分析预应力混凝土连续梁毕业论文外文文献翻译及原文
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。
土木工程钢筋混凝土结构中英文对照外文翻译文献
中英文翻译原文：DESIGN OF REINFORCED CONCRETESTRUCTURES1. BASIC CONCERPTS AND CHARACERACTERISTICS OF REINFORCED CONCRETEPlain concrete is formed from hardened mixture of cement, water , fine aggregate , coarse aggregate (crushed stone or gravel ) , air and often other admixtures . The plastic mix is placed and consolidated in the formwork, then cured to accelerate of the chemical hydration of hen cement mix and results in a hardened concrete. It is generally known that concrete has high compressive strength and low resistance to tension. Its tensile strength is approximatelyone-tenth of its compressive strength. Consequently, tensile reinforcement in the tension zone has to be provided to supplement the tensile strength of the reinforced concrete section.For example, a plain concrete beam under a uniformly distributed load q is shown in Fig .1.1(a), when the distributed load increases and reaches a value q=1.37KN/m , the tensile region at the mid-span will be cracked and the beam will fail suddenly . A reinforced concrete beam if the same size but has to steel reinforcing bars (2φ16) embedded at the bottom under a uniformly distributed load q is shown in Fig.1.1(b). The reinforcing bars take up the tension there after the concrete is cracked. When the load q is increased, the width of the cracks, the deflection and the stress of steel bars will increase . When the steel approaches the yielding stress ƒy , the deflection and the cracked width are so large offering some warning that the compression zone . The failure load q=9.31KN/m, is approximately 6.8 times that for the plain concrete beam.Concrete and reinforcement can work together because there is a sufficiently strong bond between the two materials, there are no relative movements of the bars and the surrounding concrete cracking. The thermal expansion coefficients of the two materials are 1.2×10-5K-1 for steel and 1.0×10-5~1.5×10-5K-1 for concrete .Generally speaking, reinforced structure possess following features :Durability .With the reinforcing steel protected by the concrete , reinforced concreteFig.1.1Plain concrete beam and reinforced concrete beamIs perhaps one of the most durable materials for construction .It does not rot rust , and is not vulnerable to efflorescence .(2)Fire resistance .Both concrete an steel are not inflammable materials .They would not be affected by fire below the temperature of 200℃ when there is a moderate amount of concrete cover giving sufficient thermal insulation to the embedded reinforcement bars.(3)High stiffness .Most reinforced concrete structures have comparatively large crosssections .As concrete has high modulus of elasticity, reinforced concrete structures are usually stiffer than structures of other materials, thus they are less prone to large deformations, This property also makes the reinforced concrete less adaptable to situations requiring certainflexibility, such as high-rise buildings under seismic load, and particular provisions have to be made if reinforced concrete is used.(4)Locally available resources. It is always possible to make use of the local resources of labour and materials such as fine and coarse aggregates. Only cement and reinforcement need to be brought in from outside provinces.(5)Cost effective. Comparing with steel structures, reinforced concrete structures arecheaper. 1.37kn/m6m 200 400(a)plain concrete beam 9.31kn/m6m 200 400(b)Reinfoced concrete beam2φ16(6)Large dead mass, The density of reinforced concrete may reach2400~2500kg/pare with structures of other materials, reinforced concrete structures generally have a heavy dead mass. However, this may be not always disadvantageous, particularly for those structures which rely on heavy dead weight to maintain stability, such as gravity dam and other retaining structure. The development and use of light weight aggregate have to a certain extent make concrete structure lighter.(7)Long curing period.. It normally takes a curing period of 28 day under specified conditions for concrete to acquire its full nominal strength. This makes the progress of reinforced concrete structure construction subject to seasonal climate. The development of factory prefabricated members and investment in metal formwork also reduce the consumption of timber formwork materials.(8)Easily cracked. Concrete is weak in tension and is easily cracked in the tension zone. Reinforcing bars are provided not to prevent the concrete from cracking but to take up the tensile force. So most of the reinforced concrete structure in service is behaving in a cracked state. This is an inherent is subjected to a compressive force before working load is applied. Thus the compressed concrete can take up some tension from the load.2. HISTOEICAL DEVELPPMENT OF CONCRETE STRUCTUREAlthough concrete and its cementitious(volcanic) constituents, such as pozzolanic ash, have been used since the days of Greek, the Romans, and possibly earlier ancient civilization, the use of reinforced concrete for construction purpose is a relatively recent event, In 1801, F. Concrete published his statement of principles of construction, recognizing the weakness if concrete in tension, The beginning of reinforced concrete is generally attributed to Frenchman J. L. Lambot, who in 1850 constructed, for the first time, a small boat with concrete for exhibition in the 1855 World’s Fair in Paris. In England, W. B. Wilkinson registered a patent for reinforced concrete l=floor slab in 1854.J.Monier, a French gardener used metal frames as reinforcement to make garden plant containers in 1867. Before 1870, Monier had taken a series of patents to make reinforced concrete pipes, slabs, and arches. But Monier had no knowledge of the working principle of this new material, he placed the reinforcement at the mid-depth of his wares. Then little construction was done in reinforced concrete. It is until 1887, when the German engineers Wayss and Bauschinger proposed to place the reinforcement in the tension zone, the use of reinforced concrete as a material of construction began to spread rapidly. In1906, C. A. P. Turner developed the first flat slab without beams.Before the early twenties of 20th century, reinforced concrete went through the initial stage of its development, Considerable progress occurred in the field such that by 1910 the German Committee for Reinforced Concrete, the Austrian Concrete Committee, the American Concrete Institute, and the British Concrete Institute were established. Various structural elements, such as beams, slabs, columns, frames, arches, footings, etc. were developed using this material. However, the strength of concrete and that of reinforcing bars were still very low. The common strength of concrete at the beginning of 20th century was about 15MPa in compression, and the tensile strength of steel bars was about 200MPa. The elements were designed along the allowable stresses which was an extension of the principles in strength of materials.By the late twenties, reinforced concrete entered a new stage of development. Many buildings, bridges, liquid containers, thin shells and prefabricated members of reinforced concrete were concrete were constructed by 1920. The era of linear and circular prestressing began.. Reinforced concrete, because of its low cost and easy availability, has become the staple material of construction all over the world. Up to now, the quality of concrete has been greatly improved and the range of its utility has been expanded. The design approach has also been innovative to giving the new role for reinforced concrete is to play in the world of construction.The concrete commonly used today has a compressive strength of 20~40MPa. For concrete used in pre-stressed concrete the compressive strength may be as high as 60~80MPa. The reinforcing bars commonly used today has a tensile strength of 400MPa, and the ultimate tensile strength of prestressing wire may reach 1570~1860Pa. The development of high strength concrete makes it possible for reinforced concrete to be used in high-rise buildings, off-shore structures, pressure vessels, etc. In order to reduce the dead weight of concrete structures, various kinds of light concrete have been developed with a density of 1400~1800kg/m3. With a compressive strength of 50MPa, light weight concrete may be used in load bearing structures. One of the best examples is the gymnasium of the University of Illinois which has a span of 122m and is constructed of concrete with a density of 1700kg/m3. Another example is the two 20-story apartment houses at the Xi-Bian-Men in Beijing. The walls of these two buildings are light weight concrete with a density of 1800kg/m3.The tallest reinforced concrete building in the world today is the 76-story Water Tower Building in Chicago with a height of 262m. The tallest reinforced concrete building in China today is the 63-story International Trade Center in GuangZhou with a height a height of 200m. The tallest reinforced concrete construction in the world is the 549m high International Television Tower in Toronto, Canada. He prestressedconcrete T-section simply supported beam bridge over the Yellow River in Luoyang has 67 spans and the standard span length is 50m.In the design of reinforced concrete structures, limit state design concept has replaced the old allowable stresses principle. Reliability analysis based on the probability theory has very recently been introduced putting the limit state design on a sound theoretical foundation. Elastic-plastic analysis of continuous beams is established and is accepted in most of the design codes. Finite element analysis is extensively used in the design of reinforced concrete structures and non-linear behavior of concrete is taken into consideration. Recent earthquake disasters prompted the research in the seismic resistant reinforced of concrete structures. Significant results have been accumulated.3. SPECIAL FEATURES OF THE COURSEReinforced concrete is a widely used material for construction. Hence, graduates of every civil engineering program must have, as a minimum requirement, a basic understanding of the fundamentals of reinforced concrete.The course of Reinforced Concrete Design requires the prerequisite of Engineering Mechanics, Strength of Materials, and some if not all, of Theory of Structures, In all these courses, with the exception of Strength of Materials to some extent, a structure is treated of in the abstract. For instance, in the theory of rigid frame analysis, all members have an abstract EI/l value, regardless of what the act value may be. But the theory of reinforced concrete is different, it deals with specific materials, concrete and steel. The values of most parameters must be determined by experiments and can no more be regarded as some abstract. Additionally, due to the low tensile strength of concrete, the reinforced concrete members usually work with cracks, some of the parameters such as the elastic modulus I of concrete and the inertia I of section are variable with the loads.The theory of reinforced concrete is relatively young. Although great progress has been made, the theory is still empirical in nature in stead of rational. Many formulas can not be derived from a few propositions, and may cause some difficulties for students. Besides, due to the difference in practice in different countries, most countries base their design methods on their own experience and experimental results. Consequently, what one learns in one country may be different in another country. Besides, the theory is still in a stage of rapid development and is subjected to revision according to new findings from research. In China, the design code undergoes major revision in about every fifteen years and with minor revision in between. This book is based on the latest current code in China “Code for Design of Concrete Structures”(GB50010-2002). The studentsmust keep in mind that this course can not give them the knowledge which is universally valid regardless of time and place, but the basic principles on which the current design method in the country is established.The desk calculator has made calculations to a high degree of precision possible and easy. Students must not forget that concrete is a man-made material and a 10% consistency in quality is remarkably good. Reinforcing bad=rs are rolled in factory, yet variation is=n strength may be as high as 5%. Besides, the position of bars in the formwork may deviate from their design positions. In fact two figure accuracy is adequate for almost all the cases, rather than carrying the calculations to meaningless precision. The time and effort of the designer are better spent to find out where the tension may occur to resist it by placing reinforcement there.中文译文：钢筋混凝土结构设计一、钢筋混凝土基本概念和特点混凝土是指由水泥胶凝的水、细致聚合体、粗聚合物（碎石或沙砾）、空气、以及其他混合物的坚硬混合物。
预应力混凝土Prestressed-Concrete大学毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：预应力混凝土文献、资料英文题目：Prestressed Concrete文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14毕业设计（论文）外文资料翻译外文出处：The Concrete structure附件：1、外文原文；2、外文资料翻译译文。
