interruption to steel construction development, but at the same time the introduction of welding to replace riveting provided an important advance.Joining of steel parts by metal are welding had been successfully achieved by the end of the 19th century and was used in emergency ship repairs during World War I, but its application to construction was limited until after World War II. Another advance in the same area had been the introduction of high-strength bolts to replace rivets in field connections.Since the close of World War II, research in Europe, the U.S., and Japan has greatly extended knowledge of the behavior of different types of structural steel under varying stresses, including those exceeding the yield point, making possible more refined and systematic analysis. This in turn has led to the adoption of more liberal design codes in most countries, more imaginative design made possible by so-called plastic design ?The introduction of the computer by short-cutting tedious paperwork, made further advances and savings possible.中文翻译高层结构与钢结构近年来，尽管一般的建筑结构设计取得了很大的进步，但是取得显著成绩的还要属超高层建筑结构设计。
土木工程毕业设计外文翻译
Create and comprehensive technology in the structure globaldesign of the buildingThe 21st century will be the era that many kinds of disciplines technology coexists , it will form the enormous motive force of promoting the development of building , the building is more and more important too in global design, the architect must seize the opportunity , give full play to the architect's leading role, preside over every building engineering design well. Building there is the global design concept not new of architectural design,characteristic of it for in an all-round way each element not correlated with building- there aren't external environment condition, building , technical equipment,etc. work in coordination with, and create the premium building with the comprehensive new technology to combine together.The premium building is created, must consider sustainable development , namely future requirement , in other words, how save natural resources as much as possible, how about protect the environment that the mankind depends on for existence, how construct through high-quality between architectural design and building, in order to reduce building equipment use quantity and reduce whole expenses of project.The comprehensive new technology is to give full play to the technological specialty of every discipline , create and use the new technology, and with outside space , dimension of the building , working in coordination with in an all-round way the building component, thus reduce equipment investmentand operate the expenses.Each success , building of engineering construction condense collective intelligence and strength; It is intelligence and expectation that an architect pays that the building is created; The engineering design of the building is that architecture , structure , equipment speciality compose hardships and strength happenning; It is the diligent and sweat paid in design and operation , installation , management that the construction work is built up .The initial stage of the 1990s, our understanding that the concept of global design is a bit elementary , conscientious to with making some jobs in engineering design unconsciously , make some harvest. This text Hangzhou city industrial and commercial bank financial comprehensive building and Hangzhou city Bank of Communications financial building two building , group of " scientific and technological progress second prize " speak of from person who obtain emphatically, expound the fact global design - comprehensive technology that building create its , for reach global design outstanding architect in two engineering design, have served as the creator and persons who cooperate while every stage design and even building are built completely.Two projects come into operation for more than 4 years formally , run and coordinate , good wholly , reach the anticipated result, accepted and appreciated by the masses, obtain various kinds of honor .outstanding to design award , progress prize in science and technology , project quality bonus , local top ten view , best model image award ,etc., the ones that do not give tothe architect and engineers without one are gratified and proud. The building is created Emphasizing the era for global design of the building, the architects' creation idea and design method should be broken through to some extent, creation inspirations is it set up in analysis , building of global design , synthesize more to burst out and at the foundation that appraise, learn and improve the integration capability exactly designed in building , possess the new knowledge system and thinking method , merge multi-disciplinary technology. We have used the new design idea in above-mentioned projects, have emphasized the globality created in building .Is it is it act as so as to explain to conceive to create two design overview and building of construction work these now.1) The financial comprehensive building of industrial and commercial bank of HangZhou, belong to the comprehensive building, with the whole construction area of 39,000 square meters, main building total height 84, 22, skirt 4 of room, some 6 storeys, 2 storeys of basements.Design overall thinking break through of our country bank building traditional design mode - seal , deep and serious , stern , form first-class function, create of multi-functional type , the style of opening , architecture integrated with the mode of the international commercial bank.The model of the building is free and easy, opened, physique was made up by the hyperboloid, the main building presented " the curved surface surrounded southwards ", skirt room presents " the curved surface surrounded northwards ",the two surround but become intension of " gathering the treasure ".Building flourishing upwards, elevation is it adopt large area solid granite wall to design, the belt aluminium alloy curtain wall of the large area and some glass curtain walls, and interweave the three into powerful and vigorous whole , chase through model and entity wall layer bring together , form concise , tall and straight , upward tendency of workingup successively, have distinct and unique distinctions.Building level and indoor space are designed into a multi-functional type and style of opening, opening, negotiate , the official working , meeting , receiving , be healthy and blissful , visit combining together. Spacious and bright two storeys open in the hall unifiedly in the Italian marble pale yellow tone , in addition, the escalator , fountain , light set off, make the space seem very magnificent , graceful and sincere. Intelligent computer network center, getting open and intelligent to handle official business space and all related house distribute inall floor reasonably. Top floor round visit layer, lift allof Room visit layer , can have a panoramic view of the sceneryof the West Lake , fully enjoy the warmth of the nature. 2) The financial building of Bank of Communications of Hangzhou, belong to the purely financial office block, with the whole construction area of 19,000 square meters, the total heightof the building is 39.9 meters, 13 storeys on the ground, the2nd Floor. Live in building degree high than it around location , designer have unique architectural appearance of style architectural design this specially, its elevation is designed into a new classical form , the building base adoptsthe rough granite, show rich capability , top is it burn granite and verticality bar and some form aluminum windows make up as the veneer to adopt, represent the building noble and refined , serious personality of the bank.While creating in above-mentioned two items, besides portraying the shape of the building and indoor space and outside environment minister and blending meticulously, in order to achieve the outstanding purpose of global design of the building , the architect , still according to the region and project characteristic, put forward the following requirement to every speciality:(1) Control the total height of the building strictly;(2) It favorable to the intelligent comfortableheight of clearances to create; (3) Meet the floor area of owner's demand;(4)Protect the environment , save the energy , reduce and make the investment;(5) Design meticulously, use and popularize the newtechnology; (6) Cooperate closely in every speciality, optimization design.Comprehensive technologyThe building should have strong vitality, there must be sustainable development space, there should be abundant intension and comprehensive new technology. Among above-mentioned construction work , have popularized and used the intelligent technology of the building , has not glued and formed the flat roof beam of prestressing force - dull and stereotyped structure technology and flat roof beam structure technology, baseplate temperature mix hole , technology of muscle and base of basement enclose newtechnology of protecting, computer control STL ice hold cold air conditioner technology, compounding type keeps warm and insulates against heat the technology of the wall , such new technologies as the sectional electricity distribution room ,etc., give architecture global design to add the new vitality of note undoubtedly.1, the intelligent technology of the buildingIn initial stage of the 1990s, the intelligent building was introduced from foreign countries to China only as a kind of concept , computer network standard is it soon , make information communication skeleton of intelligent building to pursue in the world- comprehensive wiring system becomes a kind of trend because of 10BASE-T. In order to make the bank building adapt to the development of the times, the designer does one's utmost to recommend and design the comprehensive wiring system with the leading eyes , this may well be termed the first modernized building which adopted this technical design at that time.(1) Comprehensive wiring system one communication transmission network, it make between speech and data communication apparatus , exchange equipment and other administrative systems link to each other, make the equipment and outside communication network link to each other too. It include external telecommunication connection piece and inside information speech all cable and relevant wiring position of data terminal of workspace of network. The comprehensive wiring system adopts the products of American AT&T Corp.. Connected up the subsystem among the subsystem , management subsystem , arterial subsystem and equipment to make up by workspace subsystem , level.