桥梁毕业设计外文翻译

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毕设外文翻译是什么意思(两篇)

毕设外文翻译是什么意思(两篇)

引言概述:在现代高等教育中,毕业设计(或称为毕业论文、学士论文等)是学生完成学业的重要环节。

而对于一些特定的专业,例如翻译专业,有时候还需要完成外文翻译这一项任务。

本文将探讨毕设外文翻译的意义和目的,以及为什么对翻译专业的学生而言这一任务极其重要。

正文内容:1.提高翻译能力和技巧外文翻译是一项对翻译专业学生而言十分重要的任务,通过进行外文翻译,学生们可以通过实践提高自己的翻译能力和技巧。

在这个过程中,他们可以学习如何处理不同类型的外文文本,熟悉不同领域的专业术语,并掌握一些常用的翻译技巧和策略。

2.扩展语言和文化知识毕设外文翻译要求学生们对翻译语言的相关知识和背景有一定的了解。

在进行翻译时,学生们需要遵循目标语言的语法规则,并确保所翻译的内容准确、清晰地传达源语言的意义。

通过这一过程,学生们可以进一步扩展自己的语言和文化知识,提高自己的跨文化沟通能力。

3.提供实践机会毕设外文翻译为学生们提供了一个实践的机会,让他们能够将在课堂上所学到的理论知识应用于实际操作中。

通过实践,学生们可以对所学知识的理解更加深入,同时也可以发现并解决实际翻译过程中的问题和挑战。

这对于学生们将来从事翻译工作时具备更好的实践能力和经验具有重要意义。

4.培养翻译专业素养毕设外文翻译要求学生们具备良好的翻译专业素养。

在进行翻译过程中,学生们需要保持专业的态度和责任心,严谨地对待每一个翻译任务。

他们需要学会如何进行翻译质量的评估和控制,以确保最终翻译稿的准确性和流畅性。

这一系列的要求和实践,可以帮助学生们培养出色的翻译专业素养。

5.提升自我学习和研究能力毕设外文翻译要求学生们进行广泛的文献阅读和研究,以便更好地理解所翻译的内容,并找到适当的翻译方法和策略。

在这个过程中,学生们需要培养自己的自主学习和研究能力,提高对学术和专业领域的敏感性,并能够独立思考和解决问题。

这将对学生们未来的学术研究和进一步的职业发展产生积极的影响。

总结:引言概述:毕业设计外文翻译(Thesis Translation)是指在毕业设计过程中,对相关外文文献进行翻译,并将其应用于研究中,以提供理论支持和参考。

土木工程专业毕业设计- 外文翻译

土木工程专业毕业设计- 外文翻译

Structure in Design of ArchitectureAnd Structural Material专业:土木工程学生:指导老师:We have and the architects must deal with the spatial aspect of activity, physical, and symbolic needs in such a way that overall performance integrity is assured. Hence, he or she well wants to think of evolving a building environment as a total system of interacting and space forming subsystems. Is represents a complex challenge, and to meet it the architect will need a hierarchic design process that provides at least three levels of feedback thinking: schematic, preliminary, and final.Such a hierarchy is necessary if he or she is to avoid being confused , at conceptual stages of design thinking ,by the myriad detail issues that can distract attention from more basic considerations .In fact , we can say that an architect’s ability to distinguish the more basic form the more detailed issues is essential to his success as a designer .The object of the schematic feed back level is to generate and evaluate overall site-plan, activity-interaction, and building-configuration options .To do so the architect must be able to focus on the interaction of the basic attributes of the site context, the spatial organization, and the symbolism as determinants of physical form. This means that ,in schematic terms ,the architect may first conceive and model a building design as an organizational abstraction of essential performance-space in teractions.Then he or she may explore the overall space-form implications of the abstraction. As an actual building configuration option begins to emerge, it will be modified to include consideration for basic site conditions.At the schematic stage, it would also be helpful if the designer could visualize his or her options for achieving overall structural integrity and consider the constructive feasibility and economic of his or her scheme .But this will require that the architect and/or a consultant be able to conceptualize total-system structural options in terms of elemental detail .Such overall thinking can be easily fed back to improve the space-form scheme.At the preliminary level, the architect’s emphasis will shift to the elaboration of his or her more promising schematic design options .Here the architect’s structural needs will shift to approximate design of specific subsystem options. At this stage the total structural scheme is developed to a middle level of specificity by focusing on identification and design of major subsystems to the extent that their key geometric, component, and interactive properties are established .Basic subsystem interaction and design conflicts can thus be identified and resolved in the context of total-system objectives. Consultants can play a significant part in this effort; these preliminary-level decisions may also result in feedback that calls for refinement or even major change in schematic concepts.When the designer and the client are satisfied with the feasibility of a design proposal at the preliminary level, it means that the basic problems of overall design are solved and details arenot likely to produce major change .The focus shifts again ,and the design process moves into the final level .At this stage the emphasis will be on the detailed development of all subsystem specifics . Here the role of specialists from various fields, including structural engineering, is much larger, since all detail of the preliminary design must be worked out. Decisions made at this level may produce feedback into Level II that will result in changes. However, if Levels I and II are handled with insight, the relationship between the overall decisions, made at the schematic and preliminary levels, and the specifics of the final level should be such that gross redesign is not in question, Rather, the entire process should be one of moving in an evolutionary fashion from creation and refinement (or modification) of the more general properties of a total-system design concept, to the fleshing out of requisite elements and details.To summarize: At Level I, the architect must first establish, in conceptual terms, the overall space-form feasibility of basic schematic options. At this stage, collaboration with specialists can be helpful, but only if in the form of overall thinking. At Level II, the architect must be able to identify the major subsystem requirements implied by the scheme and substantial their interactive feasibility by