1、外文资料原文Prestressed ConcreteConcrete is strong in compression, but weak in tension: Its tensile strength varies from 8 to 14 percent of its compressive strength. Due tosuch a Iow tensile capacity, fiexural cracks develop at early stages ofloading. In order to reduce or prevent such cracks from developing, aconcentric or eccentric force is imposed in the longitudinal direction of the structural element. This force prevents the cracks from developing by eliminating or considerably reducing the tensile stresses at thecritical midspan and support sections at service load, thereby raising the bending, shear, and torsional capacities of the sections. The sections are then able to behave elastically, and almost the full capacity of the concrete in compression can be efficiently utilized across the entire depth of the concrete sections when all loads act on the structure.Such an imposed longitudinal force is called a prestressing force,i.e., a compressive force that prestresses the sections along the span ofthe structural elementprior to the application of the transverse gravitydead and live loads or transient horizontal live loads. The type ofprestressing force involved, together with its magnitude, are determined mainly on the basis of the type of system to be constructed and the span length and slenderness desired.~ Since the prestressing force is applied longitudinally along or parallel to the axis of the member, the prestressing principle involved is commonly known as linear prestressing.Circular prestressing, used in liquid containment tanks, pipes,and pressure reactor vessels, essentially follows the same basic principles as does linear prestressing. The circumferential hoop, or "hugging" stress on the cylindrical or spherical structure, neutralizes the tensile stresses at the outer fibers of the curvilinear surface caused by the internal contained pressure.Figure 1.2.1 illustrates, in a basic fashion, the prestressing action in both types of structural systems and the resulting stress response. In(a), the individual concrete blocks act together as a beam due to the large compressive prestressing force P. Although it might appear that the blocks will slip and vertically simulate shear slip failure, in fact they will not because of the longitudinal force P. Similarly, the wooden staves in (c) might appear to be capable of separating as a result of the high internal radial pressure exerted on them. But again, because of the compressive prestress imposed by the metal bands as a form of circular prestressing, they will remain in place.From the preceding discussion, it is plain that permanent stresses in the prestressed structural member are created before the full dead and live loads are applied in order to eliminate or considerably reduce the net tensile stresses caused by these loads. With reinforced concrete,it is assumed that the tensile strength of the concrete is negligible and disregarded. This is because the tensile forces resulting from the bending moments are resisted bythe bond created in the reinforcement process. Cracking and deflection are therefore essentially irrecoverable in reinforced concrete once the member has reached its limit state at service load.The reinforcement in the reinforced concrete member does not exert any force of its own on the member, contrary to the action of prestressing steel. The steel required to produce the prestressing force in the prestressed member actively preloads the member, permitting a relatively high controlled recovery of cracking and deflection. Once the flexural tensile strength of the concrete is exceeded, the prestressed member starts to act like a reinforced concrete element.Prestressed members are shallower in depth than their reinforced concrete counterparts for the same span and loading conditions. In general, the depth of a prestressed concrete member is usually about 65 to 80 percent of the depth of the equivalent reinforced concrete member. Hence, the prestressed member requires less concrete, and,about 20 to 35 percent of the amount of reinforcement. Unfortunately, this saving in material weight is balanced by the higher cost of the higher quality materials needed in prestressing. Also, regardless of the system used, prestressing operations themselves result in an added cost: Formwork is more complex, since the geometry of prestressed sections is usually composed of. flanged sections with thin-webs.In spite of these additional costs, if a large enough number of precast units are manufactured, the difference between at least the initial costs of prestressed and reinforced concrete systems is usually not very large.~ And the indirect long-term savings are quite substantial, because less maintenance is needed; a longer working life is possible due to better quality control of the concrete, and lighter foundations are achieved due to the smaller cumulative weight of the superstructure.Once the beam span of reinforced concrete exceeds 70 to 90 feet (21.3 to 27.4m), the dead weight of the beam becomes excessive, resulting in heavier members and, consequently, greater long-term deflection and cracking. Thus, for larger spans, prestressed concrete becomes mandatory since arches are expensive to construct and do not perform as well due to the severe long-term shrinkage and creep they undergo.~ Very large spans such as segmental bridges or cable-stayed bridges can only be constructed through the use of prestressing.Prestressd concrete is not a new concept, dating back to 1872, when P. H. Jackson, an engineer from California, patented a prestressing system that used a tie rod to construct beams or arches from individual blocks [see Figure 1.2.1 (a)]. After a long lapse of time during which little progress was made because of the unavailability of high-strength steel to overcome prestress losses, R. E. Dill of Alexandria, Nebraska, recognized the effect of the shrinkage and creep (transverse material flow) of concrete on the loss of prestress. He subsequently developed the idea that successive post-tensioning of unbonded rods would compensate for the time-dependent loss of stress in the rods due to the decrease in the length of the member because of creep and shrinkage. In the early 1920s,W. H. Hewett of Minneapolis developed the principles of circular prestressing. He hoop-stressed horizontal reinforcement around walls of concrete tanks through the use of turnbuckles to prevent cracking due to internalliquid pressure, thereby achieving watertightness. Thereafter, prestressing of tanks and pipes developed at an accelerated pace in the United States, with thousands of tanks for water, liquid, and gas storage built and much mileage of prestressed pressure pipe laid in the two to three decades that followed.Linear prestressing continued to develop in Europe and in France, in particular through the ingenuity of Eugene Freyssinet, who proposed in 1926--1928 methods to overcome prestress losses through the use of high-strength and high-ductility steels. In 1940, he introduced thenow well-known and well-accepted Freyssinet system.P. W. Abeles of England introduced and developed the concept of partial prestressing between the 1930s and 1960s. F. Leonhardt of Germany, V. Mikhailov of Russia, and T. Y. Lin of the United States also contributed a great deal to the art and science of the design of prestressed concrete. Lin's load-balancing method deserves particular mention in this regard, as it considerably simplified the design process, particularly in continuous structures. These twentieth-century developments have led to the extensive use of prestressing throughoutthe world, and in the United States in particular.Today, prestressed concrete is used in buildings, underground structures, TV towers, floating storage and offshore structures, power stations, nuclear reactor vessels, and numerous types of bridge systems including segn~ental and cable-stayed bridges, they demonstrate the versatility of the prestressing concept and its all-encompassing application. The success in the development and construction of all these structures has been due in no small measures to the advances in the technology of materials, particularly prestressing steel, and the accumulated knowledge in estimating the short-and long-term losses in the prestressing forces.~2、外文资料翻译译文预应力混凝土混凝土的力学特性是抗压不抗拉：它的抗拉强度是抗压强度的8％一14％。
土木工程专业在多向应力作用下从混凝土的特性毕业论文外文文献翻译及原文
毕业设计（论文）外文文献翻译文献、资料中文题目：在多向应力作用下从混凝土的特性看受弯钢筋混凝土梁变化的一个基本试验文献、资料英文题目：文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：土木工程班级：姓名：学号：指导教师：翻译日期： 2017.02.14毕业设计（论文）外文翻译设计（论文）题目：宁波新城艺术宾馆2#楼结构设计与预算外文原文I：A fundamental explanation of the behaviour ofreinforced concrete beams in flexure basedon the properties of concrete under multiaxial stressM. D. KotsovosDepartment of Civil Engineering, Imperial College of Science and Technology, London (U. K.)The paper questions the validity of the generally accepted view that for a reinforced concretestructure to exhibit "ductile" behaviour under increasing load it is necessary for the stressstrain relationships of concrete to have a gradually descending post-ultimate branch.Experimental data are presented for reinforced concrete beams in bending which indicate the presence of longitudinal compressive strains on the compressive face in excess of 0.0035. It is shown that these strains, which are essential for "ductile" behaviour, are caused by acomplex multiaxial compressive state of stress below ultimate strength rather than postultimate material characteristics. The presence of a complex stress system provides a fundamental explanation for beam behaviour which does not affect existing design procedures.1. INTRODUCTIONThe "plane sections" theory not, only is generally considered to describerealistically the deformation response of reinforced and prestressed concrete beams under flexure and axial load, but is also formulated so that it provides a design tool noted for both its effectiveness and simplicity [1]. The theory describes analytically the relationship between load-carrying capacity and geometric characteristics of a beam by considering the equilibrium conditions at critical cross-sections. Compatibility of deformation is satisfied by the "plane cross-sections remain plane" assumption and the longitudinal concrete and steel stresses are evaluated by the material stress-strain characteristics. Transverse stresses and strains are ignored for the purposes of simplicity.The stress-strain characteristics of concrete in compression are considered to be adequately described by the deformational response of concrete specimens such as prisms or cylinders under uniaxial compression and the stress distribution in the compression zone of a cross-section at the ultimate limit state, as proposed by current codes of practice such as CP 110 [1], exhibits a shape similar to that shown in figure 1. The figure indicates that the longitudinal stress increases with thedistance from the neutral axis up to a maximum value and then remains constant. Such a shape of stress distribution has been arrived at on the basis of both safety considerations and the widely held view that the stress-strain relationship of concrete in compression consists of both an ascending and a gradually descending portion (seefig. 2). The portion beyond ultimate defines the post-ultimate stress capacity of the material which, Typical stress-strain relationship for concrete in compression. as indicated in figure 1, is generally considered to make a major contribution to the maximum load-carrying capacity of the beam.However, a recent analytical investigation of the behaviour of concrete under concentrations of load has indicated that the post-ultimate strength deformational response of concrete under compressive states of stress has no apparent effect on the overall behaviour of the structural forms investigated ( [2], [3]). If such behaviour is typical for any structure, then the large compressivestrains (in excess of 0.0035) measured on the top surface of a reinforced concrete beam at its ultimate limit state (see fig. 1), cannot be attributed to post-ultimate uniaxial stress-strain characteristics. Furthermore, since the compressive strain at the ultimate strength level of any concrete under uniaxial compression is of the order of 0.002 (see fig. 2), it would appear that a realistic prediction of the beam response under load cannot be based solely on the ascending portion of the uniaxial stress-strain relationship of concrete.In view of the above, the work described in the following appraises the widely held view that a uniaxial stress-strain relationship consisting of an ascending and a gradually descending portion is essential for the realistic description of the behaviour of a reinforced concrete beam in flexure. Results obtained from beams subjected to flexure under two-point loading indicate that the large strains exhibited by concrete in the compression zone of the beams are due to a triaxial state of stress rather than the uniaxial post-ultimate stress-strain characteristics of concrete. It is shown that the assumption that the material itself suffers a completeand immediate loss of load-carrying capacity when ultimate strength is exceeded is compatible with the observed "ductile" structural behaviour as indicated by load-deflexion or moment-rotation relationships.2. EXPERIMENTAL DETAILS2.1. SpecimensThree rectangular reinforced concrete beams of 915 mm span and 102 mm height x 51 mm width cross-section were subjected to two-point load with shear spans of 305 mm (see fig. 3). The tension reinforcement consisted of two 6 mm diameter bars with a yield load of 11.8 kN. The bars were bent back at the ends of the beams so as to provide compression reinforcement along the whole length of the shear pression and tension reinforcement along each shear span were linked by seven 3.2 mm diameter stirrups. Neither compression reinforcement nor stirrups were provided in the central portion of the beams. Due to the above reinforcement arrangement all beams failed in flexure rather than shear, although the shear span to effective depthratio was 3.The beams, together with control specimens, were cured under damp hessian at 20~ for seven days and then stored in the laboratory atmosphere (20o C~and 40% R.H.) for about 2 months, until tested. Full details of the concrete mix used are given in table I.2.2. TestingLoad was applied through a hydraulic ram and spreader beam in increments of approximately 0.5 kN. At each increment the load was maintained constant for approximately 2 minutes in order to measure the load and the deformation response of the specimens. Load was measured by using a load cell and deformation response by using both 20 mm long electrical resistance strain gauges and displacement transducers. The strain gauges were placed on the top and side surfaces of the beams in the longitud{nal and the transverse directions as shown in figure 4. The figure also indicates the position of the linear voltage displacement transducers (LVDT's) which were used to measure deflexion at mid-span and at the loaded cross-sections.The measurements were recorded by an automatic computer-based data-logger (Solatron) capable of measuring strains and displacements to a sensitivity of ± 2 microstrain and ±0.002 ram, respectively.3. EXPERIMENTAL RESULTSThe main results obtained from the experiments together with informationessential for a better understanding of beam behaviour are shown in figures 5 to 14. Figure 5 shows the uniaxial compression stressstrain relationships of the concrete used in the investigation, whereas figures 6 and 7 show the relationships between longitudinal and transverse strains, measured on the top surface of the beams (a) at the cross-sections where the flexure cracks which eventually cause failure are situated (critical sections) and (b)at cross-sections within the shear span, respectively. Figures 6 and 7 also include the longitudinal straintransverse strain relationship corresponding to the stress-strain relationships of figure 5.Figure 8 shows the typical change in shape of the transverse deformation profile of the top surface of the beams with load increasing to failure and figure 9 provides a schematic representation of the radial forces and stresses developing with increasing load due to the deflected shape of the beams. Typical load-deflexion relationships of the beams are shown in figure 10, whereas figure 11 depicts the variation on critical sections of the average vertical strains measured on the side surfaces of the beams with the transverse strains measured on the top surface. Figure 12 indicates the strength and deformation response of a typical concrete under various states of triaxial stress and figure 13 presents the typical crack pattern of the beams at the moment of collapse. Finally, figure 14 shows the shape of the longitudinal stress distribution on the compressive zone of a critical section at failure predicted on the basis of the concepts discussed in the following section.中文翻译I：在多向应力作用下从混凝土的特性看受弯钢筋混凝土梁变化的一个基本试验M. D. Kotsovos 伦敦皇家科学与技术学院土木工程系本文所探讨的问题是通常认为在荷载递增下钢筋混凝土结构呈现弹性状态，这必须是因为混凝土的应力-应变关系有一个逐渐递减的临界部分的真实性。
外文翻译完整版CORROSION AND PRESTRESSED CONCRETE BRIDGES