(2) Automated systems of security personnel The monitoring systems of security personnel of the building divide into the public place and control and control two pieces of system equipment with the national treasury special-purposly synthetically.The special-purpose monitoring systems of security personnel of national treasury are in the national treasury , manage the storehouse on behalf of another , transporting the paper money garage to control strictly, the track record that personnel come in and go out, have and shake the warning sensor to every wall of national treasury , the camera, infrared microwave detector in every relevant rooms, set up the automation of controlling to control.In order to realize building intellectuality, the architect has finished complete indoor environment design, has created the comfortable , high-efficient working environment , having opened up the room internal and external recreation space not of uniform size, namely the green one hits the front yard and roofing, have offered the world had a rest and regulated to people working before automation is equipped all day , hang a design adopt the special building to construct the node in concrete ground , wall at the same time.2, has not glued and formed the flat roof beam of prestressing force- dull and stereotyped structure technology and flat roof beam structure technology In order to meet the requirement with high assurance that the architect puts forward , try to reduce the height of structure component in structure speciality, did not glue and form the flat roof beam of prestressing force concrete - dulland stereotyped structure technology and flat roof beam structure technology after adopting.(1) Adopt prestressing force concrete roof beam board structure save than ordinary roof beam board concrete consumption 15%, steel consumption saves 27%, the roof beam reduces 300mm high.(2) Adopt flat roof beam structure save concrete about 10% consumption than ordinary roof beam board, steel consumption saves 6.6%, the roof beam reduces 200mm high.Under building total situation that height does not change , adopt above-mentioned structure can make the whole building increase floor area of a layer , have good economic benefits and social benefit.3, the temperature of the baseplate matches muscle technologyIn basement design , is it is it is it after calculating , take the perimeter to keep the construction technology measure warm to split to resist to go on to baseplate, arrange temperature stress reinforcing bar the middle cancelling , dispose 2 row receives the strength reinforcing bar up and down only, this has not only save the fabrication cost of the project but also met the basement baseplate impervious and resisting the requirement that splits.4, the foundation of the basement encloses and protects the new technology of design and operationAdopt two technological measures in enclosing and protecting a design:(1) Cantilever is it is it hole strength is it adopt form strengthen and mix muscle technology to design to protect to enclose, save the steel and invite 60t, it invests about280,000 to save.(2) Is it is it protect of of elevation and keep roof beam technology to enclose , is it protect long to reduce 1.5m to enclose all to reduce, keep roof beam mark level on natural ground 1.5m , is it is it protect of lateral pressure receive strength some height to enclose to change, saving 137.9 cubic meters of concrete, steel 16.08t, reduces and invests 304,000 yuan directly through calculating.5, ice hold cold air conditioner technologyIce hold cold air conditioner technology belong to new technology still in our country , it heavy advantage that the electricity moves the peak and operates the expenses sparingly most. In design, is it ice mode adopt some (weight ) hold mode of icing , is it ice refrigeration to be plane utilization ratio high to hold partly to hold, hold cold capacity little , refrigeration plane capacity 30%-45% little than routine air conditioner equipment, one economic effective operational mode.Hold the implementation of the technology of the cold air conditioner in order to cooperate with the ice , has used intelligent technology, having adopted the computer to control in holding and icing the air conditioner system, the main task has five following respects:(1) According to the demand for user's cold load , according to the characteristic of the structure of the electric rate , set up the ice and hold the best operation way of the cold system automatically, reduce the operation expenses of the whole system;(2) Fully utilize and hold the capacity of the cold device, should try one's best to use up all the cold quantity heldbasically on the same day;(3) Automatic operation state of detection system, ensure ice hold cold system capital equipment normal , safe operation;(4) Automatic record parameter that system operate, display system operate flow chart and type systematic operation parameter report form;(5) Predict future cooling load, confirm the future optimization operation scheme.Ice hold cold air conditioner system test run for some time, indicate control system to be steady , reliable , easy to operate, the system operates the energy-conserving result remarkably.6, the compounding type keeps in the wall warm and insulates against heat To the area of Hangzhou , want heating , climate characteristic of lowering the temperature in summer in winter, is it protect building this structural design person who compound is it insulate against heat the wall to keep warm to enclose specially, namely: Fit up , keep warm , insulate against heat the three not to equal to the body , realize building energy-conservation better.Person who compound is it insulate against heat wall to combine elevation model characteristic , design aluminium board elevation renovation material to keep warm, its structure is: Fill out and build hollow brick in the frame structure, do to hang the American Fluorine carbon coating inferior mere aluminium board outside the hollow brick wall.Aluminium board spoke hot to have high-efficient adiabatic performance to the sun, under the same hot function of solar radiation, because the nature , color of the surfacematerial are different from coarse degree, whether can absorb heat have great difference very , between surface and solar radiation hot absorption system (α ) and material radiation system (Cλ ) is it say to come beyond the difference this. Adopt α and Cλ value little surface material have remarkable result , board α、Cλ value little aluminium have, its α =0.26, Cλ =0.4, light gray face brick α =0.56, Cλ =4.3.Aluminium board for is it hang with having layer under air by hollow brick to do, because aluminium board is it have better radiation transfer to hot terms to put in layer among the atmosphere and air, this structure is playing high-efficient adiabatic function on indoor heating too in winter, so, no matter or can well realize building energy-conservation in winter in summer.7, popularize the technology of sectional electricity distribution roomConsider one layer paves Taxi " gold " value , the total distribution of the building locates the east, set up voltage transformer and low-voltage distribution in the same room in first try in the design, make up sectional electricity distribution room , save transformer substation area greatly , adopt layer assign up and down, mixing the switchyard system entirely after building up and putting into operation, the function is clear , the overall arrangement compactness is rational , the systematic dispatcher is flexible . The technology have to go to to use and already become the model extensively of the design afterwards.ConclusionThe whole mode designed of the building synthetically can raise the adaptability of the building , it will be theinevitable trend , environmental consciousness and awareness of saving energy especially after strengthening are even more important. Developing with the economy , science and technology constantly in our country, more advanced technology and scientific and technical result will be applied to the building , believe firmly that in the near future , more outstanding building global design will appear on the building stage of our country. We will be summarizing, progressing constantly constantly, this is that history gives the great responsibility of architect and engineer.汉语翻译建筑结构整体设计-建筑创作和综合技术21世纪将是多种学科技术并存的时代，它必将形成推动建筑发展的巨大动力，建筑结构整体设计也就越来越重要，建筑师必须把握时机，充分发挥建筑师的主导作用，主持好各项建筑工程设计。
土木工程专业毕业设计外文文献及翻译
英文原文:Rehabilitation of rectangular simply supported RC beams with shear deficiencies using CFRP compositesAhmed Khalifa a，＊，Antonio Nanni ba Department of Structural Engineering，University of Alexandria，Alexandria 21544, Egyptb Department of Civil Engineering，University of Missouri at Rolla，Rolla，MO 65409，USAReceived 28 April 1999；received in revised form 30 October 2001; accepted 10 January 2002AbstractThe present study examines the shear performance and modes of failure of rectangular simply supported reinforced concrete(RC) beams designed with shear deficiencies. These members were strengthened with externally bonded carbon fiber reinforced polymer （CFRP) sheets and evaluated in the laboratory。
The experimental program consisted of twelve full-scale RC beams tested to fail in shear. The variables investigated within this programincluded steel stirrups，and the shear span-to—effective depth ratio，as well as amount and distribution of CFRP。
土木工程-毕业设计-论文-外文翻译-中英文对照