approximating key component properties .That is, the properties of major subsystems need be worked out only in sufficient depth to very the inherent compatibility of their basic form-related and behavioral interaction . This will mean a somewhat more specific form of collaboration with specialists then that in level I .At level III ,the architect and the specific form of collaboration with specialists then that providing for all of the elemental design specifics required to produce biddable construction documents .Of course this success comes from the development of the Structural Material.The principal construction materials of earlier times were wood and masonry brick, stone, or tile, and similar materials. The courses or layers were bound together with mortar or bitumen, a tar like substance, or some other binding agent. The Greeks and Romans sometimes used iron rods or claps to strengthen their building. The columns of the Parthenon in Athens, for example, have holes drilled in them for iron bars that have now rusted away. The Romans also used a natural cement called puzzling, made from volcanic ash, that became as hard as stone under water.Both steel and cement, the two most important construction materials of modern times, were introduced in the nineteenth century. Steel, basically an alloy of iron and a small amount of carbon had been made up to that time by a laborious process that restricted it to such special uses as sword blades. After the invention of the Bessemer process in 1856, steel was available in large quantities at low prices. The enormous advantage of steel is its tensile force which, as we have seen, tends to pull apart many materials. New alloys have further, which is a tendency for it to weaken as a result of continual changes in stress.Modern cement, called Portland cement, was invented in 1824. It is a mixture of limestone and clay, which is heated and then ground into a power. It is mixed at or near the construction site with sand, aggregate small stones, crushed rock, or gravel, and water to make concrete. Different proportions of the ingredients produce concrete with different strength and weight. Concrete is very versatile; it can be poured, pumped, or even sprayed into all kinds of shapes. And whereas steel has great tensile strength, concrete has great strength under compression. Thus, the two substances complement each other.They also complement each other in another way: they have almost the same rate ofcontraction and expansion. They therefore can work together in situations where both compression and tension are factors. Steel rods are embedded in concrete to make reinforced concrete in concrete beams or structures where tensions will develop. Concrete and steel also form such a strong bond─ the force that unites them─ that the steel cannot slip within the concrete. Still another advantage is that steel does not rust in concrete. Acid corrodes steel, whereas concrete has an alkaline chemical reaction, the opposite of acid.The adoption of structural steel and reinforced concrete caused major changes in traditional construction practices. It was no longer necessary to use thick walls of stone or brick for multistory buildings, and it became much simpler to build fire-resistant floors. Both these changes served to reduce the cost of construction. It also became possible to erect buildings with greater heights and longer spans.Since the weight of modern structures is carried by the steel or concrete frame, the walls do not support the building. They have become curtain walls, which keep out the weather and let in light. In the earlier steel or concrete frame building, the curtain walls were generally made of masonry; they had the solid look of bearing walls. Today, however, curtain walls are often made of lightweight materials such as glass, aluminum, or plastic, in various combinations.Another advance in steel construction is the method of fastening together the beams. For many years the standard method was riveting. A rivet is a bolt with a head that looks like a blunt screw without threads. It is heated, placed in holes through the pieces of steel, and a second head is formed at the other end by hammering it to hold it in place. Riveting has now largely been replaced by welding, the joining together of pieces of steel by melting a steel material between them under high heat.Priestess’s concrete is an improved form of reinforcement. Steel r ods are bent into the shapes to give them the necessary degree of tensile strengths. They are then used to priestess concrete, usually by one of two different methods. The first is to leave channels in a concrete beam that correspond to the shapes of the steel rods. When the rods are run through the channels, they are then bonded to the concrete by filling the channels with grout, a thin mortar or binding agent. In the other (and more common) method, the priestesses steel rods are placed in the lower part of a form that corresponds to the shape of the finished structure, and the concrete is poured around them. Priestess’s concrete uses less steel and less concrete. Because it is a highly desirable material.Progressed concrete has made it possible to develop buildings with unusual shapes, like some of the modern, sports arenas, with large spaces unbroken by any obstructing supports. The uses for this relatively new structural method are constantly being developed.建筑中的结构设计及建筑材料专业:土木工程学生:指导老师:建筑师必须从一种全局的角度出发去处理建筑设计中应该考虑到的实用活动,物质及象征性的需求。