CORROSION AND PRESTRESSED CONCRETE BRIDGESAdrian T.Ciolko,P.E.1腐蚀和预应力混凝土桥梁阿德里安· T.Ciolko P.E.1AbstractThe impact on bridge reliability,of prestressing steel deterioration and tendonrupture created by corrosion mechanisms,is much more critical and rapid thanthat of any other component of a prestressed concrete bridge.Additionally,deterioration of embedded prestressing reinforcement in these structures may notnecessarily be made visible through manifestation of external distress in theConcrete.摘要腐蚀机制引起预应力钢筋的恶化和断裂，进而对桥梁的可靠性产生影响，这比对预应力混凝土桥的其他部分的影响更加严重，也更加迅速。
此外，在这些结构中，有粘结预应力钢筋的恶化也不必要通过混凝土外部糟糕的状况表现出来。
Initiating mechanisms and particular forms of corrosion affectingprestressed concrete structures are described based on the author’s experience.These degradation mechanisms include:•Chlorides and Corrosion•Concrete Carbonation Effects•Influence of Concrete Cracking•Electrochemical (Macrocell) and Pitting Corrosion•Stress Corrosion Cracking and Steel Embrittlement•Fretting Corrosion•Corrosion and Fatigue关于腐蚀影响预应力混凝土结构的最初机制和特定形式的描述是基于作者的经验。
连续梁桥文献综述范文模板
连续梁桥文献综述范文模板(中英文实用版)English:The continuous beam bridge has long been a popular choice for spans over water, highways, and railways due to its ability to distribute loads effectively and provide a smooth, uninterrupted surface for traffic.Over the years, numerous studies have been conducted to improve the design, construction, and maintenance of these bridges.This literature review aims to provide a comprehensive overview of the existing research on continuous beam bridges.中文：连续梁桥因其能有效分配荷载并提供光滑无阻的行车表面，长期以来一直是水面、高速公路和铁路上的跨度选择。
多年来，许多研究已经进行了以改善这些桥梁的设计、建造和维护。
本文献综述旨在全面介绍关于连续梁桥现有研究的概述。
English:One of the earliest studies on continuous beam bridges was conducted by Castigliano in 1854, which focused on the calculation of deflections and stresses in simply supported beams.Since then, many researchers have contributed to the development of various theories and methods for the analysis of continuous beam bridges.Some of the key theories include the principles of superposition, moment distribution,and flexibility methods.中文：最早对连续梁桥的研究之一是由Castigliano在1854年进行的，它关注的是简支梁的挠度和应力计算。
钢筋混凝土结构中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)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 concreteproduced 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 place during 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 shape and 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 forsurfaces 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 for homogeneous 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 failssuddenly-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 probableloads 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。
外文翻译中英文——预应力混凝土建筑
外文资料：Prestressed Concrete BuildingsPrestressed concrete has been widely and successfully applied to building construction of all types.Both precast pretensioned members and cast-tensioned structures are extensively employed,sometimes in competition with one another, most effectively in combination wit each other.Prestressed concrete offers great advantages for incorporation in a totalaspects of these, that is, structure plus other building. It is perhaps the “integrative”functions,which have made possible the present growth in use of prestressed concrete buildings.These advantages include the following:Structural strength; Structure rigidity;Durability;Mold ability,into desired forms and shapes;Fire resistance;Architectural treatment of surfaces;Sound insulation;Heat insulation; Economy; Availability, through use of local materials and labor to a high degree.Most of the above are also properties of conventionally reinforced concrete. Presrressing,however,makes the structural system more effective by enabling elimination of the technical of difficulty,e.g.,cracks that spoil the architectural treatment.Prestressing greatly enhance the structure efficiency and economy permitting longer spans and thinner elements.Above all,it gives to the architect-engineer a freedom for variation and an ability to control behavior under service conditions.Although prestressed concrete construction involves essentially the same consideration and practices as for all structures, a number of special points require emphasis or elaboration.The construction engineer is involved in design only to a limited extent. First,he muse be able to furnish advice to the architect and engineer on what can he done. Because of his specialized knowledge of techniques relating to prestressed concrete construction, he supplies a very needed service to the architect-engineer.Second, the construction engineer may be made contractually responsible for the working drawings;that is,the layout of tendons,anchorage details,etc.It is particularly important that he gives careful attention to the mild steel and concrete details to ensure these are compatible with his presressing details.Third, the construction engineer is concerned with temporary stresses, stresses at release, stresses in picking, handling and erection, and temporary condition prior to final completion of the structure, such as the need of propping for a composite pour.Fourth,although the responsibility for design rests with the design engineer, nevertheless the construction engineer is also vitally concerned that the structure be successful form the point of view of structural integrity and service behavior. Therefore he will want to look at the bearing and connection details, camber, creep, shrinkage,thermal movements,durability provisions,etc.,and advise the design engineer of any deficiencies he encounters.Information on new techniques and especially application of prestressing to buildings are extensively available in the current technical literature of national and international societies.The International Federation of Prestressing(I.F.P)has attempted to facilitate the dissemination of this information by establishing a Literature Exchange Service,in which the prestressing journals of some thirty countries are regularly exchanged.In addition,an Abstract is published intermittently by I.F.P The Prestressed Concrete Institute(USA)regularly publishes a number of journals and pamphlets on techniques and applications, and proceduresare set up for their dissemination to architects and engineers as well as directly to the construction engineer. It is important that he keep abreast of these national and worldwide developments, so as to be able to recommend the latest and best that is available in the art,and to encourage the engineer to make the fullest and most effective use of prestressed concrete in their buildings.With regard to working drawings, the construction engineer must endeavor to translate the design requirements into the most practicable and economical details of accomplishment,in such a way that the completed element or structure fully complies with the design requirement;for example, the design may indicate only the center of gravity of prestressing and the effective prestress force. The working drawing will have to translate this into tendons having finite physical properties and dimensions.If the center of gravity of pre-stressing is a parabolic path then,for pre-tensioning,and approximation by chords is required,with hold-down points suitably located.The computation of pre-stress losses,form transfer stress to effective stress, must reflect the actual manufacturing and construction process used,as well as thorough knowledge of the properties of the particular aggregates and concrete mix to be employed.With post-tensioning, anchorages and their bearing plates must be laid out in their physical dimension. It is useful in the preparation of complex anchorage detail layouts to use full-scale drawings, so as to better appreciate the congestion of mild steel and anchorages at the end of the member. Tendons and reinforcing bars should be shown in full size rather than as dotted lines. This will permit consideration to be given as to how the concrete can be placed and consolidated.The end zone of both pre-tensioned and post-tensioned concrete memberssubject to high transverse or bursting stresses. These stresses are also influenced by minor concrete details,such as chamfers.Provision of a grid of small bars (sometimes heavy wire mesh is used), as close to the end of a girder as possible, will help to confine and distribute the concentrated forces. Closely spaced stirrups and/or tightly spaced spiral are usually needed at the end of heavily stressed members.Recent tests have confirmed that closeness of spacing is much more effective than increase in the size of bars. Numerous small bars, closely spaced, are thus the best solution.Additional mild-steel stirrups may also be required at hold-down points to resist the shear. This is also true wherever post-tensioned tendons make sharp bends. Practical consideration of concretion dictates the spacing of tendons and ducts. The general rules are that the clear spacing small be one-and-one-half times the maximum size of coarse aggregate. In the overall section, provision must be made for the vibrator stinger.Thus pre-stressing tendons must either be spaced apart in the horizontal plane, or, in special cases, bundled.In the vertical plane close contact between tendons is quite common.With post-tensioned ducts,however,in intimate vertical contact,careful consideration has to be given to prevent one tendon form squeezing into the adjacent duct during stressing.This depends on the size of duct and the material used for the duct.A full-scale layout of this critical cross section should be ually,the best solution is to increase the thickness ( and transverse strength ) of the duct, so that it will span between the supporting shoulders of concrete.As a last rest\ort it may be necessary to stress and grout one duct before stressing the adjacent one.This is time-consuming and runs the risks of grout blockage due to leaks from one duct to the other. Therefore the author recommendsthe use of heavier duct material,or else the respacing of the ducts.The latter,of course, may increase the prestressing force required.中文翻译：预应力混凝土建筑预应力混凝土已经广泛并成功地用于各种类型的建筑。
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 program included steel stirrups, and the shear span—to—effective depth ratio, as well as amount and distribution of CFRP. The experimental results indicated that the contribution of externally bonded CFRP to the shear capacity was significant。
预应力混凝土连续梁桥外文文献_pdf
DeformationAnalysisofPrestressedContinuousSteel-ConcreteCompositeBeamsJianguoNie 1;MuxuanTao 2;C.S.Cai 3;andShaojingLi 4Abstract:Deformationcalculationofprestressedcontinuoussteel-concretecompositebeamsaccountingfortheslipeffectbetweenthe steelandconcretein terfaceunderserviceloadsisanalyzed.Asimplifiedanalyticalmodelispresented.Basedonthismodel,formulasfor predictingthecrackingregionofconcreteslabneartheinteriorsupportsandtheincreaseoftheprestressingtendonforcearederived.Atable for calculating the midspan de flection of two-span prestressed continuous composite beams is also proposed. It is found that the internalforceoftheprestressingtendonunderserviceloadscanbeaccuratelycalculatedusingtheproposedformulas.Byignoringthe increaseofthetendonforce,thecalculateddeflectionareoverestimated,andconsideringtheincreaseofthetendonforcecansignificantly improvetheaccuracyofanalyticalpredictions.Asthecalculatedvaluesshowgoodagreementwiththetestresults,theproposedformulas can be reliably applied to the deformation analysis of prestressed continuous composite beams. Finally, based on the formulas for calculating the deformation of two-span prestressed continuous composite beams, a general method for deformation analysis of pre- stressedcontinuouscompositebeamsisproposed. DOI:10.1061/ASCE ST.1943-541X.0000067CEDatabasesubjectheadings:Prestressedconcrete;Compositebeams;Deformation;Deflection;Cracking;Concreteslabs;Con - tinuousbeams .Introduction2 increasing the ultimate loading capacity;3 decreasing the deformation under service loads;4 being favorable in crack-widthcontrol;5fullyusingthematerialsandthusreducingthestructural height and overall dead load; and 6 improving the fatigueandfracturebehavior. Continuous steel-concrete composite beams are widely used in buildingsa ndbridgesforhigherspan/depthratiosandlessdeflec -tionetc.,whichresultsinsuperioreconomicalperformancecom-pared with simply supported composite beams. For continuouscomposite beams, negative bending near interior supports will resultinearlycrackingofconcreteslabandreductionofstiffness.Whenbeamsaredesignedforspanlengthsandloadsgreaterthanusual, the requirement of serviceability limit state due to unac- ceptabledeflectionandcrackwidthwouldrequireusingprestress -ingtechnique.Since Szilard 1959 suggested a method for the design and analysisofprestressedsteel-concretecompositebeamsconsider-ingtheeffectsofconcreteshrinkageandcreep,manyresearchers have developed methods for analyzing the behavior of simply supportedprestressedcompositebeams Hoadley1963;Klaiberetal.1982;Dunkeretal.1986;Saadatmanesh1986;Saadatmanesh etal.1989a,b,c;Albrechtetal.1995,Nieetal.2007 .However, continuous prestressed composite beams have not been re-searched until the late 1980s Troitsky and Rabbani 1987; Troitsky 1990; Dall’Asta and Dezi 1998, Ayyub et al. 1990, 1992a,b;Dall’AstaandZona2005.Asaresult,prestressedcon-tinuouscompositebeamshavenotwidelybeenusedpartlyduetothelackofdesigntheory. In fact, the behavior of prestressed continuous composite beamsdependsontheinteractionbetweenfourmaincomponents: thereinforcedconcreteslab,thesteelprofileofbeams,theshearconnections, and the prestressing tendons, which makes pre- stressedcontinuouscompositebeamsmorecomplexthanconven-tional ones. Dall’Asta and Zona 2005 proposed a nonlinear finiteelementmodelsimulatingthebehaviorofprestressedcon- tinuouscompositebeamsaccurately.Thisnumericalapproachisa very powerful research tool for analyzing the externally pre- stressedstructures,butitperhapsistoocomplicatedforaroutine designpractice. Comparedwithconventionalsteel-concretecompositebeams, prestressedsteel-concretecompositebeamshaveafewmajorad- vantages: 1 extending the elastic range of structural behavior; 1Professor,Dept.ofCivilEngineering,KeyLaboratoryofStructural EngineeringandVibrationofChinaEducationMinistry,TsinghuaUniv., Beijing100084,China. 2Ph.D. Candidate, Dept. of Civil Engineering, Key Laboratory ofStructural Engineering and Vibration of China Education Ministry,Tsinghua Univ., Beijing 100084, China corresponding author . E-mail:dmh03@3AssociateProfessor,Dept.ofCivilandEnvironmentalEngineering,LouisianaStateUniv.,BatonRouge,LA,70803;presently,AdjunctPro-fessor,SchoolofCivilEngineeringandArchitecture,ChangshaUniv.ofScienceandTechnology,Changsha,China.4Formerly,GraduateStudent,Dept.ofCivilEngineering,KeyLabo-ratoryofStructuralEngineeringandVibrationofChinaEducationMin-istry,TsinghuaUniv.,Beijing100084,China.Note.ThismanuscriptwassubmittedonAugust10,2008;approved on April 20, 2009; published online on October 15, 2009. Discussion periodopenuntilApril1,2010;separatediscussionsmustbesubmitted for individual papers. This paper is part of the Journal of Structural Engineering ,Vol.135,No.11,November1,2009.