英文原文：Concrete structure reinforcement designSheyanb oⅠWangchenji aⅡⅠFoundation Engineering Co., Ltd. Heilongjiang DongyuⅡHeilongjiang Province, East Building Foundation Engineering Co., Ltd. CoalAbstract：structure in the long-term natural environment and under the use environment's function, its function is weaken inevitably gradually, our structural engineering's duty not just must finish the building earlier period the project work, but must be able the science appraisal structure damage objective law and the degree, and adopts the effective method guarantee structure the security use, that the structure reinforcement will become an important work. What may foresee will be the 21st century, the human building also by the concrete structure, the steel structure, the bricking-up structure and so on primarily, the present stage I will think us in the structure reinforcement this aspect research should also take this as the main breakthrough direction.Key word：Concrete structure reinforcement bricking-up structure reinforcement steel structure reinforcement1 Concrete structure reinforcementConcrete structure's reinforcement divides into the direct reinforcement and reinforces two kinds indirectly, when the design may act according to the actual condition and the operation requirements choice being suitable method and the necessary technology.1.1the direct reinforcement's general method1）Enlarges the section reinforcement lawAdds the concretes cast-in-place level in the reinforced concrete member in bending compression zone, may increase the section effective height, the expansion cross sectional area, thus enhances the component right section anti-curved, the oblique section anti-cuts ability and the section rigidity, plays the reinforcement reinforcement the role.In the suitable muscle scope, the concretes change curved the component right section supporting capacity increase along with the area of reinforcement and the intensity enhance. In the original component right section ratio of reinforcement not too high situation, increases the main reinforcement area to be possible to propose the plateau component right section anti-curved supporting capacity effectively. Is pulled in the section the area to add the cast-in-place concrete jacket to increase the component section, through new Canada partial and original component joint work, but enhances the component supporting capacity effectively, improvement normal operational performance.Enlarges the section reinforcement law construction craft simply, compatible, and has the mature design and the construction experience; Is suitable in Liang, the board, the column, the wall and the general structure concretes reinforcement; But scene construction's wet operating time is long, to produces has certain influence with the life, and after reinforcing the building clearance has certain reduction.2) Replacement concretes reinforcement lawThis law's merit with enlarges the method of sections to be close, and after reinforcing, does not affect building's clearance, but similar existence construction wet operating time long shortcoming; Is suitable somewhat low or has concretes carrier's and so on serious defect Liang, column in the compression zone concretes intensity reinforcement.3) the caking outsourcing section reinforcement lawOutside the Baotou Steel Factory reinforcement is wraps in the section or the steel plate is reinforced component's outside, outside the Baotou Steel Factory reinforces reinforced concrete Liang to use the wet outsourcing law generally, namely uses the epoxy resinification to be in the milk and so on methods with to reinforce the section the construction commission to cake a whole, after the reinforcement component, because is pulled with the compressed steel cross sectional area large scale enhancement, therefore right section supporting capacity and section rigidity large scale enhancement.This law also said that the wet outside Baotou Steel Factory reinforcement law, the stress is reliable, the construction is simple, the scene work load is small, but is big with the steel quantity, and uses in above not suitably 600C in the non-protection's situation the high temperature place; Is suitable does not allow in the use obviously to increase the original component section size, but requests to sharpen its bearing capacity large scale the concrete structure reinforcement.4) Sticks the steel reinforcement lawOutside the reinforced concrete member in bending sticks the steel reinforcement is (right section is pulled in the component supporting capacity insufficient sector area, right section compression zone or oblique section) the superficial glue steel plate, like this may enhance is reinforced component's supporting capacity, and constructs conveniently.This law construction is fast, the scene not wet work or only has the plastering and so on few wet works, to produces is small with the life influence, and after reinforcing, is not remarkable to the original structure outward appearance and the original clearance affects, but the reinforcement effect is decided to a great extent by the gummy craft and the operational level; Is suitable in the withstanding static function, and is in the normal humidity environment to bend or the tension member reinforcement.5) Glue fibre reinforcement plastic reinforcement lawOutside pastes the textile fiber reinforcement is pastes with the cementing material the fibre reinforcement compound materials in is reinforced the component to pull the region, causes it with to reinforce the section joint work, achieves sharpens the component bearing capacity the goal. Besides has glues the steel plate similar merit, but also has anticorrosive muddy, bears moistly, does not increase the self-weight of structure nearly, durably, the maintenance cost low status merit, but needs special fire protection processing, is suitable in each kind of stress nature concrete structure component and the general construction.This law's good and bad points with enlarge the method of sections to be close; Is suitable reinforcement which is insufficient in the concrete structure component oblique section supporting capacity, or must exert the crosswise binding force to the compressional member the situation.6) Reeling lawThis law's good and bad points with enlarge the method of sections to be close; Is suitable reinforcement which is insufficient in the concrete structure component oblique section supporting capacity, or must exert the crosswise binding force to the compressional member the situation.7) Fang bolt anchor lawThis law is suitable in the concretes intensity rank is the C20~C60 concretes load-bearing member transformation, the reinforcement; It is not suitable for already the above structure which and the light quality structure makes decent seriously. 1.2The indirect reinforcement's general method1)Pre-stressed reinforcement law(1)Thepre-stressed horizontal tension bar reinforces concretes member in bending,because the pre-stressed and increases the exterior load the combined action, in the tension bar has the axial tension, this strength eccentric transmits on the component through the pole end anchor (, when tension bar and Liang board bottom surface close fitting, tension bar can look for tune together with component, this fashion has partial pressures to transmit directly for component bottom surface), has the eccentric compression function in the component, this function has overcome the bending moment which outside the part the load produces, reduced outside the load effect, thus sharpened component's anti-curved ability. At the same time, because the tension bar passes to component's pressure function, the component crack development can alleviate, the control, the oblique section anti-to cut the supporting capacity also along with it enhancement.As a result of the horizontal lifting stem's function, the original component's section stress characteristic by received bends turned the eccentric compression, therefore, after the reinforcement, component's supporting capacity was mainly decided in bends under the condition the original component's supporting capacity 。
土木工程毕业论文中英文翻译
外文翻译班级：xxx学号：xxx姓名：xxx一、外文原文：Structural Systems to resist lateral loadsCommonly Used structural SystemsWith loads measured in tens of thousands kips, there is little room in the design of high-rise buildings for excessively complex thoughts. Indeed, the better high-rise buildings carry the universal traits of simplicity of thought and clarity of expression.It does not follow that there is no room for grand thoughts. Indeed, it is with such grand thoughts that the new family of high-rise buildings has evolved. Perhaps more important, the new concepts of but a few years ago have become commonplace in today’ s technology.Omitting some concepts that are related strictly to the materials of construction, the most commonly used structural systems used in high-rise buildings can be categorized as follows:1.Moment-resisting frames.2.Braced frames, including eccentrically braced frames.3.Shear walls, including steel plate shear walls.4.Tube-in-tube structures.5.Core-interactive structures.6.Cellular or bundled-tube systems.Particularly with the recent trend toward more complex forms, but in response also to the need for increased stiffness to resist the forces from wind and earthquake, most high-rise buildings have structural systems built up of combinations of frames, braced bents, shear walls, and related systems. Further, for the taller buildings, the majorities are composed of interactive elements in three-dimensional arrays.The method of combining these elements is the very essence of the design process for high-rise buildings. These combinations need evolve in response to environmental, functional, and cost considerations so as to provide efficient structures that provoke the architectural development to new heights. This is not to say that imaginative structural design can create great architecture. To the contrary, many examples of fine architecture have been created with only moderate support from thestructural engineer, while only fine structure, not great architecture, can be developed without the genius and the leadership of a talented architect. In any event, the best of both is needed to formulate a truly extraordinary design of a high-rise building.While comprehensive discussions of these seven systems are generally available in the literature, further discussion is warranted here .The essence of the design process is distributed throughout the discussion.Moment-Resisting FramesPerhaps the most commonly used system in low-to medium-rise buildings, the moment-resisting frame, is characterized by linear horizontal and vertical members connected essentially rigidly at their joints. Such frames are used as a stand-alone system or in combination with other systems so as to provide the needed resistance to horizontal loads. In the taller of high-rise buildings, the system is likely to be found inappropriate for a stand-alone system, this because of the difficulty in mobilizing sufficient stiffness under lateral forces.Analysis can be accomplished by STRESS, STRUDL, or a host of other appropriate computer programs; analysis by the so-called portal method of the cantilever method has no place in today’s technology.Because of the intrinsic flexibility of the column/girder intersection, and because preliminary designs should aim to highlight weaknesses of systems, it is not unusual to use center-to-center dimensions for the frame in the preliminary analysis. Of course, in the latter phases of design, a realistic appraisal in-joint deformation is essential.Braced Frame sThe braced frame, intrinsically stiffer than the moment –resisting frame, finds also greater application to higher-rise buildings. The system is characterized by linear horizontal, vertical, and diagonal members, connected simply or rigidly at their joints. It is used commonly in conjunction with other systems for taller buildings and as a stand-alone system in low-to medium-rise buildings.While the use of structural steel in braced frames is common, concrete frames are more likely to be of the larger-scale variety.Of special interest in areas of high seismicity is the use of the eccentric braced frame.Again, analysis