毕业设计外文翻译英文加中文

毕业设计外文翻译英文加中文

A Comparison of Soft Start Mechanisms for Mining BeltConveyors1800 Washington Road Pittsburgh, PA 15241 Belt Conveyors are an important method for transportation of bulk materials in the mining industry. The control of the application of the starting torque from the belt drive system to the belt fabric affects the performance, life cost, and reliability of the conveyor. This paper examines applications of each starting method within the coal mining industry.INTRODUCTIONThe force required to move a belt conveyor must be transmitted by the drive pulley via friction between the drive pulley and the belt fabric. In order to transmit power there must be a difference in the belt tension as it approaches and leaves the drive pulley. These conditions are true for steady state running, starting, and stopping. Traditionally, belt designs are based on static calculations of running forces. Since starting and stopping are not examined in detail, safety factors are applied to static loadings (Harrison, 1987). This paper will primarily address the starting or acceleration duty of the conveyor. The belt designer must control starting acceleration to prevent excessive tension in the belt fabric and forces in the belt drive system (Suttees, 1986). High acceleration forces can adversely affect the belt fabric, belt splices, drive pulleys, idler pulleys, shafts, bearings, speed reducers, and couplings. Uncontrolled acceleration forces can cause belt conveyor system performance problems with vertical curves, excessive belt take-up movement, loss of drive pulley friction, spillage of materials, and festooning of the belt fabric. The belt designer is confronted with two problems, The belt drive system must produce a minimum torque powerful enough to start the conveyor, and controlled such that the acceleration forces are within safe limits. Smooth starting of the conveyor can be accomplished by the use of drive torque control equipment, either mechanical or electrical, or a combination of the two (CEM, 1979).SOFT START MECHANISM EVALUATION CRITERIONWhat is the best belt conveyor drive system? The answer depends on many variables. The best system is one that provides acceptable control for starting, running, and stopping at a reasonable cost and with high reliability (Lewdly and Sugarcane, 1978). Belt Drive System For the purposes of this paper we will assume that belt conveyors are almost always driven byelectrical prime movers (Goodyear Tire and Rubber, 1982). The belt "drive system" shall consist of multiple components including the electrical prime mover, the electrical motor starter with control system, the motor coupling, the speed reducer, the low speed coupling, the belt drive pulley, and the pulley brake or hold back (Cur, 1986). It is important that the belt designer examine the applicability of each system component to the particular application. For the purpose of this paper, we will assume that all drive system components are located in the fresh air, non-permissible, areas of the mine, or in non-hazardous, National Electrical Code, Article 500 explosion-proof, areas of the surface of the mine.Belt Drive Component Attributes SizeCertain drive components are available and practical in different size ranges. For this discussion, we will assume that belt drive systems range from fractional horsepower to multiples of thousands of horsepower. Small drive systems are often below 50 horsepower. Medium systems range from 50 to 1000 horsepower. Large systems can be considered above 1000 horsepower. Division of sizes into these groups is entirely arbitrary. Care must be taken to resist the temptation to over motor or under motor a belt flight to enhance standardization. An over motored drive results in poor efficiency and the potential for high torques, while an under motored drive could result in destructive overspending on regeneration, or overheating with shortened motor life (Lords, et al., 1978).Torque ControlBelt designers try to limit the starting torque to no more than 150% of the running torque (CEMA, 1979; Goodyear, 1982). The limit on the applied starting torque is often the limit of rating of the belt carcass, belt splice, pulley lagging, or shaft deflections. On larger belts and belts with optimized sized components, torque limits of 110% through 125% are common (Elberton, 1986). In addition to a torque limit, the belt starter may be required to limit torque increments that would stretch belting and cause traveling waves. An ideal starting control system would apply a pretension torque to the belt at rest up to the point of breakaway, or movement of the entire belt, then a torque equal to the movement requirements of the belt with load plus a constant torque to accelerate the inertia of the system components from rest to final running speed. This would minimize system transient forces and belt stretch (Shultz, 1992). Different drive systems exhibit varying ability to control the application of torques to the belt at rest and at different speeds. Also, the conveyor itself exhibits two extremes of loading. An empty belt normally presents the smallest required torque for breakaway and acceleration, while a fully loaded belt presents the highest required torque. A mining drive system must be capable of scaling the applied torque from a 2/1 ratio for a horizontal simple belt arrangement, to a 10/1 ranges for an inclined or complex belt profile.Thermal RatingDuring starting and running, each drive system may dissipate waste heat. The waste heat may be liberated in the electrical motor, the electrical controls,, the couplings, the speed reducer, or the belt braking system. The thermal load of each start Is dependent on the amount of belt load and the duration of the start. The designer must fulfill the application requirements for repeated starts after running the conveyor at full load. Typical mining belt starting duties vary from 3 to 10 starts per hour equally spaced, or 2 to 4 starts in succession. Repeated starting may require the dreading or over sizing of system components. There is a direct relationship between thermal rating for repeated starts and costs. Variable Speed. Some belt drive systems are suitable for controlling the starting torque and speed, but only run at constant speed. Some belt applications would require a drive system capable of running for extended periods at less than full speed. This is useful when the drive load must be shared with other drives, the belt is used as a process feeder for rate control of the conveyed material, the belt speed is optimized for the haulage rate, the belt is used at slower speeds to transport men or materials, or the belt is run a slow inspection or inching speed for maintenance purposes (Hager, 1991). The variable speed belt drive will require a control system based on some algorithm to regulate operating speed. Regeneration or Overhauling Load. Some belt profiles present the potential for overhauling loads where the belt system supplies energy to the drive system. Not all drive systems have the ability to accept regenerated energy from the load. Some drives can accept energy from the load and return it to the power line for use by other loads. Other drives accept energy from the load and dissipate it into designated dynamic or mechanical braking elements. Some belt profiles switch from motoring to regeneration during operation. Can the drive system accept