©ASCE,ISSN0733- 9445/2009/11-1377–1389/$25.00.Asprestressingtechniqueisaneffectivewaytoreducedefor- mation and crack width under service loads, particular attention hastobepaidtothedeformationcalculationofprestressingcon- tinuouscompositebeams.Themainobjectiveofthisresearchis todevelopcalculationmethodsforthedeformationofprestress-ing continuous composite beams based on the reduced stiffnessJOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009/1377Thedownwardconcentratedforceappliedbytendonsattheinte-rior support is not shown in the figure as the force is applieddirectlyonthesupport.Therigidityalongthebeamcanbecon-sideredasunchangedinthisstagesincethecrackingofconcreteusually does not occur.The section properties can be calculatedby the transformed section method ignoring the slip effect be-tweensteelandconcreteinterfaceatthisstage.Itisassumedthatthedistributionofmomentalongthebeamduetotheprestressingforcekeepsunchanged.Oncealltheparametershavebeendeter-mined,deformationinthefirststage f1canbedirectlycalculatedbymethodsofstructuremechanics.Fig.1.Sketchoftwo-spanprestressedcontinuouscompositebeammethodthatwasdevelopedforconventionalcontinuouscompos-itebeams NieandCai2003.Theproposedmethod,verifiedbytestresults,issuitablefordesignpractice.In the second stage shown in Fig. 2b, application of theexternal force P results in the increase of downward deflection⌬f andachangeofprestressingtendonforce⌬T.Intheregionof2TheoreticalStudysaggingmoment,thereducedflexuralstiffness B=E1I11+ isusedduetotheslipeffects,whereisstiffnessreductioncoeffi-cient according to the reduced stiffness method Nie and Cai2003,andtheaxialstiffnessEAiscalculatedbythetransformedsectionmethod.IntheregionofhoggingmomentintherangeofnL neareachsideoftheinteriorsupports,concreteisconsideredno longer in service due to cracking. In this case the bendingrigidityE2I2 andaxialrigidityE2A2 canonlyincludethecontri-butionofthereinforcementandsteelmaterials,andparameter␣andaredefinedas␣=B E2I2,and=EA E2A2.Actually,inthesecondstage,concreteinthehoggingmomentmaystillcontributetostiffnessbecauseoftheprestressingforce.Therefore, the partial interaction between the steel and concreteshould be considered for a rational analysis. For simplicity, thiskind of interaction effect is considered in the present study byadjustingthevalueofnL insteadofactuallymodifyingthestiff-nessofcompositebeamsnearthesupports,whichresultsinonlysmallerrorsas willbeverifiedbytheexperimentsanddiscussedlater.AnalyticalModelPrestressed continuous composite beams discussed in this paperareshowninFig.1wheretheprestressingtendonsarelaidoutasfold lines or straight lines for the convenience of construction.Thestraightlinescanbeconsideredasaspecialcaseofthefold-linetypewith=0incalculation.Thepositionoftendonscanbeeitherinternalorexternal,whichwillnotinfluencethemethodofanalysis.Thus,theresearchinterestinthispaperisconcentratedonatwo-spanprestressedcontinuouscompositebeamwithfold-line tendons as shown in Fig. 1, and the methodology can be appliedtootherkindsofprestressedcontinuouscompositebeams.Thecalculationmodelofprestressedsteel-concretecompositebeamsisshowninFig.2.Theprocessofloadingcanbedividedinto two st ages. In the first stage shown in Fig. 2a, beams areinitially prestressed by tendons and the equivalent loads appliedto the continuous beams by tendons are composed of two parts.Thefirstpartincludesaxialcompressionforce T andmomentT0e0atthebeamends,wheree0=distancefromthebeamanchortotheneutralaxisofthetransformedsection,positivebelowneu-tral axis. The second part includes vertical concentrated loadsappliedbytendons.ForceequilibriumshowninFig.3givesthevalueoftheequivalentconcentrateforceFappliedbythetendonsasT0sin,whichequalstoT0approximatelyasisverysmall.Inordertoobtainthedeflectionofthecompositebeamsinthisstage, the length of cracking region of concrete slab at interiorsupports, defined by n, should be determined first. For conven-tionalcontinuouscompositebeams,itisfoundinpreviousstudiesandexperimentsthattaking0.15forthenvaluewillbeaccurateenough for design Nie et al. 2004. However, for prestressedcontinuous composite beams, the length of cracking region ofconcreteslabissmallerthantheconventionones.Furthermore,nisrelatedtotheprestressingdegreedirectly,whichhasbeenveri-fied by tests. The other parameter ⌬T is also very essential forcalculatingthedeflection.Since the materials are generally linear elastic under serviceload conditions, the principle of superposition can be used toobtainthetotaldeflectionas f1+⌬f2,where f1canbecalculateddirectlybymethodsofstructuralmechanics.Inthisstudy,wearemore concerned about the increase of deflection under serviceloads, i.e., ⌬f2. Therefore, this paper will only investigate theincrease of deflection in the second stage, and for convenience,⌬f2 will be rewritten as f hereafter.According to the discussionmadeabove,thecoreofdeformationcalculationistodeterminethe values of n and ⌬T, which will be discussed further in thefollowingparts.Fig. 2. Calculation model of prestressed continuous steel-concretecompositebeam:afirstloadingstage;b secondloadingstageThecableslipatthesaddlepointsisacomplexbehavioroftheexternally prestressed composite beams. The slip friction at thesaddle points can influence the behavior of beams under serviceloads. Negligible friction occurs by using individually coatedsingle-strand tendons Conti et al. 1993 and the assumption ofnegligiblefrictioncanbefoundinthepreviousmodel Dall’Astaand Zona 2005. This assumption is also used in the followinganalyticalstudies.Fig.3.Equivalentloadappliedtothebeambytendons1378/JOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER200951M k =0.85M ek = m 1−m P k L640where M ek =moment due to P k ignoring the moment redistribu- tion.The relationship between the service load and the initial pre- stressingforcecanbederivedusingEqs.5and 6as40T 0 51m 1−m L 2 e W20T 0 17 0 P k =++ 7A Undertheapplicationofexternalforceandprestressingforce,thedistributionofmomentalongthebeamisshownasFigs.4 bandc , respectively. The tension stress at the top of concrete at the boundaryofthecrackingregionequalstozero,whichleadstoM T x=nL +M P x=nL −T=08W AFig.4.Theoreticalanalysisofthelengthofcrackingregionofcon-creteslab:a calculationmodeloftwo-spanprestressedcontinuouscompositebeams;b momentdistributionduetoprestressingtendon force;and c momentdistributionduetoexternalloadswhere T=tendon force under service load conditions. Compared withtheinitialprestressingforce,theincreaseoftendonforceisrelatively small, and T can be taken proximately as T 0; M T x =moment distribution along the beam due to the prestressing force,andM P x =momentdistributionalongthebeamduetothe serviceload.TheyarecalculatedasPredictionofCrackingRegionofConcreteSlabx =3Te 02 Lx −21Te 0+ −23m 2+32m+1 T x In this part, the length of cracking region of concrete slab overinteriorsupportswillbetheoreticallyanalyzedbasedonthecal- culation model shown in Fig. 4a . After the initial force T 0 is prestressed,astructuralanalysisgivesthesaggingmomentatthe interiorsupportasM T−23m 1−m T L 0Յx ՅnL95140 51 51 =T 0e 0 +32m 1−m T 0L M P x = m 2−40 m −1 P k x+ m 1−m P k L 0Յx ՅnLM T0140210Accordingly,theinitialcompressivestressatthetopofconcreteslabattheinteriorsupportiscalculatedasIntroducing Eqs. 7, 9, and 10 into Eq. 8 leads to theex-pressionofnasafunctionof pc =M T0+T 0= A T 0e 0+ 2W 3m 1−m T 0L 2W +TA 2A −1 0 n=B −CA 11Wwhere W=section modulus of transformed composite section at the top of concrete flange and A=cross-sectional area of trans-formedsection.Themomentneededtoeliminatethecompressivestressatthe interiorsupportisobtainedaswhereA,B,andCcanbecalculatedas1 W +321−m me 0L A=2+Ae 03 3 3 1 m L + m B=2 + − m+ 2 2 e 0 M 0=pc W=12T 0e 0+32m 1−m T 0L+TA 0W 3C=51m 2−51m −4051m 2−51mTheprestressingdegreeisdefinedas=MM 4From Eq. 11 we can see that the main factors influencing the rangeofconcretecrackingregionincludetheprestressingdegree ,theparameterW Ae 0,theparameterm L e 0,andtheloading positionm.TheireffectsonnareplottedinFigs.5–7.FromFigs.5–7 we can see that the length of concrete cracking region falls moreandmorequicklyastheprestressingdegreerises.Whenthe prestressingdegreeistakenas1,thelengthofconcretecrackingregion is zero, referred to as fully prestressed composite beams. Similarly,azerooftheprestressingdegreeresultsinthelengthof concrete cracking region being as 1C, which depends only on theloadingpositionmandcorrespondstoconventionalcomposite beams. Fig. 5 indicates how n varies within the usual range of parameter W Ae 0 when the other parameters are fixed. It iskwhereM k =momentattheinteriorsupportduetoserviceload P k excludingprestressingeffect .IntroducingEq.3intoEq.4givesM k =T20e 0+3m 1−m T 0L+T 0W 52 A It is found in experiments that the moment redistribution coeffi-cient ␣a attheinteriorsupportcanreachabout15%underservice loadconditions.Therefore,15%isusedtocalculatethemoment attheinteriorsupportunderserviceloadsapproximatelyasJOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009/1379Fig.5.Influenceofparameter W Ae0onn Fig. 8. Comparison among test results, theoretical results and sim-plifiedtheoreticalresultsfoundthattheinfluenceofparameter W Ae0onnisveryslightandcanbeignored.In most cases, the neutral axis in the region of positive mo-me ntisadjacenttothesteeltopflange,andtheprestressingten-dons are adjacent to the steel bottom flange. According to thesketchshowninFig.1,mLrepresentstheverticaldistancefromthebeamanchortothecenteroftendonstakenproximatelyasthepositionofthesteelbottomflange,leadingtothefollowing:gion,andinlowprestressingdegreeregionitvariesfrom0.15to0.20approximatelywhenmvarieswithintheusualrange.Sincetheactuallengthofconcretecrackingregionisslightlyshorter than the theoretical result due to the assumption that thetensile strength of concrete and the increase of tendon force arenegligible, Eq. 11should be modified to a certain extent. Fur-thermore, except for , the other three parameters all slightlyinfluencethe n value.Thus,Eq.11canbesimplifiedconsider-ingthefollowingfactors:mL+e0h s mL hs−1 12e0 e01. RelationshipformatbetweennandasdefinedbyEq.11is maintained by adjusting only the coefficient in the equa-tion.Sincetheheightofthesteelbeamh isabout4to8timesofthesanchoreccentricitye0,theparametermL e0variesfrom3to7.WithinthisrangewecanconcludefromFig.6thatthevariationofparametermL e0willnotsignificantlyinfluencethevalueofn.2.3.Thenewequationcanreducetoconventionalnonprestressedcase,i.e.,when=0,n =0.15.The parameter W Ae0 and mL e0 can be taken as theaveragevalueswithintheusualrange.Consequently,Eq.11issimplifiedas Fig. 7 shows how the loading position m influences the nvalue.The n approaches to unity in high prestressing degree re-n=143−−20113Thecomparisonbetweentestresults discussedlater ,theoreticalresults, and simplified modified theoretical results is shown inFig.8,whichprovesthatEq.13isreasonableandaccurateforthecalculation.PredictionofTendonForceTheincrementoftendonforceduetoexternalloadscanbepre-dicted by developing the equilibrium equation, the deformationcompatibilityequation,andthephysicalequationforthestructuresystem.Theexternalloadsmainlyresultinbeammomentswhosedistribution depends on the loading conditions. The change ofprestressing tendon forces mainly result in axial forces and mo-ments, which can be solved by a simple structural analysis asshowninFig.9.Fig.6.InfluenceofparameterL e0onnTheeffectofprestressingforceincrement⌬Tisresolvedintotwo parts in Fig. 9a, namely the equivalent vertical forces andhorizontalaxialforcesatbeamends.Thepositionchangeofneu-tralaxisintheregionofhoggingmomentneartheinteriorsupportinfluencesthemomentdistributionduetoprestressingforce.Asaresult,acoefficient=e02e0isdefinedheretodescribeit,wheree02representstheverticaldistancefromtheprestressingtendontotheelasticneutralaxisintheregionofhoggingmomentasshowninFig.9a withpositiveforbeingbelowtheneutralaxis.In order to solve the expression of R1 and R2 in Fig. 9a, Fig.7.Influenceofparameter monn1380/JOURNALOFSTRUCTURAL ENGINEERING©ASCE/NOVEMBER2009Fig.9.Distributionofinternalforcesduetoprestressingtendonforces:a distributionofmomentsduetotheincreaseofprestressingtendon forces;b distributionofaxialforcesduetotheincreaseofprestressingtendonforcesdeformation compatibility equations at Point 1 as shown in Fig. 9a underthetwoloadcasescanbedevelopedasfollowingEqs. 14and 15 ,respectively=⌬TL P⌬P19E A P Pwhere L P =length of the prestressing tendons; E P A P =axial stiff-nessoftheprestressingtendons;andYoung’smodulusoftendons E p canbetakenproximatelyasYoung’smodulusofsteelsb . Fortheconvenienceoffurtherderivations,thefollowingdefi- nitionsareintroduced:1 114⌬ =⌬ −2R 1⌬T 11=0 1 1,⌬T22R ⌬Te 0 11=0 2 21,⌬T 15⌬ =⌬ −1 L 11where ⌬ =actual vertical displacement of Point 1 under Load e 2 e=e 1,=e 1202Case 1;⌬ =actualverticaldisplacementofPoint1underLoad 1 Case 2;⌬1,1⌬T =verticaldisplacementofPoint1underLoadCase 21,⌬Twhere e 1 and e 2 are shown in Fig. 10a with a positive value beingforbelowtheneutralaxis.Accordingly,fold-lineoftendons hasanegative andstraight-lineapositive value.Intheregionofhoggingmoment,sinceonlythetopreinforce- mentbarsandthesteelbeamareconsideredinthecalculation,the slipeffectcanbeexcluded,whichresultsinthestrainofthesteel fiberattheheightleveloftendonsas1 with the interior support removed; ⌬ =vertical displace- ment of Point 1 under Load Case2 with the interior support removed; and 11=vertical displacement of Point 1 produced by unit vertical force applied on Point 1 with the interior support removed.SolvingEqs.14and 15givestheexpressionofR 1andR 2 inFig.9a asinthefollowing:R 1=−3␣−1n 2+6␣−1n −3m 2+3m+22␣−1n 3−6␣−1n 2+6␣−1n+216−3␣−1n 2+6␣−1n+3 2␣−1n 3−6␣−1n 2+6␣−1n+2R 2=17Theexternallyprestressedcompositebeamsdonotdeformcom-patiblywithprestressingtendonsatallsections.However,inad- ditiontothetwoendanchors,severalintermediateconnectionsor calleddeviatorsareprovidedfortheprestressingtendonssothat thedeformationcompatibilityatthesepointsismaintainedduring theloadingprocess,ensuringtheglobaldeformationcompatibil- ity between the prestressing tendons and the composite beam. From the global deformation compatibility conditions, the total deformationoftheprestressingtendonsequalstotheintegration ofthestrainofthesteelfiberattheheightleveloftendons,thus leadingtothedeformationcompatibilityequationas͵2L⌬P =b x dx 18where ⌬ =total deformation of the prestressing tendons and pFig. 10. Distribution of eccentricity of the tendons to the elastic neutralaxisoftransformedsectionalongthebeam:a positionofthe elasticneutralaxis;b actualdistributionofe x ;and c si mplified distributionofe xb x =strain of the steel fiber at the height level of tendons at sectionxfromthesidesupport.Thedeformationofprestressingtendonscanalsobecalculated asJOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009/1381Fig. 11. Analytical model for calculating the strain of steel beamundermomentinthesaggingmomentregions−= e x+N⌬T xEA␣M P x+M⌬T 21b BFig. 12. Calculation diagram of midspan deflection of prestressedcontinuouscompositebeamswhere M P x, M⌬T x, and N⌬T x represent the distribution of internalforcesalongthebeamduetoboththeexternalloadsandtheincreaseofprestressingtendonforces.In the region of sagging moment, the distribution of strainsacrosstheheightofacompositebeamsectionisshownasFig.11.Due to the slip effect, the slip strain which results in the addi-tional curvature exists in the adjacent fibers at the interface ofconcreteandthesteelbeam.Therefore,itisnecessarytomodifytheelasticresultsofthesteelstrains.ItcanbeseenfromFig.11that the strain of the steel fibers where the prestressing tendons arepositionedintheregionofsaggingmomentcanbecalculatedaseA␣,M,PB27⌬T=1 +Be C1L+C2e02LEA0where C1 and C2 are coefficients related to ␣, , m, n, and ,calculatedasfollows:C1=12␣−R1n2−␣−R1−1n− 21R1+m2−m−21+=be−⌬b2228 bwhere ⌬b=additional strain due to the slip effect and be=strain calculated by beam theory and the transformed sectionmethod29C2=21␣−R2n2−␣−R2−1n− R −1122whereA0=transformedsectionalareaofthecompositebeamand be=M P x+M⌬T x e prestressingtendons,calculatedas23B1+A P AA0=1−n+n A P+L P2L A 30 Assumingthatthesteelbeamandconcreteflangehavethesamecurvature and the distribution of stresses and strains across theheight of a section due to the slip effect is linear, the additionalstraincanbeobtainedasA␣external loads and the coordinate axis, multiplied by ␣ in thehoggingmomentand insaggingmoment,positiveforsagging,=areabetweenthegraphofmomentdistributionduetotheM,P⌬b=⌬y−e24momentandnegativeforhoggingmoment.FortheloadingcaseshowninFig.1,A␣,=2C PL2;thenputtingthisexpressionof Thereducedstiffnessmethod NieandCai2003gives M,P 1 kA␣,into Eq. 27, we can finally obtain the increase of tendonM,Pforce due to the two concentrated loads symmetric to the mid- ⌬=EIM =M P x+M⌬T x25span,asaspecialcaseofEq.27 ,asB 1+eC1P k L Basedontheanalysisaboveandconsideringthesteelstraindueto axial forces, the strain of the steel fiber at the height level ofsteeltendonsintheregionofsaggingmomentcanbederivedas⌬T= 31B+e C1L+C2e0EA01−The increase of tendon force due to other loading cases can beobtainedusingthesamemethodology.