can be by STRESS, STRUDL, or any one of a series of two –or three dimensional analysis computer programs. And again, center-to-center dimensions are used commonly in the preliminary analysis.Shear wallsThe shear wall is yet another step forward along a progression of ever-stiffer structural systems. The system is characterized by relatively thin, generally (but not always) concrete elements that provide both structural strength and separation between building functions.In high-rise buildings, shear wall systems tend to have a relatively high aspect ratio, that is, their height tends to be large compared to their width. Lacking tension in the foundation system, any structural element is limited in its ability to resist overturning moment by the width of the system and by the gravity load supported by the element. Limited to a narrowoverturning, One obvious use of the system, which does have the needed width, is in the exterior walls of building, where the requirement for windows is kept small.Structural steel shear walls, generally stiffened against buckling by a concrete overlay, have found application where shear loads are high. The system, intrinsically more economical than steel bracing, is particularly effective in carrying shear loads down through the taller floors in the areas immediately above grade. The system has the further advantage of having high ductility a feature of particular importance in areas of high seismicity.The analysis of shear wall systems is made complex because of the inevitable presence of large openings through these walls. Preliminary analysis can be by truss-analogy, by the finite element method, or by making use of a proprietary computer program designed to consider the interaction, or coupling, of shear walls.Framed or Braced TubesThe concept of the framed or braced or braced tube erupted into the technology with the IBM Building in Pittsburgh, but was followed immediately with the twin 110-story towers of the World Trade Center, New York and a number of other buildings .The system is characterized by three –dimensional frames, braced frames, or shear walls, forming a closed surface more or less cylindrical in nature, but of nearly any plan configuration. Because those columns that resist lateral forces are placed as far as possible from the cancroids of the system, the overall moment of inertia is increased and stiffness is very high.The analysis of tubular structures is done using three-dimensional concepts, or by two- dimensional analogy, where possible, whichever method is used, it must be capable of accounting for the effects of shear lag.The presence of shear lag, detected first in aircraft structures, is a serious limitation in the stiffness of framed tubes. The concept has limited recent applications of framed tubes to the shear of 60 stories. Designers have developed various techniques for reducing the effects of shear lag, most noticeably the use of belt trusses. This system finds application in buildings perhaps 40stories and higher. However, except for possible aesthetic considerations, belt trusses interfere with nearly every building function associated with the outside wall; the trusses are placed often at mechanical floors, mush to the disapproval of the designers of the mechanical systems. Nevertheless, as a cost-effective structural system, the belt truss works well and will likely find continued approval from designers. Numerous studies have sought to optimize the location of these trusses, with the optimum location very dependent on the number of trusses provided. Experience would indicate, however, that the location of these trusses is provided by the optimization of mechanical systems and by aesthetic considerations, as the economics of the structural system is not highly sensitive to belt truss location.Tube-in-Tube StructuresThe tubular framing system mobilizes every column in the exterior wall in resisting over-turning and shearing forces. The term‘tube-in-tube’is largely self-explanatory in that a second ring of columns, the ring surrounding the central service core of the building, is used as an inner framed or braced tube. The purpose of the second tube is to increase resistance to overturning and to increase lateral stiffness. The tubes need not be of the same character; that is, one tube could be framed, while the other could be braced.In considering this system, is important to understand clearly the difference between the shear and the flexural components of deflection, the terms being taken from beam analogy. In a framed tube, the shear component of deflection is associated with the bending deformation of columns and girders (i.e, the webs of the framed tube) while the flexural component is associated with the axial shortening and lengthening of columns (i.e, the flanges of the framed tube). In a braced tube, the shear component of deflection is associated with the axial deformation of diagonals while the flexural component of deflection is associated with the axial shortening and lengthening of columns.Following beam analogy, if plane surfaces remain plane (i.e, the floor slabs),then axial stresses in the columns of the outer tube, being farther form the neutral axis, will be substantially larger than the axial stresses in the inner tube. However, in the tube-in-tube design, when optimized, the axial stresses in the inner ring of columns may be as high, or even higher, than the axial stresses in the outer ring. This seeming anomaly is associated with differences in the shearing component of stiffness between the two systems. This is easiest to under-stand where the inner tube is conceived as a braced (i.e, shear-stiff) tube while the outer tube is conceived as a framed (i.e, shear-flexible) tube.Core Interactive StructuresCore interactive structures are a special case of a tube-in-tube wherein the two tubes are coupled together with some form of three-dimensional space frame. Indeed, the system is used often wherein the shear stiffness of the outer tube is zero. The United States Steel Building, Pittsburgh, illustrates the system very well. Here, the inner tube is a braced frame, the outer tube has no shear stiffness, and the two systems are coupled if they were considered as systems passing in a straight line from the “hat” structure. Note that the exterior columns would be improperly modeled if they were considered as systems passing in a straight line from the “hat” to the foundations; these columns are perhaps 15% sti ffer as they follow the elastic curve of the braced core. Note also that the axial forces associated with the lateral forces in the inner columns change from tension to compression over the height of the tube, with the inflection point at about 5/8 of the height of the tube. The outer columns, of course, carry the same axial force under lateral load for the full height of the columns because the columns because the shear stiffness of the system is close to zero.The space structures of outrigger girders or trusses, that connect the inner tube to the outer tube, are located often at several levels in the building. The AT&T headquarters is an example of an astonishing array of interactive elements:1.The structural system is 94 ft (28.6m) wide, 196ft(59.7m) long, and 601ft (183.3m) high.2.Two inner tubes are provided, each 31ft(9.4m) by 40 ft (12.2m), centered 90 ft (27.4m) apart in the long direction of thebuilding.3.The inner tubes are braced in the short direction, but with zero shear stiffness in the long direction.4. A single outer tube is supplied, which encircles the building perimeter.5.The outer tube is a moment-resisting frame, but with zero shear stiffness for the center50ft (15.2m) of each of the longsides.6. A space-truss hat structure is provided at the top of the building.7. A similar space truss is located near the bottom of the building8.The entire assembly is laterally supported at the base on twin steel-plate tubes, because the shear stiffness of the outertube goes to zero at the base of the building.Cellular structuresA classic example of a cellular structure is the Sears Tower, Chicago, a bundled tube structure of nine separate tubes. While the Sears Tower contains nine nearly identical tubes, the basic structural system has special application for buildings of irregular shape, as the several tubes need not be similar in plan shape, It is not uncommon that some of the individual tubes one of the strengths and one of the weaknesses of the system.This special weakness of this system, particularly in framed tubes, has to do with the concept of differential column shortening. The shortening of a column under load is given by the expression△=ΣfL/EFor buildings of 12 ft (3.66m) floor-to-floor distances and an average compressive stress of 15 ksi (138MPa), the shortening of a column under load is 15 (12)(12)/29,000 or 0.074in (1.9mm) per story. At 50 stories, the column will have shortened to 3.7 in. (94mm) less than its unstressed length. Where one cell of a bundled tube system is, say, 50stories high and an adjacent cell is, say, 100stories high, those columns near the boundary between .the two systems need to have this differential deflection reconciled.Major structural work has been found to be needed at such locations. In at least one building, the Rialto Project,Melbourne, the structural engineer found it necessary to vertically pre-stress the lower height columns so as to reconcile the differential deflections of columns in close proximity with the post-tensioning of the shorter column simulating the weight to be added on to adjacent, higher columns.二、原文翻译：抗侧向荷载的结构体系常用的结构体系若已测出荷载量达数千万磅重，那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。
土木工程毕业设计外文翻译最终中英文