regenerated energy of a certain magnitude for the application? Does the drive system have to control or modulate the amount of retarding force during overhauling? Does the overhauling occur when running and starting? Maintenance and Supporting Systems. Each drive system will require periodic preventative maintenance. Replaceable items would include motor brushes, bearings, brake pads, dissipation resistors, oils, and cooling water. If the drive system is conservatively engineered and operated, the lower stress on consumables will result in lower maintenance costs. Some drives require supporting systems such as circulating oil for lubrication, cooling air or water, environmental dust filtering, or computer instrumentation. The maintenance of the supporting systems can affect the reliability of the drive system.CostThe drive designer will examine the cost of each drive system. The total cost is the sum of the first capital cost to acquire the drive, the cost to install and commission the drive, thecost to operate the drive, and the cost to maintain the drive. The cost for power to operate the drive may vary widely with different locations. The designer strives to meet all system performance requirements at lowest total cost. Often more than one drive system may satisfy all system performance criterions at competitive costs.ComplexityThe preferred drive arrangement is the simplest, such as a single motor driving through a single head pulley.However,mechanical, economic,and functional requirements often necessitate the use of complex drives.The belt designer must balance the need for sophistication against the problems that accompany complex systems. Complex systems require additional design engineering for successful deployment. An often-overlooked cost in a complex system is the cost of training onsite personnel, or the cost of downtime as a result of insufficient training.SOFT START DRIVE CONTROL LOGICEach drive system will require a control system to regulate the starting mechanism. The most common type of control used on smaller to medium sized drives with simple profiles is termed "Open Loop Acceleration Control". In open loop, the control system is previously configured to sequence the starting mechanism in a prescribed manner, usually based on time. In open loop control, drive-operating parameters such as current, torque, or speed do not influence sequence operation. This method presumes that the control designer has adequately modeled drive system performance on the conveyor. For larger or more complex belts, "Closed Loop" or "Feedback" control may he utilized. In closed loop control, during starting, the control system monitors via sensors drive operating parameters such as current level of the motor, speed of the belt, or force on the belt, and modifies the starting sequence to control, limit, or optimize one or wore parameters. Closed loop control systems modify the starting applied force between an empty and fully loaded conveyor. The constants in the mathematical model related to the measured variable versus the system drive response are termed the tuning constants. These constants must be properly adjusted for successful application to each conveyor. The most common schemes for closed loop control of conveyor starts are tachometer feedback for speed control and load cell force or drive force feedback for torque control. On some complex systems, It is desirable to have the closed loop control system adjust itself for various encountered conveyor conditions. This is termed "Adaptive Control". These extremes can involve vast variations in loadings, temperature of the belting, location of the loading on the profile, or multiple drive options on the conveyor. There are three commonadaptive methods. The first involves decisions made before the start, or 'Restart Conditioning'. If the control system could know that the belt is empty, it would reduce initial force and lengthen the application of acceleration force to full speed. If the belt is loaded, the control system would apply pretension forces under stall for less time and supply sufficient torque to adequately accelerate the belt in a timely manner. Since the belt only became loaded during previous running by loading the drive, the average drive current can be sampled when running and retained in a first-in-first-out buffer memory that reflects the belt conveyance time. Then at shutdown the FIFO average may be use4 to precondition some open loop and closed loop set points for the next start. The second method involves decisions that are based on drive observations that occur during initial starting or "Motion Proving'. This usually involves a comparison In time of the drive current or force versus the belt speed. if the drive current or force required early in the sequence is low and motion is initiated, the belt must be unloaded. If the drive current or force required is high and motion is slow in starting, the conveyor must be loaded. This decision can be divided in zones and used to modify the middle and finish of the start sequence control. The third method involves a comparison of the belt speed versus time for this start against historical limits of belt acceleration, or 'Acceleration Envelope Monitoring'. At start, the belt speed is measured versus time. This is compared with two limiting belt speed curves that are retained in control system memory. The first curve profiles the empty belt when accelerated, and the second one the fully loaded belt. Thus, if the current speed versus time is lower than the loaded profile, it may indicate that the belt is overloaded, impeded, or drive malfunction. If the current speed versus time is higher than the empty profile, it may indicate a broken belt, coupling, or drive malfunction. In either case, the current start is aborted and an alarm issued.CONCLUSIONThe best belt starting system is one that provides acceptable performance under all belt load Conditions at a reasonable cost with high reliability. No one starting system meets all needs. The belt designer must define the starting system attributes that are required for each belt. In general, the AC induction motor with full voltage starting is confined to small belts with simple profiles. The AC induction motor with reduced voltage SCR starting is the base case mining starter for underground belts from small to medium sizes. With recent improvements, the AC motor with fixed fill fluid couplings is the base case for medium to large conveyors with simple profiles. The Wound Rotor Induction Motor drive is the traditional choice for medium to large belts with repeated starting duty or complex profilesthat require precise torque control. The DC motor drive, Variable Fill Hydrokinetic drive, and the Variable Mechanical Transmission drive compete for application on belts with extreme profiles or variable speed at running requirements. The choice is dependent on location environment, competitive price, operating energy losses, speed response, and user familiarity. AC Variable Frequency drive and Brush less DC applications are limited to small to medium sized belts that require precise speed control due to higher present costs and complexity. However, with continuing competitive and technical improvements, the use of synthesized waveform electronic drives will expand.REFERENCES[1]Michael L. Nave, P.E.1989.CONSOL Inc.煤矿业带式输送机几种软起动方式的比较1800 年华盛顿路匹兹堡, PA 15241带式运送机是采矿工业运输大批原料的重要方法。