+=Be y x+N⌬T xM P x+M⌬Tb 1+ e EA=BeM P x+M⌬T x+N⌬T xEA26DeformationCalculationOncethelengthofconcretecrackingregionattheinteriorsupportandtheincreaseofprestressingtendonforcearedetermined,thedeformation can be obtained following the same procedure asconventional continuous composite beams Nie and Cai 2003.For the loading case shown as Fig. 1, the midspan deflection ofprestressed continuous composite beams can be calculated fromthecalculationdiagramasFig.12.where reflects the slip effect between steel and concrete inter-faceintheregionofsaggingmoment.Considering the equilibrium conditions, deformation compat-ibilityconditions,andphysicalconditionsaltogether,theincreaseof tendon force can be predicted from simultaneous equationsfromEq.18toEq.26as1382/JOURNALOFSTRUCTURALENGINEERING©ASCE/NOVEMBER2009M=M P +⌬T ·M ⌬¯T 34Finally,selecttherelatedformulasfromFig.12andthecalcula-tion diagram for conventional continuous beams Nie and Cai 2003,andobtainthemidspandeflectionsolutionsforthemidd le andsidespans.Inthedesignpractice,wealwayshopethattheintroductionofinternal moment by the prestressing tendons can act in opposite direction to that induced by the externally applied loads. As a result, the tendon profile is usually designed according t o the momentdiagramofexternalforcesassummarizedinFig.13a , inwhichtwoappliedloadscoincidewiththepointofchangeinangle in the prestressing tendons. In fact, the proposed general method for deformation calculation can also be used for the ap- plication of any given force at any arbitrary location along the beamspansinceEqs.33and 34donotcontainingtheassump- tionthatthediagramofM P andM ⌬¯T shouldsatisfysomecertain relationship.M P andM ⌬¯T canbeobtainedaccordingtotheactual load location and tendon profile, respecti vely, when using Eqs. 33and 34formoregeneralanalysis.Fig. 13. Deformation calculation of three-span prestressed continu- ouscompositebeam:a sketchofthree-spanprestressedcontinuouscomposite beams; b calculation model of three-span prestressed continuouscompositebeams;c M P graph;and d M ⌬¯T graphExperimentalProgram DescriptionofTestsInordertovalidatethedevelopedanalyticalprocedures,onenon-prestressed CCB-1 and six prestressed PCCB-1 to PCCB-6continuouscompositebeamsweretested Li2003.Thedetailsofthese seven specimens are given in Table 1 and the layout isshowninFig.14.Thetestedbeamsare8mlongwithtwoequalspans,andthecrosssection Fig.15consistsofasteelboxbeamandaconcreteslabof500 mm ϫ70 mm.Theexpressionforthemidspandeflectioncanbederivedas f=f 1+f 2+f 3+f 4 32 where f 1–4 canbecalculatedusingtheformulasinFig.12. GeneralMethodforDeformationCalculationCCB-1isaregularsteel-concretecontinuouscompositebeam without prestressing tendons. For PCCB series, the prestressingtendons were anchored at the two beam ends with two interme-diateconnectionswithineachspanandoneattheinteriorsupportsothattheycoulddeformcompatiblywiththesteelbeamattheseconnecting points during the loading process. The main factorsinfluencing the behavior of prestressed continuous c ompositebeams are the form of tendons, the number of tendons, and thepositionoftendons.Inordertomakeacomprehensiveinvestiga-tion on the prestressed continuous composite beams, the PCCBseriesweredesignedas Fig.14• PCCB -1:straight-line,one-tendon,internalprestressedbeam; • PCCB -2:straight-line,two-tendon,internalprestressedbeam; • PCCB -3:fold-line,one-tendon,internalprestressedbeam; • PCCB -4:fold-line,two-tendon,internalprestressedbeam;• PCCB -5:straight-line,two-tendon,externalprestressedbeam;and• PC CB-6:fold-line,two-tendon,externalprestressedbeam. Thespecimensweretestedwithtwoservocontrolledhydrau-licjacks,witheachforcebeingspreadintotwosymmetricpointloads as shown in Figs. 16 and 17.The test setup also included deflectionmeasurementsatthemidspanan dstrainmeasurements atcriticalsectionsbystraingaugesgluedonthelongitudinalre- inforcement,steelbeam,concreteslab,andprestressingtendons.Strains and deflections were measured automatically by a data acquisitionsystem IsolatedMeasurementPodsystem controlled byacomputer.Thearrangementofmeasuringdevicesissumma-rizedinFig.18indetail. Usingthedevelopedmethodologyforcalculatingthedeformationof two-span prestressed continuous composite beams, the defor-mationofprestressedcontinuouscompositebeamswithanynum-berofspansatserviceabilitylimitstatescanbeobtained.Asanexample Fig. 13a shows the sketch of a three-span prestressedcontinuouscompositebeam.First,thelengthofconcretecrackingregion at every support n i can be determined according to Eq.13, based on which the calculation model for prestressed con-tinuous composite beams can be developed as shown in Fig.13b . Second, the moment diagrams due to external loads M P andduetotheunitchangeofprestressingtendonforceM ⌬¯T can be solved as shown in Fig. 13c and Fig. 13d , respectively. Thenthechangeofprestressingtendonforcecanbecalculatedas A M,P,⌬T= 2LB 33 ␣,eEA 0−A M,⌬T ¯ whereA ␣,=areabetweenthediagramofM P andthecoordinate M,Paxis, multiplied by ␣ for the hogging moment and for thesagging moment, positive for the sagging moment and A ␣M,⌬,¯T =areabetweenthediagramofM ⌬¯T andthecoordinateaxis,mul- tipliedby ␣forthehoggingmomentand forsaggingmoment,positive for the sagging moment. The other parameters are the sameasthoseintheformulasfortwo-spanprestressedcontinuous compositebeams.The principle of superposition gives the moment distributionalongthebeamasThe height of beam supports was adjustable, hinged for the interioroneandslidingforthesideones.BeforethebeamswereJOURNALOFSTRUCTURALENGINEERING©ASCE/NO VEMBER2009/1383。
建筑类外文文献及中文翻译
forced concrete structure reinforced with anoverviewReinSince the reform and opening up, with the national economy's rapid and sustained development of a reinforced concrete structure built, reinforced with the development of technology has been great. Therefore, to promote the use of advanced technology reinforced connecting to improve project quality and speed up the pace of construction, improve labor productivity, reduce costs, and is of great significance.Reinforced steel bars connecting technologies can be divided into two broad categories linking welding machinery and steel. There are six types of welding steel welding methods, and some apply to the prefabricated plant, and some apply to the construction site, some of both apply. There are three types of machinery commonly used reinforcement linking method primarily applicable to the construction site. Ways has its own characteristics and different application, and in the continuous development and improvement. In actual production, should be based on specific conditions of work, working environment and technical requirements, the choice of suitable methods to achieve the best overall efficiency.1、 steel mechanical link1.1 radial squeeze linkWill be a steel sleeve in two sets to the highly-reinforced Department with superhigh pressure hydraulic equipment (squeeze tongs) along steel sleeve radial squeeze steel casing, in squeezing out tongs squeeze pressure role of a steel sleeve plasticity deformation closely integrated with reinforced through reinforced steel sleeve and Wang Liang's Position will be two solid steel bars linkedCharacteristic: Connect intensity to be high, performance reliable, can bear high stress draw and pigeonhole the load and tired load repeatedly.Easy and simple to handle, construction fast, save energy and material, comprehensive economy profitable, this method has been already a large amount of application in the project.Applicable scope : Suitable for Ⅱ , Ⅲ , Ⅳ grade reinforcing bar (including welding bad reinforcing bar ) with ribbing of Ф 18- 50mm, connection between the same diameter or different diameters reinforcing bar .1.2 must squeeze linkExtruders used in the covers, reinforced axis along the cold metal sleeve squeeze dedicated to insert sleeve Lane two hot rolling steel drums into a highly integrated mechanical linking methods.Characteristic: Easy to operate and joining fast and not having flame homework , can construct for 24 hours , save a large number of reinforcing bars and energy.Applicable scope : Suitable for , set up according to first and second class antidetonation requirement -proof armored concrete structure ФⅡ , Ⅲ grade reinforcing bar with ribbing of hot rolling of 20- 32mm join and construct live.1.3 cone thread connectingUsing cone thread to bear pulled, pressed both effort and self-locking nature, undergo good principles will be reinforced by linking into cone-processing thread at the moment the value of integration into the joints connecting steel bars.Characteristic: Simple , all right preparatory cut of the craft , connecting fast, concentricity is good, have pattern person who restrain from advantage reinforcing bar carbon content.Applicable scope : Suitable for the concrete structure of the industry , civil building and general structures, reinforcing bar diameter is for Фfor the the 16- 40mm one Ⅱ , Ⅲ grade verticality, it is the oblique to or reinforcing bars horizontal join construct live.conclusionsThese are now commonly used to connect steel synthesis methods, which links technology in the United States, Britain, Japan and other countries are widely used. There are different ways to connect their different characteristics and scope of the actual construction of production depending on the specific project choose a suitable method of connecting to achieve both energy conservation and saving time limit for a project ends.钢筋混凝土结构中钢筋连接综述改革开放以来，随着国民经济的快速、持久发展，各种钢筋混凝土建筑结构大量建造，钢筋连接技术得到很大的发展。
土木工程 桥梁 毕业设计 外文文献翻译 中英文
文献翻译Bridge Maintenance TechniquesEssential maintenance generally involves strengthening or replacement of bridge elements . Strengthening techniques include welding , plate bonding and external post-tensioning which increase the stiffness of bridge decks . Replacement of elements has been used for deck slabs and beams, piers and columns. The primary purpose of essential maintenance is to increase the load carrying capacity and the reason for the inadequate capacity is secondary . If the reason is simply increased loading the maintenance can be limited to increasing the capacity , but if the reason is deterioration then maintenance must also include repairs and preventative maintenance.The selection of the maintenance method for repairs prevention depends primarily on the cause of deterioration . For steel construction the main cause of deterioration is corrosion and regular maintenance painting should be carried out to prevent the steel from corroding . If corrosion does occur then the only repair option is to grit blast back to shiny metal before repainting . An assessment of load carrying capacity should be carried out if corrosion has resulted in a significant reduction of steel section .The selection of repair and prevention methods for concrete construction is more complex because there are numerous causes of concrete deterioration .The deterioration of reinforced concrete can be conveniently sub-divided into deterioration of the concrete and deterioration of the steel reinforcement . The main causes of concrete deterioration are sulphates , free-thaw cycles and alkali-silica reaction(ASR). Deterioration can also be related to poor mix design and construction process such as compaction and curing . These types of deterioration can only be prevented by actions taken at the time of construction ; there are no effective preventative actions that can be taken after construction. For example where the environment is known to contain significant quantities of sulphide it is sensible to consider the use of sulphate resisting Portland cement . In regions experiencing large numbers of freeze-thaw cycles frost damage to concrete can be prevented by adding air entraining agent to the concrete mix . Frost damage is worse in concrete that is saturated with salty water so techniques such as waterproofing membranes and silane treatments may be helpful . Alkali-silica reaction between aggregates and the alkali in cement can be prevented by avoiding the most reactive types of aggregate and by keeping the alkali content of the cement below the designated limit . To set up damaging stresses in concrete the ASR requires water so procedures to reduce the water content such as waterproofing membranes and silane treatments may help . If these forms of concrete deterioration take place the only viable repair method is concrete replacement which may be extensive especially for ASR where entire sections can be affected . Sulphate and freeze-thaw damage normally occur only in the coverzone of the concrete . It is important to note that deterioration of the concrete will increase the risk of corrosion to the reinforcement because steel depassivators , like chlorides and carbon dioxide , will be able to move more easily through the concrete to the reinforcement .Deterioration of the reinforcing steel is caused by corrosion and can be prevented by actions taken at the time of construction and for a period after construction . Preventative techniques that can be applied at construction include the use of epoxy coated mild steel , stainless steel of carbon or glass fibre reinforcement , inhibitors , cathodic protection , anti-carbonation coatings , silane treatments and waterproofing membranes . All of these techniques , except the last three , directly protect the reinforcement against corrosion and to date , have been used only occasionally largely on grounds of cost . Waterproofing membranes , silane treatments , and anti-carbonation coatings