7 Rigid-Frame StructuresA rigid-frame high-rise structure typically comprises parallel or orthogonally arranged bents consisting of columns and girders with moment resistant joints. Resistance to horizontal loading is provided by the bending resistance of the columns, girders, and joints. The continuity of the frame also contributes to resisting gravity loading, by reducing the moments in the girders.The advantages of a rigid frame are the simplicity and convenience of its rectangular form.Its unobstructed arrangement, clear of bracing members and structural walls, allows freedom internally for the layout and externally for the fenestration. Rigid frames are considered economical for buildings of up to' about25 stories, above which their drift resistance is costly to control. If, however,a rigid frame is combined with shear walls or cores, the resulting structure is very much stiffer so that its height potential may extend up to 50 stories or more. A flat plate structure is very similar to a rigid frame, but with slabs replacing the girders As with a rigid frame, horizontal and vertical loadings are resisted in a flat plate structure by the flexural continuity between the vertical and horizontal components.As highly redundant structures, rigid frames are designed initially on the basis of approximate analyses, after which more rigorous analyses and checks can be made. The procedure may typically include the following stages:1. Estimation of gravity load forces in girders and columns by approximate method.2. Preliminary estimate of member sizes based on gravity load forces witharbitrary increase in sizes to allow for horizontal loading.3. Approximate allocation of horizontal loading to bents and preliminary analysisof member forces in bents.4. Check on drift and adjustment of member sizes if necessary.5. Check on strength of members for worst combination of gravity and horizontalloading, and adjustment of member sizes if necessary.6. Computer analysis of total structure for more accurate check on memberstrengths and drift, with further adjustment of sizes where required. This stage may include the second-order P-Delta effects of gravity loading on the member forces and drift..7. Detailed design of members and connections.This chapter considers methods of analysis for the deflections and forces for both gravity and horizontal loading. The methods are included in roughly the order of the design procedure, with approximate methods initially and computer techniques later. Stability analyses of rigid frames are discussed in Chapter 16.7.1 RIGID FRAME BEHAVIORThe horizontal stiffness of a rigid frame is governed mainly by the bending resistance of the girders, the columns, and their connections, and, in a tall frame, by the axial rigidity of the columns. The accumulated horizontal shear above any story of a rigid frame is resisted by shear in the columns of that story (Fig. 7.1). The shear causes the story-height columns to bend in double curvature with points of contraflexure at approximately mid-story-height levels. The moments applied to a joint from the columns above and below are resisted by the attached girders, which also bend in double curvature, with points of contraflexure at approximately mid-span. These deformations of the columns and girders allow racking of the frame and horizontal deflection in each story. The overall deflected shape of a rigid frame structure due to racking has a shear configuration with concavity upwind, a maximum inclination near the base, and a minimum inclination at the top, as shown in Fig.7.1.The overall moment of the external horizontal load is resisted in each story level by the couple resulting from the axial tensile and compressive forces in the columns on opposite sides of the structure (Fig. 7.2). The extension and shortening of the columns cause overall bending and associated horizontal displacements of the structure. Because of the cumulative rotation up the height, the story drift dueto overall bending increases with height, while that due to racking tends to decrease. Consequently the contribution to story drift from overall bending may, in. the uppermost stories, exceed that from racking. The contribution of overall bending to the total drift, however, will usually not exceed 10% of that of racking, except in very tall, slender,, rigid frames. Therefore the overall deflected shape of a high-rise rigid frame usually has a shear configuration.The response of a rigid frame to gravity loading differs from a simply connected frame in the continuous behavior of the girders. Negative moments are induced adjacent to the columns, and positive moments of usually lesser magnitude occur in the mid-span regions. The continuity also causes the maximum girder moments to be sensitive to the pattern of live loading. This must be considered when estimating the worst moment conditions. For example, the gravity load maximum hogging moment adjacent to an edge column occurs when live load acts only on the edge span and alternate other spans, as for A in Fig. 7.3a. The maximum hogging moments adjacent to an interior column are caused, however, when live load acts only on the spans adjacent to the column, as for B in Fig. 7.3b. The maximum mid-span sagging moment occurs when live load acts on the span under consideration, and alternate other spans, as for spans AB and CD in Fig. 7.3a.The dependence of a rigid frame on the moment capacity of the columns for resisting horizontal loading usually causes the columns of a rigid frame to be larger than those of the corresponding fully braced simply connected frame. On the other hand, while girders in braced frames are designed for their mid-span sagging moment, girders in rigid frames are designed for the end-of-span resultant hogging moments, which may be of lesser value. Consequently, girders in a rigid frame may be smaller than in the corresponding braced frame. Such reductions in size allow economy through the lower cost of the girders and possible reductions in story heights. These benefits may be offset, however, by the higher cost of the more complex rigid connections.7.2 APPROXIMATE DETERMINATION OF MEMBER FORCES CAUSED BY GRAVITY LOADSIMGA rigid frame is a highly redundant structure; consequently, an accurate analysis can be made only after the member sizes are assigned. Initially, therefore, member sizes are decided on the basis of approximate forces estimated either by conservative formulas or by simplified methods of analysis that are independent of member properties. Two approaches for estimating girder forces due to gravity loading are given here.7.2.1 Girder Forces—Code Recommended ValuesIn rigid frames with two or more spans in which the longer of any two adjacent spans does not exceed the shorter by more than 20 %, and where the uniformly distributed design live load does not exceed three times the dead load, the girder moment and shears may be estimated from Table 7.1. This summarizes the recommendations given in the Uniform Building Code [7.1]. In other cases a conventional moment distribution or two-cycle moment distribution analysis should be made for a line of girders at a floor level.7.2.2 Two-Cycle Moment Distribution [7.2].This is a concise form of moment distribution for estimating girder moments in a continuous multibay span. It is more accurate than the formulas in Table 7.1, especially for cases of unequal spans and unequal loading in different spans.The following is assumed for the analysis:1. A counterclockwise restraining moment on the end of a girder is positive anda clockwise moment is negative.2. The ends of the columns at the floors above and below the considered girder are fixed.3. In the absence of known member sizes, distribution factors at each joint aretaken equal to 1 /n, where n is the number of members framing into the joint in the plane of the frame.Two-Cycle Moment Distribution—Worked Example. The method is demonstrated by a worked example. In Fig, 7.4, a four-span girder AE from a rigid-frame bent is shown with its loading. The fixed-end moments in each span are calculated for dead loading and total loading using the formulas given in Fig, 7.5. The moments are summarized in Table 7.2.The purpose of the moment distribution is to estimate for each support the maximum girder moments that can occur as a result of dead loading and pattern live loading.A different load combination must be considered for the maximum moment at each support, and a distribution made for each combination.The five distributions are presented separately in Table 7.3, and in a combined form in Table 7.4. Distributions a in Table 7.3 are for the exterior supports A andE. For the maximum hogging moment at A, total loading is applied to span AB with dead loading only on BC. The fixed-end moments are written in rows 1 and 2. In this distribution only .the resulting moment at A is of interest. For the first cycle, joint B is balanced with a correcting moment of- (-867 + 315)/4 = - U/4 assigned to M BA where U is the unbalanced moment. This is not recorded, but half of it, ( - U/4)/2, is carried over to M AB. This is recorded in row 3 and then added to the fixed-end moment and the result recorded in row 4.The second cycle involves the release and balance of joint A. The unbalanced moment of 936 is balanced by adding-U/3 = -936/3 = -312 to M BA (row 5), implicitly adding the same moment to the two column ends at A. This completes the second cycle of the distribution. The resulting maximum moment at A is then given by the addition of rows 4 and 5, 936 - 312 = 624. The distribution for the maximum moment at E follows a similar procedure.Distribution b in Table 7.3 is for the maximum moment at B. The most severe loading pattern for this is with total loading on spans AB and BC and dead load only on CD. The operations are similar to those in Distribution a, except that the T first cycle involves balancing the two adjacent joints A and C while recording only their carryover moments to B. In the second cycle, B is balanced by adding - (-1012 + 782)/4 = 58 to each side of B. The addition of rows 4 and 5 then gives the maximum hogging moments at B. Distributions c and d, for the moments at joints C and D, follow patterns similar to Distribution b.The complete set of operations can be combined as in Table 7.4 by initially recording at each joint the fixed-end moments for both dead and total loading. Then the joint, or joints, adjacent to the one under consideration are balanced for the appropriate combination of loading, and carryover moments assigned .to the considered joint and recorded. The joint is then balanced to complete the distribution for that support.Maximum Mid-Span Moments. The most severe loading condition for a maximum mid-span sagging moment is when the considered span and alternate other spans and total loading. A concise method of obtaining these values may be included in the combined two-cycle distribution, as shown in Table 7.5. Adopting the convention that sagging moments at mid-span are positive, a mid-span total; loading moment is calculated for the fixed-end condition of each span and entered in the mid-span column of row 2. These mid-span moments must now be corrected to allow for rotation of the joints. This is achieved by multiplying the carryover moment, row 3, at the left-hand end of the span by (1 + 0.5 D.F. )/2, and the carryover moment at the right-hand end by -(1 + 0.5 D.F.)/2, where D.F. is the appropriate distribution factor, and recording the results in the middle column. For example, the carryover to the mid-span of AB from A = [(1 + 0.5/3)/2] x 69 = 40 and from B = -[(1+ 0.5/4)/2] x (-145) = 82. These correction moments are then added to the fixed-end mid-span moment to give the maximum mid-span sagging moment, that is, 733 + 40 + 82 = 855.7.2.3 Column ForcesThe gravity load axial force in a column is estimated from the accumulated tributary dead and live floor loading above that level, with reductions in live loading as permitted by the local Code of Practice. The gravity load maximum column moment is estimated by taking the maximum difference of the end moments in the connected girders and allocating it equally between the column ends just above and below the joint. To this should be added any unbalanced moment due to eccentricity of the girderconnections from the centroid of the column, also allocated equally between the column ends above and below the joint.第七章框架结构高层框架结构一般由平行或正交布置的梁柱结构组成，梁柱结构是由带有能承担弯矩作用节点的梁、柱组成。