预应力混凝土Prestressed-Concrete大学毕业论文外文文献翻译及原文

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%。

桥梁毕业设计外文翻译5

桥梁毕业设计外文翻译5

附录附录A 外文翻译第一部分英文原文4.2.2 Model that Failed in Punching ShearIt was realized that complete restraint in both the longitudinal and transversedirections is necessary for the development of the internal arching system in the deck slab. With this realization,another half-scale model of a two-girder bridge was built. This model also had a deck slab reinforced only by polypropylene fibres, and was very similar to the previous one, the main difference being that the top flangesof the girders were now interconnected by transverse steel straps lying outside the deck slab. A view of the steel work of this model can be seen in Fig. 4.7.These straps were provided so as to serve as transverse ties to the internal arch in the slab.The 100 mm thick slab of the model with transverse straps failed under a central load of 418 kN in a punching-shear failure mode. As can be seen in Fig. 4.8, the damaged area of the slab was highly localized. It can be appreciated that with such a high failure load, the thin deck slab of the half-scale model could have easily withstood the weights of even the heaviest wheel load of commercial vehicles.The model tests described above and in sub-section 4.2.1 clearly demonstrate that an internal arching action will indeed develop in a deck slab, but only if it is suitably restrained.4.2.3 Edge StiffeningA further appreciation of the deck slab arching action is provided by tests on a scale model of a skew slab-on-girder bridge. As will be discussed in sub-section 4.4.2, one transverse free edge of the deck slab of this model was stiffened by a composite steel channel with its web in the vertical plane. The other free edge was stiffened by a steel channel diaphragm with its web horizontal and connected to the deck slab through shear connectors. The deck slab near the former transverse edge failed in a mode that was a hybrid between punching shear and flexure. Tests near the composite diaphragm led to failure at a much higher load in punching shear (Bakht and Agarwal, 1993).The above tests confirmed yet again that the presence of the internal arching action in deck slabs induces high in-plane force effects which in turn demand stiffer restraint in the plane of the deck than in the out-of-plane direction.4.3 INTERNALLY RESTRAINED DECK SLABSDeck slabs which require embedded reinforcement for strength will now be referred to as internally restrained deck slabs. The state-of-art up to 1986 relating to the quantification and utilization of the beneficial internal arching action in deck slabs with steel reinforcement has been provided by Bakht and Markovic (1986). Their conclusions complemented with up-to-date information are presented in this chapter in a generally chronological order which, however, cannot be adhered to rigidlybecause of the simultaneous occurrence of some developments.4.3.1 Static Tests on Scale ModelsAbout three decades ago, the Structures Research Office of the Ministry of Transportation of Ontario (MTO), Canada, sponsored an extensive laboratory-based research program into the load carrying capacity of deck slabs; this research program was carried out at Queen's University, Kingston, Ontario. Most of this research was conducted through static tests on scale models of slab-on-girder bridges. This pioneering work is reported by Hewitt and Batchelor (1975) and later by Batchelor et al. (1985), and is summarized in the following.The inability of the concrete to sustain tensile strains, which leads to cracking, has been shown to be the main attribute which causes the compressive membrane forces to develop. This phenomenon is illustrated in Fig. 4.9 (a) which shows the part cross-section of slab-on-girder bridge under the action of a concentrated load.The cracking of the concrete, as shown in the figure, results in a net compressive force near the bottom face of the slab at each of the two girder locations. Midway between the girders, the net compressive force moves towards the top of the slab. It can be readily visualized that the transition of the net compressive force from near the top in the middle region, to near the bottom at the supports corresponds to the familiar arching action. Because of this internal arching action, the failure mode of a deck slab under a concentrated load becomes that of punching shear.If the material of the deck slab has the same stress-strain characteristics in both tension and compression, the slab will not crack and, as shown in Fig. 4.9 (b), will not develop the net compressive force and hence the arching action.In the punching shear type of failure, a frustum separates from the rest of the slab, as shown in schematically in Fig. 4.10. It is noted that in most failure tests, the diameter of the lower end of the frustrum extends to the vicinity of the girders.From analytical and confirmatory laboratory studies, it was established that the most significant factor influencing the failure load of a concrete deck slab is the confinement of the panel under consideration. It was concluded that this confinement is provided by the expanse of the slab beyond the loaded area; its degree was founddifficult to assess analytically. A restraint factor, η, was used as an empirical measure of the confinement; its value is equal to zero for the case of no confinement and 1.0 for full confinement.The effect of various parameters on the failure load can be seen in Table 4.1, which lists the theoretical failure loads for various cases. It can be seen that an increase of the restraint factor from 0.0 to 0.5 results in a very large increase in the failure load. The table also emphasizes the fact that neglect of the restraint factor causes a gross underestimation of the failure load.It was concluded that design for flexure leads to the inclusion of large amounts of unnecessary steel reinforcement in the deck slabs, and that even the minimum amount of steel required for crack control against volumetric changes in concrete is adequate to sustain modern-day, and even future, highway vehicles of North America.It was recommended that for new construction, the reinforcement in a deck slab should be in two layers, with each layer consisting of an orthogonal mesh having the same area of reinforcement in each direction. The area of steel reinforcement in each direction of a mesh was suggested to be 0.2% of the effective area of cross-section of the slab. This empirical method of design was recommended for deck slabs with certain constraints.4.3.2 Pulsating Load Tests on Scale ModelsTo study the fatigue strength of deck slabs with reduced reinforcement, five small scale models with different reinforcement ratios in different panels were tested at the Queen's University at Kingston. Details of this study are reported by Batchelor et al. (1978).Experimental investigation confirmed that for loads normally encountered in North America deck slabs with both conventional and recommended reducedreinforcement have large reserve strengths against failure by fatigue. It was confirmed that the reinforcement in the deck slab should be as noted in sub-section 4.3.1. It is recalled that the 0.2% reinforcement requires that the deck slab must have a minimum restraint factor of 0.5.The work of Okada, et al. (1978) also deals with fatigue tests on full scale models of deck slabs and segments of severely cracked slab removed from eight to ten year old bridges. The application of these test results to deck slabs of actual bridges is open to question because test specimens were removed from the original structures in such a way that they did not retain the confinement necessary for the development of the arching action.4.3.3 Field TestingAlong with the studies described in the preceding sub-section, a program of field testing of the deck slabs of in-service bridges was undertaken by the Structures Research Office of the MTO. The testing consisted of subjecting deck slabs to single concentrated loads, simulating wheel loads, and monitoring the load-deflection characteristics of the slab. The testing is reported by Csagoly et al. (1978) and details of the testing equipment are given by Bakht and Csagoly (1979).Values of the restraint factor, η, were back-calculated from measured deflections.A summary of test results, given in Table 4.2, shows that the average value of η in composite bridges is greater than 0.75, while that for non-composite bridges is 0.42. It was concluded that for new construction, the restraint factor, η, can be assumed to have a minimum value of 0.5.Bakht (1981) reports that after the first application of a test load of high magnitude on deck slabs of existing bridges, a small residual deflection was observed in most cases. Subsequent applications of the same load did not result in further residual deflections. It is postulated that the residual deflections are caused by cracking of the concrete which, as discussed earlier, accompanies the development of the internal arching action. The residual deflections after the first cycle of loading suggest that either the slab was never subjected to loads high enough to cause cracking, or the cracks have 'healed' with time.第二部分汉语翻译4.2.2 在冲切剪应力下的实效模型我们已经知道在桥面板内部拱形系统的形成中,不仅纵向而且横向也被完全约束限制是完全必要的。