are applied to the concrete and are designed to slow down the ingress of carbon dioxide and chlorides into the concrete thereby increasing the age of the structure when the reinforcement begins to corrode . These techniques can be used after construction because they are applied to the concrete surface and they should be effective , providing corrosion of the reinforcement has not already begun . It is important not to overlook the importance of well compacted and cured, low water : cement ratio concrete in preventing reinforcement corrosion.When corrosion of the reinforcement occurs it result in a loss of steel section and/or cracking, spalling and delamination of concrete due to the stresses produced as a result of the low density of rust compared with density of the steel . Reinforcement corrosion repair methods have two main functions , to crete replacement ; cathodic protection ; desalination ; realkalization.Concrete replacement has to be used to repair the damage caused by corrosion regardless of which technique is used to stop corrosion . Concrete replacement can also be used to stop corrosion although this involves the removal of all the carbonated and chloride contaminated concrete even though it is physically sound . This often means that concrete repairs to stop corrosion are not economically viable . Cathodic protection can be applied at any time to stop corrosion caused by carbonation or chlorides . It functions by making the reinforcing steel cathodic with respect to an external anode system . Cathodic protection requires a permanent electrical installation . Desalination can be used to stop corrosion caused by chlorides and it works by migrating chloride ions towards an external anode and away from the reinforcing steel in an electric field ; this process takes about 6 weeks . Realkalization stops corrosion caused by carbonation and it works by migrating sodium ions from an external anolyte into the concrete where in combination with the hydroxyl ions generated on the reinforcing steel due to the electric field , the alkalinity is raised to a level where the steel re-passivates . Realkalization takes about 4 weeks . Desalination ,realkalization and concrete repair are not normally used in conjunction with a preventative treatment such as silane or an anti-carbonation coating to increase the life of the repair .Cathodic protection does not requireadditional preventative measures because it is a permanent installation , but the anodes do require periodic replacement.大桥维修技术大桥的基本的维修大体上包括加强和更换桥的基本元素。
预应力混凝土连续梁的分析大学毕业论文外文文献翻译
毕业设计（论文）外文文献翻译文献、资料中文题目：预应力混凝土连续梁的分析文献、资料英文题目：文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14预应力混凝土连续梁的分析1 简介这次会议召开的主要目的是对结构的分析和开发，而不是讨论材料的强度，但是要想有效在使用预应力混凝土材料需要依靠适当的结构分析和对材料的性能的认识。
预应力混凝土结构的设计在没有专家参与的情况下，人们在进行设计时会出现很多错误或者会花费大量的时间进行方程式的推导求解。
预应力混凝土材料和其他材料的在基本性能上有很大的区别。
静定结构在不加荷载的情况下是不会有应力产生的，内力的解是在完全可行解内；在超静定结构当中，由于各种因素的影响，引起了缆绳的徐变和热效应从而导致出现各种自应力。
这些问题是如何被认识并且如何处理的呢?自从19世纪末钢筋混凝土开始被埃纳比克应用和发展以来（库萨克1984），它被人们认识到如果把预应力钢筋砼混凝土放在一起，它们能够很有效的结合起来。
如果它们能够结合在一起这样的话就会降低开裂的可能性，并且能够增加刚度和提高耐久性。
通过Leonhardt (1964) 和Abeles (1964)对这些尝试详细的介绍，我们可知早期尝试的失败是因为初始预应力的过早消失，残余的结构行为仿佛是被加强了。
1927年弗莱西奈在维希附近的阿列河上完成了对浅拱在三个桥梁上的下沉的观察，这直接导致了预应力混凝土的发展（Freyssinet 1956）。
第二次世界大战只有Boutiron桥幸存下来(图1)。
迄今为止它被人们认为是一个杨氏模数混凝土而被固定保留下来，但是他认为过度的变形会导致徐变的发生，这就解释了早期试验当中为什么预应力会消失。
由于弗莱西奈使高强钢筋能够被正确使用，因而一些预应力会在徐变后也将存在，这就导致高性能混凝土被使用，使得徐变的总变量达到最小。
弗莱西奈早期是在各个地方书写关于预应力混凝土的工作。
预应力混凝土连续梁桥外文文献_pdf
预应力钢-混凝土连续组合梁的变形分析摘要:对预应力钢-混凝土连续组合梁在正常使用极限状态下的变形计算进行分析。
分析考虑钢与混凝土之间的滑移效应，建立简化计算模型，并在辞基础上，提出混凝土支座开裂区的长度以及预应力筋内的筋内增量的计算公式。
给出两跨预应力连续组合梁跨中扰度的计算图表。
分析结果表明，两跨预应力连续组合梁变形计算公式计算正常使用极限状态预应力筋的内力值精度提高，不考虑预应力筋内力增量的变形计算值较实验值偏大，考虑预应力筋内力增量的变形计算值得精度有明显提高，与实验结果吻合较好，可供工程设计参考。
最后在两跨预应力连续组合梁变形计算公式的基础上提出预应力连续组合梁变形计算的通用方法引言：普通钢一混凝土连续组合梁由于中支座处混凝土过早开裂，刚度下降，当跨度或荷载较大时，变形和裂缝宽度可能无法满足正常使用极限状态的要求。
试验研究表明，使用预应力技术能较好地解决上述问题，同时还可增大梁的弹性工作范围，充分利用材料性能，从而降低结构高度、减轻自重、减小地震用，增加强度储备，延长使用期限。
在我国，组合的研究起步较晚，对于预应力钢一混凝土连续组梁更是缺乏系统的研究，本文以文献的试验结果为基础，参考了史纲Ⅲ、周安⋯以及段建中提出的变形计算方法，以结构力学的力法为主要分析手段，在聂建国提出的普通连续组合梁计算模型的基础上，提出了一种较为准确实用的预应力钢一混凝土连续组合梁在正常使用极限状态下的变形计算方法，供工程实践参考。
1计算模型预应力钢-混凝土连续组合梁按布筋形式不同，可分为直线布筋和折线布筋，按预应力筋的位置不同，可分体内预应力和体外预应力，其中直线布筋是折线布筋的特例(预应力筋折线处转角为零时即为直线布筋)，而体内预应力和体外预应力的变形分析方法在本文中没有本质的区别，因此本文以折线布筋的预应力两跨连续组合梁作为研究对象，如图l所示，计算方法及结果适用于不同类型的预应力连续组合梁。
C图，两跨预应力连续组合梁受力简图预应力钢一混凝土连续组合梁的变形计算模型如图2所示，图中m表示集中力(外荷载以及预应力筋等效荷载)作用点到相邻支座的距离和单跨跨度的比值，n表示中支座混凝土开裂区的单侧长度和单跨跨度的比值。
预应力混凝土连续梁毕业设计(含外文翻译)
石家庄铁道大学毕业设计（20+40+20）m预应力混凝土连续梁结构设计The Construction Design of the (20+40+20)m Prestressed concrete continuous beam2012 届高等技术学院专业道路桥梁工程技术学号20095116学生姓名 1 2 3指导教师 2 2完成日期2012年5月28日毕业设计任务书毕业设计开题报告摘要本设计主要是关于公路预应力混凝土连续梁桥上部结构的设计。
设计跨度(20+40+20)m。
本设计采用国内著名的有限元分析软件——迈达斯计算,全桥共分40个单元，41个截面，两个施工阶段。
因为连续梁的内力与其施工方法密切相关，本设计采用满堂支架法施工。
这种施工方法操作比较简单，相比其他方法从经济效益上讲也比其他方法更有优势，而且施工质量易得到保证。
计算过程中由于涉及到大量的数字运算，采用手算比较繁琐，并且准确性得不到保证，因此采用计算机辅助设计。
设计中使用了迈达斯来计算内力,并且初步估算配筋量和进行初步验算。
但为了提高设计可靠性，最终还会通过以Excel电子表格计算、AutoCAD辅助软件进行手算，使自己的设计能力有较大的提升。
关键词：预应力混凝土连续梁桥; 迈达斯; 满堂支架法ABSTRACTThis graduate design is mainly about the design of the superstructure of the road prestressed concrete continuous bridge. The span of the bridge is 20m+40m+20m.This design adopts the domestic famous analytical software—MIDAS.The bridge is divided totally into 40units、41 sections and 2 construction stages. Because of the internal force of the continuous girder bridge relating to the method of construction closely, the method of construction of this design adopts the full scaffold construction method. Compared with other methods, this method is quite easy to construct and has economic superiority and the quantity of this construction also could get the assurance easily.Because this design involving a great deal of numerical calculation, it's too tedious to work by hand and the accuracy assuranced hardly. So it restores to CAD. Many bridge specialized software are applied, such as MIDAS applied in calculation of internal forces. and the initial estimate amount of reinforcing steel and initial checking. However, in order to improve design reliability, this will eventually be calculated by the Excel, AutoCAD and other auxiliary software by hand, developing design capabilities with a great improvement at the same time.Key word: Prestressed Concrete Continuous Bridge, MIDAS , Full Scaffold Construction目录第1章绪论 (1)1.1引言 (1)1.2预应力混凝土连续梁桥的发展 (1)1.2.1 国内外预应力混凝土连续梁桥的发展状况 (1)1.2.2预应力混凝土结构的特点 (3)第2章桥梁的总体设计概况 (4)2.1设计基本资料 (4)2.1.1总体设计 (4)2.1.2 主要技术标准 (4)2.1.3 主要材料 (4)2.1.4 设计依据 (4)2.2桥型及纵横断面布置 (5)2.2.1桥型布置及孔径划分 (5)2.2.2截面形式与截面尺寸 (5)第3章模型建立及结果分析 (7)3.1MIDAS的建模说明 (7)3.1.1 MIDAS的介绍 (7)3.1.2 MIDAS的建模步骤 (7)3.2恒载内力计算 (11)3.2.1恒载内力计算 (11)3.2.2活载内力计算 (12)3.2.3钢束的布置与计算 (14)第4章预应力损失及有效应力的计算 (21)4.1预应力损失的计算 (21)4.1.1摩阻损失 (21)4.1.2锚具变形损失 (22)4.1.3混凝土的弹性压缩 (22)4.1.4钢束松弛损失 (22)4.1.5收缩徐变损失 (23)4.2有效预应力的计算 (23)第5章预加力产生的次内力及内力组合 (25)5.1原理 (25)5.2计算方法 (26)5.2.1等效荷载法 (26)第6章内力组合 (27)6.1承载能力极限状态下的效应组合 (27)6.2正常使用极限状态下的效应组合 (32)第7章主梁截面验算 (40)7.1正截面抗弯承载力验算 (40)7.2持久状况正常使用极限状态应力验算 (41)7.2.1 正截面抗裂验算（法向拉应力） (41)7.2.2 斜截面抗裂验算（主拉应力） (43)7.2.3 使用阶段预应力混凝土受压区混凝土最大压应力验算 (44)7.2.4 预应力钢筋中的拉应力验算 (45)7.2.5 混凝土的主压应力验算 (45)7.3短暂状况预应力混凝土受弯构件应力验算 (45)第8章结束语 (47)参考文献 (48)致谢 (49)附录 (50)外文翻译 (50)第1章绪论1.1引言随着经济建设的迅速发展，我国城市交通的桥梁建设也进入迅速发展时期。
土木工程英文外文文献翻译分析预应力混凝土连续梁毕业设计[管理资料]
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分析预应力混凝土连续梁1 绪论这次会议是专门讨论结构分析的发展，而不是讨论材料强度，但对材料的认识并用适当的技术分析结构的组成，有助于有效地利用预应力混凝土。
预应力混凝土结构的设计通常是留给专家；粗心将会导致错误或花费更多时间用各种方法寻求解决的方案。
有一些根本性的分歧在预应力混凝土和其他材料之间。
在没有作用荷载下结构依然是受力；可行的解决方案是有限的，在超静定结构，缆索外形的改变会引起不同的自应力，所有这些要素都是受到徐变和温度效应的影响。
如何判别这些问题和如何解决他们呢？自从在十九世纪末Hennebique对钢筋混凝土进行了研究（库萨克1984年），它表明了钢筋和混凝土能更有效地结合起来，如果钢先预制然后把混凝土灌进去。
开裂可以减少，如果可以很好的粘结在一起，这将增加刚度和提高耐久性。
早期尝试，所有失败的原因是由于初始预应力很快消失，留下的结构必须具备一定的承受能力；关于这些情况Leonhardt和Abeles已做出了尝试。
这是Freyssinet对三座桥梁的观察结果，它坐落在维希附近的Allier河上，1927年完成。
用的是预应力混凝土（ Freyssinet 1956年）。
只有Boutiron这座桥在二战中保留下来（图1 ）。
迄今，它一直假定混凝土的杨氏模量仍然是固定的，但他承认说由于变形的存在，这也解释为何在早期的检测预应力已经损失。
Freyssinet （图2 ）因为高强度钢筋已予使用，所以发生徐变后仍然残留有一些预应力，而且同时使用了高质量的混凝土，因此这可减少总体的徐变。
关于Freyssinet的早期预应力混凝土研究是被写在其他地方。
Figure1:Boutiron Bridge，Vic h yFigure 2: Eugen Freyssinet大约在同一时间，这个工作也在英格兰的BRE实验室进行着（（格兰维尔1930年）和（ 1933 ））。
徐变的发现将归功于谁，受到了争论，但Freyssinet对预应力混凝土的研究和成功的应用是大家都公认的。
预应力混凝土桥梁悬臂浇筑的线形控制-毕业论文外文翻译
英文原文及翻译Linear Control In Cantilever Casting of Prestressed ConcreteBridge[Abstract]Symmetric cantilever construction method does not affect the bridge during the construction of shipping or travel, and make full use of the negative moment capacity of prestressed concrete to withstand the strong features, improved ability to cross the bridge, cantilever construction method focuses on linear control . In this paper, double-track highway bridge Nanjiang prestressed concrete continuous girder bridge as an example, the cantilever suspended scaffolding construction, closure to control the construction process such as linear methods and measures.[Key words] Cantilever construction; deflection; Closure; linear controlI.Project OverviewDouble-track road bridge in southern Bohai Bank Haihe River estuary, the existing South Bridge and the Southern Xinjiang Railway Bridge north, west and Jingu line across Beach Boulevard overpass connecting east and southern ports, the main road South road connecting the bridge and the existing South Bridge is the vehicle out of the important southern port access road.Double-track main highway bridge in South Bridge 2 (48.6 m +3 × 64 m + 48.6 m) tapered prestressed concrete continuous box girder. The total bridge width 26.5 m, and each piece box for the independent web single box single straight section, the main fulcrum of the beam across the high 4 m, cross the beam of high 2 m, by the end of the second parabola beam, box beam from the roof 2% formation of one-way cross-slope, high beams are a bridge height of the lateral web edge.II. Linear Control of CantileverCantilever construction (also called balanced cantilever construction) is completed piers, along the direction of two adjacent span symmetrically piecewise construction of a balanced approach. As the cantilever beam construction within the negative moment, to be on the concrete bridge beams prestressed paragraph by paragraph, the upper edge so that it has completed the beam section with links into the whole structural system and the conversion by cross-fold, eventually form a bridge structure.As the bridge construction and operation of the stress state when the stress state similar to warrant the need for construction materials increased over the amount. As the construction of state (working load, prestress loss, concrete shrinkage and creep, temperature, humidity, time, etc.), parameter selection (material properties, section properties, etc.) and structure of the calculation model, and site conditions are different; same time, the structure of difficult to accurately determine the nonlinear deformation; construction of the variability of the materials used and other factors, makes the construction process, the actual state deviates from the design structure of the desired ideal state. Therefore, the bridge structure during construction must be the actual response (elevation, line, main beam stress, etc.) for the strict construction control.A. 0 # block constructionHanging is the use of the box section has been poured as a strong point, and so on through truss girder system, the end of cantilever casting mold system, so people No.0 is to create a working platform.Box at the pier beam No.0 binding sites are complex, embedded parts, steel, all steel beams and channels to the PC, anchorage-intensive staggered, vertical and horizontal beam surface has slope face and cross section to be closely linked using a casting process, concrete square about 237.8 square meters. Full Support cap use of erection, stent placement No.0.0 # initial segment of the construction block is the elevation of the structure formed by the elevation of its pre-modification, deformation and foundation support settlement thrown high, and bearing high-pressure deformation cast composition. Among them, the stent deformation and foundation settlement Parabolic the greatest impact on the elevation. Therefore, the initial segment of stent stiffness stronger foundation should be strong, to reduce the structural alignment of the initial error.B. Deflection Control in Construction0 # block concrete pouring and tension on the bearings were temporary measures with fixed after the assembly in the block No. 0 Basket, symmetrical piecewise Cantilever Block 1 to 7. Finally, in cross-section of the construction carried out in close. Span continuous multi-span cantilever bridge construction is one of the most important tasks deflection calculation and control. Box Girder Bridge linear control to keep the whole key to the design requirements.Continuous beam bridge construction cantilever deflection is comprised of: the main pier section Cantilever deflection when the T structure system; system converted each segment into a continuous system of bridge deflection and after the dead load,live load and the system of post-shrinkage and creep caused by deflection; Cradle system deflection under load.Since the calculation involves the calculation of deflection schema, the temporary load simulation, the simulation of concrete pouring process, prestressed position and tension of the simulation, post-dead load, live load, impact and long creep effects, the deflection accurate calculation of extremely complex reality. Thus, Cantilever construction before the concrete mix according to the sample, measure the elastic modulus of concrete, concrete shrinkage coefficient of bulk density and other parameters, to repeatedly check calculations and compared with the design data to find problems. In the construction of the control process should also be amended according to the measured elevation data structure of parameters.C. Factors affecting the control of deflection1) block set piece weight variation degree of the quality of block pieces primarily by cross-section dimensions and concrete bulk density caused by bias.2) effective prestress prestressed here effectively means Prestressed after transient loss (prestressed pipeline positioning, tension, pipe friction) the completion of the PC.3) The elastic modulus of concrete elastic modulus is the physical parameters of high-strength grade concrete elastic modulus of growth often lags behind the growth of concrete strength, so when the box block piece construction period is short, on the impact of the deflection is Great.4) Creep Creep is the main beam deflection of the main factors, concrete shrinkage and creep need three years to complete, according to environmental conditions on site concrete shrinkage and creep test results are concrete creep ε t curve smoothing first observation, and then joined the integrated creep coefficient of variation, coefficient of variation of repeated re-adjustment of a spreadsheet can be adjusted to determine the amount of creep parameters.5) Hanging Basket System deformation deformation Cantilever for continuous bridge plays an important role. Hanging Basket general reference to pre-distortion system pressure test data, and specific predictions have been built in accordance with the deformation of beam construction to analysis, which can be speculated to be built pre-cast beams Hanging high. Basket deformation prediction error