土木工程毕业论文中英文翻译
外文翻译班级：xxx 学号：xxx 姓名：xxx一、外文原文：Structural Systems to resist lateral loadsCommonly Used structural SystemsWith loads measured in tens of thousands kips, there is little room in the design of high-rise buildings for excessively complex thoughts. Indeed, the better high-rise buildings carry the universal traits of simplicity of thought and clarity of expression.It does not follow that there is no room for grand thoughts. Indeed, it is with such grand thoughts that the new family of high-rise buildings has evolved. Perhaps more important, the new concepts of but a few years ago have become commonplace in today’ s technology.Omitting some concepts that are related strictly to the materials of construction, the most commonly used structural systems used in high-rise buildings can be categorized as follows:1.Moment-resisting frames.2.Braced frames, including eccentrically braced frames.3.Shear walls, including steel plate shear walls.4.Tube-in-tube structures.5.Core-interactive structures.6.Cellular or bundled-tube systems.Particularly with the recent trend toward more complex forms, but in response also to the need for increased stiffness to resist the forces from wind and earthquake, most high-rise buildings have structural systems built up of combinations of frames, braced bents, shear walls, and related systems. Further, for the taller buildings, the majorities are composed of interactive elements in three-dimensional arrays.The method of combining these elements is the very essence of the design process for high-rise buildings. These combinations need evolve in response to environmental, functional, and cost considerations so as to provide efficient structures that provoke the architectural development to new heights. This is not to say that imaginative structural design can create great architecture. To the contrary, many examples of fine architecture have been created with only moderate support from the structural engineer, while only fine structure, not great architecture, can be developedwithout the genius and the leadership of a talented architect. In any event, the best of both is needed to formulate a truly extraordinary design of a high-rise building.While comprehensive discussions of these seven systems are generally available in the literature, further discussion is warranted here .The essence of the design process is distributed throughout the discussion.Moment-Resisting FramesPerhaps the most commonly used system in low-to medium-rise buildings, the moment-resisting frame, is characterized by linear horizontal and vertical members connected essentially rigidly at their joints. Such frames are used as a stand-alone system or in combination with other systems so as to provide the needed resistance to horizontal loads. In the taller of high-rise buildings, the system is likely to be found inappropriate for a stand-alone system, this because of the difficulty in mobilizing sufficient stiffness under lateral forces.Analysis can be accomplished by STRESS, STRUDL, or a host of other appropriate computer programs; analysis by the so-called portal method of the cantilever method has no place in today’s technology.Because of the intrinsic flexibility of the column/girder intersection, and because preliminary designs should aim to highlight weaknesses of systems, it is not unusual to use center-to-center dimensions for the frame in the preliminary analysis. Of course, in the latter phases of design, a realistic appraisal in-joint deformation is essential.Braced Frame sThe braced frame, intrinsically stiffer than the moment –resisting frame, finds also greater application to higher-rise buildings. The system is characterized by linear horizontal, vertical, and diagonal members, connected simply or rigidly at their joints. It is used commonly in conjunction with other systems for taller buildings and as a stand-alone system in low-to medium-rise buildings.While the use of structural steel in braced frames is common, concrete frames are more likely to be of the larger-scale variety.Of special interest in areas of high seismicity is the use of the eccentric braced frame.Again, analysis can be by STRESS, STRUDL, or any one of a series of two –or three dimensional analysis computer programs. And again, center-to-center dimensions are used commonly in the preliminary analysis.Shear wallsThe shear wall is yet another step forward along a progression of ever-stiffer structural systems. The system is characterized by relatively thin, generally (but not always) concrete elements that provide both structural strength and separation between building functions.In high-rise buildings, shear wall systems tend to have a relatively high aspect ratio, that is, their height tends to be large compared to their width. Lacking tension in the foundation system, any structural element is limited in its ability to resist overturning moment by the width of the system and by the gravity load supported by the element. Limited to a narrow overturning, One obvious use of the system, which does have the needed width, is in the exterior walls of building, where the requirement for windows is kept small.Structural steel shear walls, generally stiffened against buckling by a concrete overlay, have found application where shear loads are high. The system, intrinsically more economical than steel bracing, is particularly effective in carrying shear loads down through the taller floors in the areas immediately above grade. The system has the further advantage of having high ductility a feature of particular importance in areas of high seismicity.The analysis of shear wall systems is made complex because of the inevitable presence of large openings through these walls. Preliminary analysis can be by truss-analogy, by the finite element method, or by making use of a proprietary computer program designed to consider the interaction, or coupling, of shear walls.Framed or Braced TubesThe concept of the framed or braced or braced tube erupted into the technology with the IBM Building in Pittsburgh, but was followed immediately with the twin 110-story towers of the World Trade Center, New York and a number of other buildings .The system is characterized by three –dimensional frames, braced frames, or shear walls, forming a closed surface more or less cylindrical in nature, but of nearly any plan configuration. Because those columns that resistlateral forces are placed as far as possible from the cancroids of the system, the overall moment of inertia is increased and stiffness is very high.The analysis of tubular structures is done using three-dimensional concepts, or by two- dimensional analogy, where possible, whichever method is used, it must be capable of accounting for the effects of shear lag.The presence of shear lag, detected first in aircraft structures, is a serious limitation in the stiffness of framed tubes. The concept has limited recent applications of framed tubes to the shear of 60 stories. Designers have developed various techniques for reducing the effects of shear lag, most noticeably the use of belt trusses. This system finds application in buildings perhaps 40stories and higher. However, except for possible aesthetic considerations, belt trusses interfere with nearly every building function associated with the outside wall; the trusses are placed often at mechanical floors, mush to the disapproval of the designers of the mechanical systems. Nevertheless, as a cost-effective structural system, the belt truss works well and will likely find continued approval from designers. Numerous studies have sought to optimize the location of these trusses, with the optimum location very dependent on the number of trusses provided. Experience would indicate, however, that the location of these trusses is provided by the optimization of mechanical systems and by aesthetic considerations, as the economics of the structural system is not highly sensitive to belt truss location.Tube-in-Tube StructuresThe tubular framing system mobilizes every column in the exterior wall in resisting over-turning and shearing forces. The term‘tube-in-tube’is largely self-explanatory in that a second ring of columns, the ring surrounding the central service core of the building, is used as an inner framed or braced tube. The purpose of the second tube is to increase resistance to over turning and to increase lateral stiffness. The tubes need not be of the same character; that is, one tube could be framed, while the other could be braced.In considering this system, is important to understand clearly the difference between the shear and the flexural components of deflection, the terms being taken from beam analogy. In a framed tube, the shear component of deflection is associated with the bending deformation of columns and girders (i.e, the webs of the framed tube) while the flexural component is associated with the axial shortening and lengthening of columns (i.e, the flanges of the framed tube). In abraced tube, the shear component of deflection is associated with the axial deformation of diagonals while the flexural component of deflection is associated with the axial shortening and lengthening of columns.Following beam analogy, if plane surfaces remain plane (i.e, the floor slabs),then axial stresses in the columns of the outer tube, being farther form the neutral axis, will be substantially larger than the axial stresses in the inner tube. However, in the tube-in-tube design, when optimized, the axial stresses in the inner ring of columns may be as high, or even higher, than the axial stresses in the outer ring. This seeming anomaly is associated with differences in the shearing component of stiffness between the two systems. This is easiest to under-stand where the inner tube is conceived as a braced (i.e, shear-stiff) tube while the outer tube is conceived as a framed (i.e, shear-flexible) tube.Core Interactive StructuresCore interactive structures are a special case of a tube-in-tube wherein the two tubes are coupled together with some form of three-dimensional space frame. Indeed, the system is used often wherein the shear stiffness of the outer tube is zero. The United States Steel Building, Pittsburgh, illustrates the system very well. Here, the inner tube