驱动桥毕业设计外文翻译

驱动桥毕业设计外文翻译

毕业设计/论文外文文献翻译系别自动化系专业班级机械电子工程0603班姓名评分指导教师2010 年4月29日毕业设计/论文外文文献翻译要求:1.外文文献翻译的内容应与毕业设计/论文课题相关。

2.外文文献翻译的字数:非英语专业学生应完成与毕业设计/论文课题内容相关的不少于2000汉字的外文文献翻译任务(其中,汉语言文学专业、艺术类专业不作要求),英语专业学生应完成不少于2000汉字的二外文献翻译任务。

格式按《华中科技大学武昌分校本科毕业设计/论文撰写规范》的要求撰写。

3.外文文献翻译附于开题报告之后:第一部分为译文,第二部分为外文文献原文,译文与原文均需单独编制页码(底端居中)并注明出处。

本附件为封面,封面上不得出现页码。

4.外文文献翻译原文由指导教师指定,同一指导教师指导的学生不得选用相同的外文原文。

驱动桥设计随着汽车对安全、节能、环保的不断重视,汽车后桥作为整车的一个关键部件,其产品的质量对整车的安全使用及整车性能的影响是非常大的,因而对汽车后桥进行有效的优化设计计算是非常必要的。

驱动桥处于动力传动系的末端,其基本功能是增大由传动轴或变速器传来的转矩,并将动力合理地分配给左、右驱动轮,另外还承受作用于路面和车架或车身之间的垂直力力和横向力。