will directly lead to the absolute segment elevation error and relative error.D. Cantilever construction of each segment elevation controlCantilever construction of each segment elevation controls, including three key conditions: Cradle forward positioning Elevation (Elevation of legislation); elevation after concrete pouring; prestressed tension after the elevation.To correctly reflect the changes in bridge construction, the beam bottom elevation as the construction of control objectives. Each segment monitoring points from the beam deflection measured points by the end of web lead to the deck. Hanging by beam elevation positioning the end of segment to be poured the forefront of cross section measurement point positioning, pouring concrete, after completion, by measuring the beam embedded in the reinforced top of the head corresponding to the beam elevation with the bottom elevation at this time, the end of beam Top of the measuring point with the beam elevation relationship, so that the beam has been poured beam segment elevation by the end of the top level of the measurement beam feedback out.E. Cantilever Beam DeflectionIn order to offset the construction for a variety of deformation (deflection) in the construction process, the legislation does not mean Elevation of the bridge design is completed the level, always set a certain camber.After the concrete pouring of the elevation of each control point, mainly for checking the state of existing structures in order to correct the calculation of building structure and the forecast level to be cast segmental parameters, adjust and optimize bridge alignment, are to be poured Festival construction segment elevation.Post-tensioning prestressed structure control of elevation measurements, measured after the loss of prestress prestressed arch generated on the purpose built structure on the state of the check in order to amend forecast to be poured segment elevation; were measured with the use of Feedback calculated structural parameters of the differences, to understand whether there stressed the value of deviation, prestressed linear modeling is appropriate, loss of prestress whether the estimate was correct and that the decision whether to revise the theory of pre-tension value.F.Box beam girder stress and strain analysisMain beam in the cantilever casting process by considering the control section of statically determinate structure, the system converted the structure into account by indeterminate control section, generally selected No.0 root, L / 4, L / 2, 3L / 4 and Closure Office, as control section, in these sections within the embedded steel string sensor, for strain measurement. Steel wire sensors embedded in concrete, the axial force at the natural frequency of steel chord changes.G. Construction of ClosureCantilever construction closure is an important part of system transformation, closure stress state construction must meet the design requirements and to maintain beam alignment, control of Closure of the construction error. Closure at both ends of cantilever beam section of temperature change may have vertical stretch so close I pitch change, leading to closure during solidification of concrete beams under paragraph tension or compression stress generated ultra crack. Need to close the side of the pier into a temporary anchor bearing activities to reduce the impact. Meanwhile, former should be pouring concrete at both ends of cantilever closure temporary connections, temporary form a rigid connection, the protection of ClosureConcrete complete until closure to a certain section of concrete curing, and prestressed and cantilever strength form a whole.1) The closure orderAccording to design requirements, according to the first side of the bridge span, plays in the cross, the cross-order closure2) Elevation control of ClosureClosure construction elevation is based on some segments have been cast molding, linear and disconnecting, with minimum deviation principle for elevation determined. As the construction segment elevation error, the scheduled construction of Closure will be constant elevation changes, until the close.III. ConclusionThis double-track road to South Bridge, for example, introduced prestressed concrete cantilever casting of linear control deflection and control. Double-track construction of highway bridges in the South, by careful organization do a good job controlling the successful completion of the process of full bridge vertical closure, closure section is about the average height difference in 8mm, the maximum height difference of 18cm, 3cm to meet the specification requirements. For large span prestressed concrete bridge construction to the stress and deflection on the control of the dual entry.References:[1] Zhou Mi, a Song Fan, ZHAO Xiao-star. Cantilever Concrete Bridge Construction Control [J]. Chang'an University (Natural Science), 2005[2] Preventing Global Warming. Prestressed concrete continuous beams and rigid frame cantilever construction technique [J]. Construction, 2004[3] Zhou Yajun. Cantilever Linear Continuous Prestressed Concrete Box Girder Construction Control [J]. China Exploration Engineering, 2005[4] Yu Hui, Cao Mingxu. Cantilever Prestressed Concrete Continuous Beam Bridge Deflection[J]. Modern Transportation Technology, 2005[5] You Jizhong. Cantilever bridge linear control of continuous casting [J]. Inner Mongolia Highway and Transport, 2006预应力混凝土桥梁悬臂浇筑的线形控制［摘要］对称悬臂的施工方法在施工期间不影响桥下通航或行车，而且充分利用了预应力混凝土承受负弯矩能力强的特点，提高了桥梁的跨越能力，悬臂施工法的重点是线形控制。
外文文献翻译原文(大型水工预应力渡槽的温度应力分析研究)
外文参考文献Thermal Stress Analysis of A Hydraulic aqueduct PrestressedG。
P.Harrison and H.W.Whittington［Abstract ] Large scale aqueduct is adopted as a optional plan for the crossing yellowriver structure of the project of transferring water from the South to the North. Prestressed reinforced concrete structure is the best choice. The designed aqueduct span is 50m. Self—weight of the upper part of the structure for one span is 15.93MN，and corresponding weight of the water in one span is19.85MN。
The stress in every part of the structure varies largely. As the project is located in the area that has large temperature variation, thethermal stress produced in the structure by the variation of the surrounding temperature isa big problem. In this paper，the thermal stress in the aqueduct is studied for all possible conditions，and suggestions to guarantee the safety of the aqueduct under possible large temperature variation is made。
土木外文文献及译文简支梁布局
本科毕业设计外文文献及译文文献、资料题目：Simple Beam Layout文献、资料来源：网络文献、资料发表（出版）日期：院（部）：治理工程学院专业：信息治理与信息系统班级：信管082姓名：闻龙学号：26指导教师：郭兵姜卫杰翻译日期：外文文献：Simple Beam LayoutThe layout of a simple prestressed-concrete beam is controlled by two critical sections: the maximum moment and the end sections. After these sections are designed, intermediate ones can often be determined by inspection but should be separately investigated when necessary. The maximum moment section is controlled by two loading stages, the initial stage at transfer with minimum moment MG acting on the beam and the working-load stage with maximum design moment MT. The end sections are controlled by area required for share resistance, bearing plates,anchorage spacings, and jacking clearances. All intermediate sections are designed by one or more of the above requirements, depending on their respective distances from the above controlling sections. A common arrangement for posttensioned members is to employ some shape, such as I or T, for the maximum moment section and to round it out into a simple rectangular shape near the ends. This is commonly referred to as the end block for posttensioned members. For pretensioned members, produced on a long line process, a uniform I, double-T, or cored section is employed throughout, in order to facilitate production. The design for individual sections having been explained in Chapters 5, 6, and 7,the general cable layout of simple beams will now be discussed.The layout of a beam can be adjusted by varying both the concrete and the steel. The section of concrete can be varied as to its height, width, shape, and the curvature of its soffit or extrados. The steel can be varied occasionally in its area but mostly in its position relative to the centroidal axis of concrete. By adjusting these variables, many combinations of layout are possible to suit different loading conditions. This is quite different from the design of reinforced-concrete beams, where the usual layout is either a uniform rectangular section or a uniform T-section and the position of steel is always as near the bottom fibers as is possible.Consider first the pretensioned beams, Fig. straight cables are preferred, since they can be more easily tensioned between two abutments. Let us start with a straight cable in a straight beam of uniform section, (a).This is simple as far as form and workmanship are concened, But such a section cannot often be economically designed, because of the conflicting requirements of the midspan and end sections. At the maximum moment section generally occurring at midspan, it is best to place the cable as near the bottom as possible in order to provide the maximum lever arm for the internal resisting moment. When the MG at midspan is appreciable, it is possible to place the c. g. s. much below the kern without producing tension in the top fibers at transfer. The end section, however, presents an entirely different set of requirements. Since there is no external moment at the end, it is best to arrange the tendons so that the c. g. s. will coincide with the c. g. c. at the end section, so as to obtain a uniform stress distribution. In any case, it is necessary to placethe c. g. s. within the kern if tensile stresses are not permitted at the ends, and not too far outside the kern to avoid tension stress in excess of allowable values.It is not possible to meet the conflicting requirements of both the midspan and the end sections by a layout such as ( a ). For example, if the c. g. s. is located all along the lower kern point, which is the lowest point permitted by the end section, a satisfactory lever arm is not yet attained for the internal resisting moment at midspan. If the c. g. s. is located below the kern, a bigger lever arm is obtained for resisting the moment at midspan, but stress distribution will be more unfavorable at the ends. Besides, too much camber may result from such a layout, since the entire length of the beam is subjected to negative bending due to prestress. In spite of these objections, this simple arrangement is often used, especially for short spans.Fig 8-7. Layouts for pretensioned beams.For a uniform concrete section and a straight cable, it is possible to get a more desirable layout than ( a ) by simple varying the soffit of the beam, as in Fig. 8-7( b ) and ( c ); ( b ) has a bent soffit, while ( c ) has a curved one. For both layouts, the c. g. s. at midspan can be depressed as low as desired, while that at the ends can be kept near the c. g. c. If the soffit can be varied at will, it is possible to obtain a curvature that will best fit the given loading condition; for example, a parabolic soffit will suit a uniform loading. While these two layouts are efficient in resisting moment and favorable in stress distribution, they possess three disadvantages. First, the formwork is more complicated than in ( a ). Second, the curved or bent soffit is often impractical in a structure, for architectural or functional reasons. Third, they cannot be easily produced on a long-line pretensioning bed.When it is possible to vary the extrados of concrete, a layout like Fig. 8-7( d ) or ( e ) can be advantageously employed. These will give a favorable height at midspan, where it is most needed, and yet yield a concentric or nearly concentric prestress at end section. Since the depth is reduced for the end sections, they must be checked for share resistance. For ( d ), it should also be noted that the critical section may not be at midspan but rather at some point away from it where the depth has decreasd appreciably while the external moment is still near the maximum. Beam ( d ), however, is simple in formwork than ( e ), which has a curved extrados.Most pretensioning plants in the United States have buried anchors along the stressing beds so that the tendons for a pretensioned beam can be bent, Fig. 8-7( f ) and ( g ). It may be economical to do so ,if the beam has to be of straight and uniform section, and if the MG is heavy enough to warrant such additional expense of bending. Means must be provided to reduce the frictional loss of prestress produced by the bending of the tendons. For example, the tendons may be tensioned first from the ends and then bent at the harping points.It is evident from the above discussion that many different layouts are possible. Only some basic forms are described here, the variations and combinations being left to the discretion of the designer. The correct layout for each structure will depend upon the local conditions and the practical requirements as well as upon theoretical considerations.Most of the layouts for pretensioned beams can be used for posttensioned ones as well. But, for posttensioned beams, Fig. 8-8, it is not necessary to keep the tendons straight, since slightly bent or curved tendons can be as easily tensioned as straight ones. Thus, for a beam of straight and uniform section, the tendons are very often curved as in Fig. 8-8( a ). Curving the tendons will permit favorable positions of c. g. s. to be obtained at both the end and midspan sections, and other points as well.Fig 8-8. Layouts for posttensioned beams.A combination of curved or bent tendons with curved or bent soffits is frequently used, Fig. 8-8( b ), when straight soffits are not required. This will permit a smaller curvature in the tendons, thus reducing the friction. Curved or bent cables are also combined with beams of variable depth, as in ( c ). Combinations of straight and curved tendons are sometimes found convenient, as in ( d ).Variable steel area along the length of a beam is occasionally preferred. This calls for special design of the beam and involves details which may offset its economy in weight of steel. In Fig. 8-8( e ), some cables are bent upward and anchored at top flanges. In ( f ), some cables arestopped part way in the bottom flange. These arrangements will save some steel but may not be justified unless the saving is considerable as for very long spans carrying heavy loads.8-3 Cable ProfilesWe stated in the previous section that the layout of simple beams is controlled by the maximum moment and end sections so that, after these two sections are designed, other sections can often be determined by inspection. It sometimes happens, however, that intermediate points along the beam may also be critical, and in many instances it would be desirable to determine the permissible and desirable profile for the tendons. To do this, a limiting zone for the location of c.g. s. is first obtained, then the tendons are arranged so that their centroid will lie within the zone.The method described here is intended for simple beams, but it also serves as an introduction to the solution of more complicated layouts, such as cantilever and continuous spans, where cable location cannot be easily determined by inspection. The method is a graphical one; giving the limiting zone within which the c. g. s. must pass in order that no tensile stresses will be produced. Compressive stresses in concrete are not checked by this method. It is assumed that the layout of the concrete sections and the area of prestressing steel have already been determined. Only the profile of the c. g. s. is to be located.Referring to Fig . 