is a braced frame, the outer tube has no shear stiffness, and the two systems are coupled if they were considered as systems passing in a straight line from the “hat” structure. Note that the exterior columns would be improperly modeled if they were considered as systems passing in a straight line from the “hat” to the foundations; these columns are perhaps 15% stiffer as they follow the elastic curve of the braced core. Note also that the axial forces associated with the lateral forces in the inner columns change from tension to compression over the height of the tube, with the inflection point at about 5/8 of the height of the tube. The outer columns, of course, carry the same axial force under lateral load for the full height of the columns because the columns because the shear stiffness of the system is close to zero.The space structures of outrigger girders or trusses, that connect the inner tube to the outer tube, are located often at several levels in the building. The AT&T headquarters is an example of an astonishing array of interactive elements:1.The structural system is 94 ft (28.6m) wide, 196ft(59.7m) long, and 601ft (183.3m) high.2.Two inner tubes are provided, each 31ft(9.4m) by 40 ft (12.2m), centered 90 ft (27.4m)apart in the long direction of the building.3.The inner tubes are braced in the short direction, but with zero shear stiffness in the longdirection.4. A single outer tube is supplied, which encircles the building perimeter.5.The outer tube is a moment-resisting frame, but with zero shear stiffness for the center50ft(15.2m) of each of the long sides.6. A space-truss hat structure is provided at the top of the building.7. A similar space truss is located near the bottom of the building8.The entire assembly is laterally supported at the base on twin steel-plate tubes, because theshear stiffness of the outer tube goes to zero at the base of the building.Cellular structuresA classic example of a cellular structure is the Sears Tower, Chicago, a bundled tube structure of nine separate tubes. While the Sears Tower contains nine nearly identical tubes, the basic structural system has special application for buildings of irregular shape, as the several tubes need not be similar in plan shape, It is not uncommon that some of the individual tubes one of the strengths and one of the weaknesses of the system.This special weakness of this system, particularly in framed tubes, has to do with the concept of differential column shortening. The shortening of a column under load is given by the expression△=ΣfL/EFor buildings of 12 ft (3.66m) floor-to-floor distances and an average compressive stress of 15 ksi (138MPa), the shortening of a column under load is 15 (12)(12)/29,000 or 0.074in (1.9mm) per story. At 50 stories, the column will have shortened to 3.7 in. (94mm) less than its unstressed length. Where one cell of a bundled tube system is, say, 50stories high and an adjacent cell is, say, 100stories high, those columns near the boundary between .the two systems need to have this differential deflection reconciled.Major structural work has been found to be needed at such locations. In at least one building, the Rialto Project, Melbourne, the structural engineer found it necessary to vertically pre-stressthe lower height columns so as to reconcile the differential deflections of columns in close proximity with the post-tensioning of the shorter column simulating the weight to be added on to adjacent, higher columns.二、原文翻译：抗侧向荷载的结构体系常用的结构体系若已测出荷载量达数千万磅重，那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。
(完整版)土木工程毕业设计外文文献翻译
外文文献翻译Reinforced ConcreteConcrete and reinforced concrete are used as building materials in every country. In many, including the United States and Canada, reinforced concrete is a dominant structural material in engineered construction. The universal nature of reinforced concrete construction stems from the wide availability of reinforcing bars and the constituents of concrete, gravel, sand, and cement, the relatively simple skills required in concrete construction, and the economy of reinforced concrete compared to other forms of construction. Concrete and reinforced concrete are used in bridges, buildings of all sorts underground structures, water tanks, television towers, offshore oil exploration and production structures, dams, and even in ships.Reinforced concrete structures may be cast-in-place concrete, constructed in their final location, or they may be precast concrete produced in a factory and erected at the construction site. Concrete structures may be severe and functional in design, or the shape and layout and be whimsical and artistic. Few other building materials off the architect and engineer such versatility and scope.Concrete is strong in compression but weak in tension. As a result, cracks develop whenever loads, or restrained shrinkage of temperature changes, give rise to tensile stresses in excess of the tensile strength of the concrete. In a plain concrete beam, the moments about the neutral axis due to applied loads are resisted by an internal tension-compression couple involving tension in the concrete. Such a beam fails very suddenly and completely when the first crack forms. In a reinforced concrete beam, steel bars are embedded in the concrete in such a way that the tension forces needed for moment equilibrium after the concrete cracks can be developed in the bars.The construction of a reinforced concrete member involves building a from of mold in the shape of the member being built. The form must be strong enough to support both the weight and hydrostatic pressure of the wet concrete, and any forces applied to it by workers, concrete buggies, wind, and so on. The reinforcement is placed in this form and held in placeduring the concreting operation. After the concrete has hardened, the forms are removed. As the forms are removed, props of shores are installed to support the weight of the concrete until it has reached sufficient strength to support the loads by itself.The designer must proportion a concrete member for adequate strength to resist the loads and adequate stiffness to prevent excessive deflections. In beam must be proportioned so that it can be constructed. For example, the reinforcement must be detailed so that it can be assembled in the field, and since the concrete is placed in the form after the reinforcement is in place, the concrete must be able to flow around, between, and past the reinforcement to fill all parts of the form completely.The choice of whether a structure should be built of concrete, steel, masonry, or timber depends on the availability of materials and on a number of value decisions. The choice of structural system is made by the architect of engineer early in the design, based on the following considerations:1. Economy. Frequently, the foremost consideration is the overall const of the structure. This is, of course, a function of the costs of the materials and the labor necessary to erect them. Frequently, however, the overall cost is affected as much or more by the overall construction time since the contractor and owner must borrow or otherwise allocate money to carry out the construction and will not receive a return on this investment until the building is ready for occupancy. In a typical large apartment of commercial project, the cost of construction financing will be a significant fraction of the total cost. As a result, financial savings due to rapid construction may more than offset increased material costs. For this reason, any measures the designer can take to standardize the design and forming will generally pay off in reduced overall costs.In many cases the long-term economy of the structure may be more important than the first cost. As a result, maintenance and durability are important consideration.2. Suitability of material for architectural and structural function.A reinforced concrete system frequently allows the designer to combine the architectural and structural functions. Concrete has the advantage that it is placed in a plastic condition and is given the desired shapeand texture by means of the forms and the finishing techniques. This allows such elements ad flat plates or other types of slabs to serve as load-bearing elements while providing the finished floor and / or ceiling surfaces. Similarly, reinforced concrete walls can provide architecturally attractive surfaces in addition to having the ability to resist gravity, wind, or seismic loads. Finally, the choice of size of shape is governed by the designer and not by the availability of standard manufactured members.3. Fire resistance. The structure in a building must withstand the effects of a fire and remain standing while the building is evacuated and the fire is extinguished. A concrete building inherently has a 1- to 3-hour fire rating without special fireproofing or other details. Structural steel or timber buildings must be fireproofed to attain similar fire ratings.4. Low maintenance.Concrete members inherently require less maintenance than do structural steel or timber members. This is particularly true if dense, air-entrained concrete has been used for surfaces exposed to the atmosphere, and if care has been taken in the design to provide adequate drainage off and away from the structure. Special precautions must be taken for concrete exposed to salts such as deicing chemicals.5. Availability of materials. Sand, gravel, cement, and concrete mixing facilities are very widely available, and reinforcing steel can be transported to most job sites more easily than can structural steel. As a result, reinforced concrete is frequently used in remote areas.On the other hand, there are a number of factors that may cause one to select a material other than reinforced concrete. These include:1. Low tensile strength.The tensile strength concrete is much lower than its compressive strength ( about 1/10 ), and hence concrete is subject to cracking. In structural uses this is overcome by using reinforcement to carry tensile forces and limit crack widths to within acceptable values. Unless care is taken in design and construction, however, these cracks may be unsightly or may allow penetration of water. When this occurs, water or chemicals such as road deicing salts may cause deterioration or staining of the concrete. Special design details are required in such cases. In the case of water-retaining structures, special details and /of prestressing are required to prevent leakage.2. Forms and shoring. The construction of a cast-in-place structure involves three steps not encountered in the construction of steel or timber structures. These are ( a ) the construction of the forms, ( b ) the removal of these forms, and (c) propping or shoring the new concrete to support its weight until its strength is