驱动桥一般由主减速器、差速器、车轮传动装置和驱动桥壳等组成。

驱动桥作为汽车四大总成之一,它的性能的好坏直接影响整车性能,而对于载重汽车显得尤为重要。

驱动桥设计应当满足如下基本要求:1、符合现代汽车设计的一般理论。

2、外形尺寸要小,保证有必要的离地间隙。

3、合适的主减速比,以保证汽车的动力性和燃料经济性。

4、在各种转速和载荷下具有高的传动效率。

5、在保证足够的强度、刚度条件下,力求质量小,结构简单,加工工艺性好,制造容易,拆装,调整方便。

6、与悬架导向机构运动协调,对于转向驱动桥,还应与转向机构运动协调。

智能电子技术在汽车上得以推广使得汽车在安全行驶和其它功能更上一层楼。

桥梁工程本科毕业设计外文翻译---混凝土桥梁的结构形式

桥梁工程本科毕业设计外文翻译---混凝土桥梁的结构形式

本科毕业设计外文翻译混凝土桥梁的结构形式院(系、部)名称:专业名称:学生姓名:学生学号:指导教师:The Structure of Concrete BridgePre-stressed concrete has proved to be technically advantageous, economically competitive, and esthetically superior bridges, from very short span structures using standard components to cable-stayed girders and continuous box girders with clear spans of nearly 100aft .Nearly all concrete bridges, even those of relatively short span, are now pre-stressed. Pre-casting, cast-in-place construction, or a combination of the two methods may be used .Both pre-tensioning and post tensioning are employed, often on the same project.In the United States, highway bridges generally must-meet loading ,design ,and construction requirements of the AASHTO Specification .Design requirements for pedestrian crossings and bridges serving other purposes may be established by local or regional codes and specifications .ACI Code provisions are often incorporated by reference .Bridges spans to about 100ft often consist of pre-cast integral-deck units ,which offer low initial cost ,minimum ,maintenance ,and fast easy construction ,with minimum traffic interruption .Such girders are generally pre-tensioned .The units are placed side by side ,and are often post-tensioned laterally at intermediate diaphragm locations ,after which shear keys between adjacent units are filled with non-shrinking mortar .For highway spans ,an asphalt wearing surface may be applied directly to the top of the pre-cast concrete .In some cases ,a cast-in-place slab is placed to provide composite action .The voided slabs are commonly available in depths from 15 to 21 in .and widths of 3 to 4 ft .For a standard highway HS20 loading, they are suitable for spans to about 50 ft, Standard channel sections are available in depths from 21 to 35 in a variety of widths, and are used for spans between about 20 and 60 ft .The hollow box beams-and single-tee girders are intended for longer spans up to about 100 ft.For medium-span highway bridges ,to about 120 ft ,AASHTO standard I beams are generally used .They are intended for use with a composite cast-in-place roadway slab .Such girders often combine pre-tensioning of the pre-cast member with post-tensioning of the composite beam after the deck is placed .In an effort to obtain improved economy ,some states have adopted more refined designs ,such as the State of Washington standard girders.The specially designed pre-cast girders may be used to carry a monorail transit system .The finished guide way of Walt Disney World Monorail features a series of segments, each consisting of six simply supported pre-tensioned beams ,together to from a continuous structure .Typical spans are 100 to 110 ft . Approximately half of the 337 beams used have some combination of vertical and horizontal curvatures and variable super elevation .Allbeams are hollow, a feature achieved by inserting a styro-foam void in the curved beams and by a moving mandrel in straight beam production.Pre-cast girders may not be used for spans much in excess of 120 ft because of the problems of transporting and erecting large, heavy units.On the other hand ,there is a clear trend toward the use of longer spans for bridges .For elevated urban expressways ,long spans facilitate access and minimize obstruction to activities below .Concern for environmental damage has led to the choice of long spans for continuous viaducts . For river crossings, intermediate piers may be impossible because of requirements of navigational clearance.In typical construction of this type, piers are cast-in-place, often using the slip-forming technique .A “hammerhead” section of box girder is often cast at the top of the pier, and construction proceeds in each direction by the balanced cantilever method. Finally, after the closing cast-in-place joint is made at mid-span, the structure is further post-tensioned for full continuity .Shear keys may be used on the vertical faces between segments, and pre-cast are glued with epoxy resin.The imaginative engineering demonstrated by many special techniques has extended the range of concrete construction for bridges far beyond anything that could be conceived just a few years ago .In the United States, twin curved cast-in –place segmental box girders have recently been completed for of span of 310 ft over the Eel River in northern California .Preliminary design has been completed for twin continuous box girders consisting of central 550 ft spans flanked by 390 ft side spans.Another form of pre-stressed concrete bridge well suited to long spans is the cable-stayed box girder .A notable example is the Chaco-Corrientes Bridge in Argentina .The bridges main span of 804 ft is supported by two A-frame towers, with cable stays stretching from tower tops to points along the deck .The deck itself consists of two parallel box girders made of pre-cast sections erected using the cantilever method .The tensioned cables not only provide a vertical reaction component to support the deck ,but also introduce horizontal compression to the box girders ,adding to the post-tensioning force in those members .Stress-ribbon Bridge pioneered many years ago by the German engineer Ulrich Finsterwalder. The stress-ribbon bridge carries a pipeline and pedestrians over the Rhine River with a span of 446 ft .The superstructure erection sequence was to (a) erect two pairs of cables, (b) place pre-cast slabs forming a sidewalk deck and a U under each of the sets of cables, and (c) cast-in-place concrete within the two Us. The pipeline is placed atop supports at railing height, off to one side, which greatly increases the wind speed of the structure.It is appropriate in discussing bridge forms to mention structural esthetics .The time ispast when structures could be designed on the basis of minimum cost and technical advantages alone .Bridge structures in particular are exposed for all to see .To produce a structure that is visually offensive ,as has occurred all too often in the past, is an act professional irresponsibility .Particularly for major spans ,but also for more ordinary structures ,architectural advice should be sought early in conceptual stage of the design process.混凝土梁桥的结构形式事实证明,预应力混凝土结构是在技术上先进、经济上有竞争力、符合审美学的一种先进技术。