8-9, having determined the layout of concrete sections, we proceed to compute their kern points, thus yielding two kern lines, one top and one bottom, ( c ) . Note that for variable sections, these kern lines would be curved, although for convenience they are shown straight in the figure representing a beam with uniform cross section.For a beam loaded as shown in ( a ), the minimum and maximum moment diagrams for the girder load and for the total working load respectively are marked as MG and MT in ( b ). In order that, under the working load, the center of pressure, the C-line, will not fall above the top kern line, it is evident that the c. g. s. must be located below the top kern at least a distancea1=MT/F (8-1)Fig 8-9. Location of limiting zone for c. g. s.If the c. g. s. falls above that upper limit at any point, then the C-line corresponding to moment MT and prestress F will fall above the top kern, resulting in tension in the bottom fiber.Similarly, in order that the C-line will not fall below the bottom kern line, the c. g. s. line must not be positioned below the bottom kern by a distance greater than which gives the lower limit for the location of c. g. s. If the c. g. s. is positioned above that lower limit, it is seen that the C-line will be above the bottom kern and there will be no tension in the top fiber under the girder load and initial prestress F0.Thus, it becomes clear that the limiting zone for c. g. s. is given by the shaded area in Fig.8-9( c ), in order that no tension will exist both under the girder load and under the working load. The individual tendons, however, may be placed in any position so long as the c. g. s. of all the cables remains within the limiting zone.The position and width of the limiting zone are often an indication of the adequacy and economy of design, Fig. 8-10. If some portion of the upper limit falls outside or too near the bottom fiber, in ( a ), either the prestress F or the depth of beam at that portion should be increased. On the other hand, if it falls too far above the bottom fiber, in ( b ), either the prestress or the beam depth can be reduced. If the lower limit crosses the upper limit, in ( C ), it means that no zone is available for the location of c. g. s. , and either the prestress F or the beam depth must be increased or the girder moment must be increased to depress the lower limit if that can be done. On the other hand, as will be discussed later, the case shown in Fig. ( c ) may be very satisfactory when are allowing tensile stress in concrete.Fig 8-10. Undesirable positions for c. g. s. zone limits.中文译文：简支梁布局一个简单的预应力混凝土梁由两个危险截面操纵：最大弯矩截面和端截面。
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毕业设计（论文）外文文献翻译文献、资料题目：分析预应力混凝土连续梁文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14外文文献翻译原文Analysis of Con tin uous Prestressed Concrete BeamsChris BurgoyneMarch 26, 20051、IntroductionThis conference is devoted to the development of structural analysis rather than the strength of materials, but the effective use of prestressed concrete relies on an appropriate combination of structural analysis techniques with knowledge of the material behaviour. Design of prestressed concrete structures is usually left to specialists; the unwary will either make mistakes or spend inordinate time trying to extract a solution from the various equations.There are a number of fundamental differences between the behaviour of prestressed concrete and that of other materials. Structures are not unstressed when unloaded; the design space of feasible solutions is totally bounded；in hyperstatic structures, various states of self-stress can be induced by altering the cable profile, and all of these factors get influenced by creep and thermal effects. How were these problems recognised and how have they been tackled?Ever since the development of reinforced concrete by Hennebique at the end of the 19th century (Cusack 1984), it was recognised that steel and concrete could be more effectively combined if the steel was pretensioned, putting the concrete into compression. Cracking could be reduced, if not prevented altogether, which would increase stiffness and improve durability. Early attempts all failed because the initial prestress soon vanished, leaving the structure to be- have as though it was reinforced; good descriptions of these attempts are given by Leonhardt (1964) and Abeles (1964).It was Freyssineti’s observations of the sagging of the shallow arches on three bridges that he had just completed in 1927 over the River Allier near Vichy which led directly to prestressed concrete (Freyssinet 1956). Only the bridge at Boutiron survived WWII (Fig 1). Hitherto, it had been assumed that concrete had a Young’s modulus which remained fixed, but he recognised that the de- ferred strains due to creep explained why the prestress had been lost in the early trials. Freyssinet (Fig. 2) also correctly reasoned that high tensile steel had to be used, so that some prestress would remain after the creep had occurred, and also2that high quality concrete should be used, since this minimised the total amount of creep. The history of Freyssineti’s early prestressed concrete work is written elsewhereFigure1:Boutiron Bridge,Vic h yFigure 2: Eugen FreyssinetAt about the same time work was underway on creep at the BRE laboratory in England ((Glanville 1930) and (1933)). It is debatable which man should be given credit for the discovery of creep but Freyssinet clearly gets the credit for successfully using the knowledge to prestress concrete.There are still problems associated with understanding how prestressed concrete works, partly because there is more than one way of thinking about it. These different philosophies are to some extent contradictory, and certainly confusing to the young engineer. It is also reflected, to a certain extent, in the various codes of practice.Permissible stress design philosophy sees prestressed concrete as a way of avoiding cracking by eliminating tensile stresses; the objective is for sufficient compression to remain after creep losses. Untensionedreinforcement, which attracts prestress due to creep, is anathema. This philosophy derives directly from Freyssinet’s logic and is prima rily a working stress concept.Ultimate strength philosophy sees prestressing as a way of utilising high tensile steel as reinforcement. High strength steels have high elastic strain capacity, which could not be utilised when used as reinforcement; if the steel is pretensioned, much of that strain capacity is taken out before bonding the steel to the concrete. Structures designed this way are normally designed to be in compression everywhere under permanent loads, but allowed to crack under high live load. The idea derives directly from the work of Dischinger (1936) and his work on the bridge at Aue in 1939 (Schonberg and Fichter 1939), as well as that of Finsterwalder (1939). It is primarily an ultimate load concept. The idea of partial prestressing derives from these ideas.The Load-Balancing philosophy, introduced by T.Y. Lin, uses prestressing to counter the effect of the permanent loads (Lin 1963). The sag of the cables causes an upward force on the beam, which counteracts the load on the beam. Clearly, only one load can be balanced, but if this is taken as the total dead weight, then under that load the beam will perceive only the net axial prestress and will have no tendency to creep up or down.These three philosophies all have their champions, and heated debates take place between them as to which is the most fundamental.2、Section designFrom the outset it was recognised that prestressed concrete has to be checked at both the working load and the ultimate load. For steel structures, and those made from reinforced concrete, there is a fairly direct relationship between the load capacity under an allowable stress design, and that at the ultimate load under an ultimate strength design. Older codes were based on permissible stresses at the working load; new codes use moment capacities at the ultimate load. Different load factors are used in the two codes, but a structure which passes one code is likely to be acceptable under the other.4For prestressed concrete, those ideas do not hold, since the structure is highly stressed, even when unloaded. A small increase of load can cause some stress limits to be breached, while a large increase in load might be needed to cross other limits. The designer has considerable freedom to vary both the working load and ultimate load capacities independently; both need to be checked.A designer normally has to check the tensile and compressive stresses, in both the top and bottom fibre of the section, for every load case. The critical sections are normally, but not always, the mid-span and the sections over piers but other sections may become critical ，when the cable profile has to be determined.The stresses at any position are made up of three components, one of which normally has a different sign from the other two; consistency of sign convention is essential.If P is the prestressing force and e its eccentricity, A and Z are the area of the cross-section and its elastic section modulus, while M is the applied moment, then where ft and fc are the permissible stresses in tension and compression.c e t f ZM Z P A P f ≤-+≤Thus, for any combination of P and M , the designer already has four in- equalities to deal with.The prestressing force differs over time, due to creep losses, and a designer is6usually faced with at least three combinations of prestressing force and moment;• the applied moment at the time the prestress is first applied, before creep losses occur,• the maximum applied moment after creep losses, and• the minimum applied moment after creep losses.Figure 4: Gustave MagnelOther combinations may be needed in more complex cases. There are at least twelve inequalities that have to be satisfied at any cross-section, but since an I-section can be defined by six variables, and two are needed to define the prestress, the problem is over-specified and it is not immediately obvious which conditions are superfluous. In the hands of inexperienced engineers, the design process can be very long-winded. However, it is possible to separate out the design of the cross-section from the design of the prestress. By considering pairs of stress limits on the same fibre, but for different load cases, the effects of the prestress can be eliminated, leaving expressions of the form:rangestress e Perm issibl Range Mom entZ These inequalities, which can be evaluated exhaustively with little difficulty, allow the minimum size of the cross-section to be determined.Once a suitable cross-section has been found, the prestress can be designed using a construction due to Magnel (Fig.4). The stress limits can all be rearranged into the form:()M fZ PA Z e ++-≤1 By plotting these on a diagram of eccentricity versus the reciprocal of the prestressing force, a series of bound lines will be formed. Provided the inequalities (2) are satisfied, these bound lines will always leave a zone showing all feasible combinations of P and e. The most economical design, using the minimum prestress, usually lies on the right hand side of the diagram, where the design is limited by the permissible tensile stresses.Plotting the eccentricity on the vertical axis allows direct comparison with the crosssection, as shown in Fig. 5. Inequalities (3) make no reference to the physical dimensions of the structure, but these practical cover limits can be shown as wellA good designer knows how changes to the design and the loadings alter the Magnel diagram. Changing both the maximum andminimum bending moments, but keeping the range the same, raises and lowers the feasible region. If the moments become more sagging the feasible region gets lower in the beam.In general, as spans increase, the dead load moments increase in proportion to the live load. A stage will be reached where the economic point (A on Fig.5) moves outside the physical limits of the beam; Guyon (1951a) denoted the limiting condition as the critical span. Shorter spans will be governed by tensile stresses in the two extreme fibres, while longer spans will be governed by the limiting eccentricity and tensile stresses in the bottom fibre. However, it does not take a large increase in moment ，at which point compressive stresses will govern in the bottom fibre under maximum moment.Only when much longer spans are required, and the feasible region moves as far down as possible, does the structure become governed by compressive stresses in both fibres.3、Continuous beamsThe design of statically determinate beams is relatively straightforward; the engineer can work on the basis of the design of individual cross-sections, as outlined above. A number of complications arise when the structure is indeterminate which means that the designer has to consider, not only a critical section,but also the behaviour of the beam as a whole. These are due to the interaction of a number of factors, such as Creep, Temperature effects and Construction Sequence effects. It is the development of these ideas which8forms the core of this paper. The problems of continuity were addressed at a conference in London (Andrew and Witt 1951). The basic principles, and nomenclature, were already in use, but to modern eyes concentration on hand analysis techniques was unusual, and one of the principle concerns seems to have been the difficulty of estimating losses of prestressing force.3.1 Secondary MomentsA prestressing cable in a beam causes the structure to deflect. Unlike the statically determinate beam, where this motion is unrestrained, the movement causes a redistribution of the support reactions which in turn induces additional moments. These are often termed Secondary Moments, but they are not always small, or Parasitic Moments, but they are not always bad.Freyssinet’s bridge across the Marne at Luzancy, started in 1941 but not completed until 1946, is often thought of as a simply supported beam, but it was actually built as a two-hinged arch (Harris 1986), with support reactions adjusted by means of flat jacks and wedges which were later grouted-in (Fig.6). The same principles were applied in the later and larger beams built over the same river.Magnel built the first indeterminate beam bridge at Sclayn, in Belgium (Fig.7) in 1946. The cables are virtually straight, but he adjusted the deck profile so that the cables were close to the soffit near mid-span. Even with straight cables the sagging secondary momentsare large; about 50% of the hogging moment at the central support caused by dead and live load.The secondary moments cannot be found until the profile is known but the cable。