adequate. Each of these steps involves labor and / or materials, which are not necessary with other forms of construction.3. Relatively low strength per unit of weight for volume.The compressive strength of concrete is roughly 5 to 10% that of steel, while its unit density is roughly 30% that of steel. As a result, a concrete structure requires a larger volume and a greater weight of material than does a comparable steel structure. As a result, long-span structures are often built from steel.4. Time-dependent volume changes. Both concrete and steel undergo-approximately the same amount of thermal expansion and contraction. Because there is less mass of steel to be heated or cooled, and because steel is a better concrete, a steel structure is generally affected by temperature changes to a greater extent than is a concrete structure. On the other hand, concrete undergoes frying shrinkage, which, if restrained, may cause deflections or cracking. Furthermore, deflections will tend to increase with time, possibly doubling, due to creep of the concrete under sustained loads.In almost every branch of civil engineering and architecture extensive use is made of reinforced concrete for structures and foundations. Engineers and architects requires basic knowledge of reinforced concrete design throughout their professional careers. Much of this text is directly concerned with the behavior and proportioning of components that make up typical reinforced concrete structures-beams, columns, and slabs. Once the behavior of these individual elements is understood, the designer will have the background to analyze and design a wide range of complex structures, such as foundations, buildings, and bridges, composed of these elements.Since reinforced concrete is a no homogeneous material that creeps, shrinks, and cracks, its stresses cannot be accurately predicted by the traditional equations derived in a course in strength of materials forhomogeneous elastic materials. Much of reinforced concrete design in therefore empirical, i.e., design equations and design methods are based on experimental and time-proved results instead of being derived exclusively from theoretical formulations.A thorough understanding of the behavior of reinforced concrete will allow the designer to convert an otherwise brittle material into tough ductile structural elements and thereby take advantage of concrete’s desirable characteristics, its high compressive strength, its fire resistance, and its durability.Concrete, a stone like material, is made by mixing cement, water, fine aggregate ( often sand ), coarse aggregate, and frequently other additives ( that modify properties ) into a workable mixture. In its unhardened or plastic state, concrete can be placed in forms to produce a large variety of structural elements. Although the hardened concrete by itself, i.e., without any reinforcement, is strong in compression, it lacks tensile strength and therefore cracks easily. Because unreinforced concrete is brittle, it cannot undergo large deformations under load and fails suddenly-without warning. The addition fo steel reinforcement to the concrete reduces the negative effects of its two principal inherent weaknesses, its susceptibility to cracking and its brittleness. When the reinforcement is strongly bonded to the concrete, a strong, stiff, and ductile construction material is produced. This material, called reinforced concrete, is used extensively to construct foundations, structural frames, storage takes, shell roofs, highways, walls, dams, canals, and innumerable other structures and building products. Two other characteristics of concrete that are present even when concrete is reinforced are shrinkage and creep, but the negative effects of these properties can be mitigated by careful design.A code is a set technical specifications and standards that control important details of design and construction. The purpose of codes it produce structures so that the public will be protected from poor of inadequate and construction.Two types f coeds exist. One type, called a structural code, is originated and controlled by specialists who are concerned with the proper use of a specific material or who are involved with the safe design of a particular class of structures.The second type of code, called a building code, is established to cover construction in a given region, often a city or a state. The objective of a building code is also to protect the public by accounting for the influence of the local environmental conditions on construction. For example, local authorities may specify additional provisions to account for such regional conditions as earthquake, heavy snow, or tornados. National structural codes genrally are incorporated into local building codes.The American Concrete Institute ( ACI ) Building Code covering the design of reinforced concrete buildings. It contains provisions covering all aspects of reinforced concrete manufacture, design, and construction. It includes specifications on quality of materials, details on mixing and placing concrete, design assumptions for the analysis of continuous structures, and equations for proportioning members for design forces.All structures must be proportioned so they will not fail or deform excessively under any possible condition of service. Therefore it is important that an engineer use great care in anticipating all the probable loads to which a structure will be subjected during its lifetime.Although the design of most members is controlled typically by dead and live load acting simultaneously, consideration must also be given to the forces produced by wind, impact, shrinkage, temperature change, creep and support settlements, earthquake, and so forth.The load associated with the weight of the structure itself and its permanent components is called the dead load. The dead load of concrete members, which is substantial, should never be neglected in design computations. The exact magnitude of the dead load is not known accurately until members have been sized. Since some figure for the dead load must be used in computations to size the members, its magnitude must be estimated at first. After a structure has been analyzed, the members sized, and architectural details completed, the dead load can be computed more accurately. If the computed dead load is approximately equal to the initial estimate of its value ( or slightly less ), the design is complete, but if a significant difference exists between the computed and estimated values of dead weight, the computations should be revised using an improved value of dead load. An accurate estimate of dead load is particularly important when spans are long, say over 75 ft ( 22.9 m ),because dead load constitutes a major portion of the design load.Live loads associated with building use are specific items of equipment and occupants in a certain area of a building, building codes specify values of uniform live for which members are to be designed.After the structure has been sized for vertical load, it is checked for wind in combination with dead and live load as specified in the code. Wind loads do not usually control the size of members in building less than 16 to 18 stories, but for tall buildings wind loads become significant and cause large forces to develop in the structures. Under these conditions economy can be achieved only by selecting a structural system that is able to transfer horizontal loads into the ground efficiently.钢筋混凝土在每一个国家，混凝土及钢筋混凝土都被用来作为建筑材料。
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原文题目：Composite Box Girder Bridges
译文题目：混合箱梁桥
院系名称：土木建筑学院专业班级：土木工程F0905 学生姓名：学号： 200948040
指导教师：熊晓莉教师职称：
附件： 1.外文资料翻译译文；2.外文原文。
混合箱梁桥
摘要：在复合箱梁桥的建造过程中，独立梁的梁部分可能会扭曲，因此会增加建造的压力。
这种扭曲和附加的力可能会有效的减少简单的增加和经济的支撑系统。
在阻止扭曲的梁中这样一个系杆的作用从其他规模的模型中获得的结果，简单的工程理论和有限条法分析得到验证。
在梁中相互联系的系杆也被验证。
基于梁对各种各样轴心和偏心荷载的反应所推荐的初步设计也给出了。
14.1 介绍
背景
复合钢筋混凝土箱梁桥在最近几年已经被广泛的使用在中等跨度的桥梁中。
已建成的复合箱梁桥是非常稳定的，就像一个三面的钢筋盒子上面放了一个混凝土平板。
然而，在建造梁的过程中可能会有一个柔性的开口截面可能导致相当大的扭曲产生建造荷载。
开口截面梁的性质并未被很好的掌握，并且有文献报道在桥板安装前和安装时，存在着几何变形和过大的扭曲。
已经完成的结构看起来赏心悦目，由钢箱梁和复合材料制成的混凝土板构成。
在箱梁的设计中与类似的工字型梁和板梁相比更加经济，因为完全复合梁截面有更好的抗弯刚度和并能更好的活荷载水平分布，比起有相似韧性的工字梁结构。
在制造和树立箱梁时也可能会增加费用，比起类似的工字梁，由于风荷载和横向支撑系统。
对于完整的箱型结构来说多种多样的几何横截面是可能的，梁的数量从两个到六个或者更多取决于结构的设计平面几何。
典型的几何横截面在14.2中给出单轴和双轴的布置，浅的和深的无支撑的隔板也列举出来。
通常箱梁的中心线的间距从4.3到6.7米，混凝土板的计算高度为190mm到250mm。
因此，箱梁结构的恒载和活载的比例取决于板的厚度，横截面和间距的选取由设计工程师决定。
建造箱梁的经验表明设计说明并不对设计或者建造工程师提供足够的关于薄樯的箱梁在建造阶段的性能指导。
说明并未清晰的提到建造阶段的支撑需求。
中间隔板或横框可能需要在装配处理和安放混凝土板的时候保持每一根梁的几何横断面的形状。
类似的，隔板或横框在梁中间使用来确保稳定性和限制混凝土浇筑过程中限制水平位移大梁。
经常是总承包商或钢结构制造商负责支撑。
由于在设计中尤为强调的是桥梁的使用状况，所以设计工程师会经常忽略建造时的状况。
在这种情况下，承包商必须使用适宜的程序来支撑箱梁。
支撑的设计可能并不能阻止横向运动，也可能是
过度，造成浪费材料和劳动力以及与业主和承包商之间的冲突。
概述本文介绍了可能存在于薄壁箱梁施工过程中的负荷配置，并验证在典型的扭转半封闭的箱形梁产生的变形和应力。
基于模型试验和原型桥，辅以独立的开口、半封闭的箱形截面和复合部分的分析结果。
对一些支撑系统进行检查，主要包括支撑配置的跨度和一个给定的结构的横截面的功能的类型。
在施工期间，使用这些系统以尽量减少梁的横截面和整个梁的变形，这对设计工程师，制造商和普通承包者来说都更乐于接受。
14.2施工荷载
作为设计的一部分，设计工程师应选择一个符合高速公路的功能要求的横截面几何形状的桥梁结构。
在设计过程的早期阶段桥板相对于箱梁中心线和已经完成箱梁系统的位置已经被确定。
典型的截面几何形状连同各种负载情况下的示意图在两个例子中给出的，即图14,3。
轴心和偏心载荷的混凝土梁已经列出。
对于理想化的轴心加载情况下，板的重量由四个倾斜腹板共同承担。
一旦箱梁所承受的荷载沿中心线，扭曲的剪切中心将不会发生，弯曲和扭转载荷很容易识别。
压力法兰的支撑系统是必须的，以避免由于垂直载荷和水平方向的力的组合作用造成的横向移动或屈曲。
几何设计上的限制，可能会导致混凝土相对于单个梁的纵向中心线偏心（图
14.3）。
例如，设计者可能按照规范采取措施将悬臂梁上边选出部分控制到相邻相邻桥相邻上翼缘之间的距离百分之六十或少于两米。
偏心混凝土板导致荷载分布的不规整，弯曲和扭转载荷的发展，梁的剪切中心旋转产生垂直偏转和水平偏转。
对于轴心和偏心荷载来说，由于垂直荷载的作用约束对剪切中心有限制作用。
还应当提供的支撑约束扭转载荷。
约束扭转荷载很容易被设计成14.2中的系统1或者2.然而，一个同铰支座相连的标准隔横板（图14.2中的系统3）需要特殊设计和详细的链接和隔板构件图以确保有足够的刚度和抗扭刚度。
这后一种用单轴承和名义隔膜的系统不推荐使用。
可以给其他的附载在施工期间产生可预测的扭转效应;这些包括暴露的大梁的风荷载，整理机，和模板。
在每一种情况下，必须提供足够的扭转约束不仅保证了桥梁的整体稳定性的，但也限制单个梁的水平挠曲到可接受的水平。
扭转荷载的计算和因为风荷载，地震荷载产生的位移的计算可以再设计阶段用一些简化的假设来进行。
在施工期间也有其他的扭矩作用。
这些可能包括由总承包商选择的混凝土处理系统，或将桥面混凝土在非对称结构时的影响。
这些荷载的扭曲影响可以通过细致的规范来降低，而且这些相对于上述讨论的那些通常是很小的，
从加拿大三个独立的箱梁桥的设计图纸中总结出来的，弯曲和扭转载荷的总结在图14.4中。
对于设计师来说由混凝土和模板产生的弯矩导致剪心和隔板弯曲形式类似。
混凝土，模板和风力负荷相结合产生的弯曲类似于这些弯矩图。
在图中给出的均匀分布的荷载和均匀分布的弯矩为垂直风荷载值。
值中也给出的偏心率，e / b，其中，e是相对于主梁中心线的偏心的垂直载荷和b是框的平均宽度。
这些偏心率从0.04到0.12不等。
14.3行业通常做法
单个做法
一个不规则的箱梁截面的选择和面积比例由于扭转要遵循以下特点：
（a）扭转开口截面;
（b）半封闭的扭转截面，带有一个靠近凸缘水平的桁架系统;
（c）一个连接梁的顶部法兰的连续板的扭转的封闭截面。
在图14.5中示出的开口和半封闭截面。
扭转封闭截面很少用于复合桥梁结构，因为经济原因和在力作用下薄的封闭板确保稳定的困难。
因而，计算程序经常把封闭的截面作为一个理想化的半封闭截面。
当截面为任何形式的单跨桥受扭时，桥绕着剪心扭转，剪心的位置是所用截面的几何函数。
对于典型的开口截面的箱梁桥来说，剪切中心位大约位于中间部位，在梁底部边缘的下面。
对于具有长细比约200的的一个半封闭截面桁架式支撑系统，剪切中心的位置的稍上方的开口部分。
如果梁是一个封闭的截面，并有两个轴的对称结构，既有垂直腹板和等厚上下翼缘板，剪切中心和几何形心重合。
桥梁很少有这样的几何结构。
对于顶端的平面支撑法兰截面和扭转开口截面，剪切中心和旋转中心位于底部边缘以下。
横截面
在小跨度跨度箱形梁重力和扭转线荷载。
在重力荷载，刚性的部分偏转（纵向弯曲），变形（弯曲变形）。
在扭转载荷作用下，部分刚性旋转（混合扭转）和变形（扭转变形）。
纵向弯曲
当梁承受作用在剪切中心横向载荷，弯曲正应力也随之产生。
关联的剪切应力也可能会发生由于沿着梁的弯矩的变化。
这些可以从平衡考虑来计算。
这种分析是基于的的纳维假设和忽视由于引起的横截面变形位移的应力弯曲产生的剪切应变。
这些变形位移几乎是线性的，在腹板和法兰中受到剪切的影响为抛物线形。
也造成了弯曲正应力的从分配。
这种影响通常是小箱梁，大集中荷载作用下或薄，宽法兰梁除外。
混合扭矩
重力荷载不通过剪切中心时，梁的纵向轴线将会扭转变形。
如果扭转角度的变化比率是恒定的而且弯曲不受限制那么均匀扭转和相关联的剪切应力将会出现。
如果沿着梁的扭矩是变化的或者弯曲被阻止那么非均匀扭转（混合扭转）就会出现，纵向扭转弯曲应力继续增大。
这些应力的变化导致了在横截面弯曲剪应力的产生，这些应力加上圣维南应力来平衡截面中的总弯矩。
在开口箱梁中，扭矩主要由弯曲扭矩来平衡，因为圣维南扭矩的刚度相比较来说刚度比较小。