毕业设计(论文)外文翻译【范本模板】

毕业设计(论文)外文翻译【范本模板】

华南理工大学广州学院本科生毕业设计(论文)翻译英文原文名Review of Vibration Analysis Methods for Gearbox Diagnostics and Prognostics中文译名对变速箱振动分析的诊断和预测方法综述学院汽车工程学院专业班级车辆工程七班学生姓名刘嘉先学生学号201130085184指导教师李利平填写日期2015年3月15日英文原文版出处:Proceedings of the 54th Meeting of the Society for Machinery Failure Prevention Technology, Virginia Beach,V A, May 1-4,2000,p. 623-634译文成绩:指导教师(导师组长)签名:译文:简介特征提取技术在文献中有描述;然而,大多数人似乎掩盖所需的特定的预处理功能。

一些文件没有提供足够的细节重现他们的结果,并没有一个全面的比较传统的功能过渡齿轮箱数据。

常用术语,如“残差信号”,是指在不同的文件不同的技术.试图定义了状态维修社区中的常用术语和建立所需的特定的预处理加工特性。

本文的重点是对所使用的齿轮故障检测功能。

功能分为五个不同的组基于预处理的需要。

论文的第一部分将提供预处理流程的概述和其中每个特性计算的处理方案。

在下一节中,为特征提取技术描述,将更详细地讨论每一个功能。

最后一节将简要概述的宾夕法尼亚州立大学陆军研究实验室的CBM工具箱用于齿轮故障诊断。

特征提取概述许多类型的缺陷或损伤会增加机械振动水平。

这些振动水平,然后由加速度转换为电信号进行数据测量。

原则上,关于受监视的计算机的健康的信息被包含在这个振动签名。

因此,新的或当前振动签名可以与以前的签名进行比较,以确定该元件是否正常行为或显示故障的迹象。

在实践中,这种比较是不能奏效的。

由于大的变型中,签名的直接比较是困难的。

相反,一个涉及从所述振动署名数据特征提取更多有用的技术也可以使用。

毕业设计(论文)外文资料翻译(学生用)

毕业设计(论文)外文资料翻译(学生用)

毕业设计外文资料翻译学院:信息科学与工程学院专业:软件工程姓名: XXXXX学号: XXXXXXXXX外文出处: Think In Java (用外文写)附件: 1.外文资料翻译译文;2.外文原文。

附件1:外文资料翻译译文网络编程历史上的网络编程都倾向于困难、复杂,而且极易出错。

程序员必须掌握与网络有关的大量细节,有时甚至要对硬件有深刻的认识。

一般地,我们需要理解连网协议中不同的“层”(Layer)。

而且对于每个连网库,一般都包含了数量众多的函数,分别涉及信息块的连接、打包和拆包;这些块的来回运输;以及握手等等。

这是一项令人痛苦的工作。

但是,连网本身的概念并不是很难。

我们想获得位于其他地方某台机器上的信息,并把它们移到这儿;或者相反。

这与读写文件非常相似,只是文件存在于远程机器上,而且远程机器有权决定如何处理我们请求或者发送的数据。

Java最出色的一个地方就是它的“无痛苦连网”概念。

有关连网的基层细节已被尽可能地提取出去,并隐藏在JVM以及Java的本机安装系统里进行控制。

我们使用的编程模型是一个文件的模型;事实上,网络连接(一个“套接字”)已被封装到系统对象里,所以可象对其他数据流那样采用同样的方法调用。

除此以外,在我们处理另一个连网问题——同时控制多个网络连接——的时候,Java内建的多线程机制也是十分方便的。

本章将用一系列易懂的例子解释Java的连网支持。

15.1 机器的标识当然,为了分辨来自别处的一台机器,以及为了保证自己连接的是希望的那台机器,必须有一种机制能独一无二地标识出网络内的每台机器。

早期网络只解决了如何在本地网络环境中为机器提供唯一的名字。

但Java面向的是整个因特网,这要求用一种机制对来自世界各地的机器进行标识。

为达到这个目的,我们采用了IP(互联网地址)的概念。

IP以两种形式存在着:(1) 大家最熟悉的DNS(域名服务)形式。

我自己的域名是。

所以假定我在自己的域内有一台名为Opus的计算机,它的域名就可以是。

土木工程毕业设计外文翻译--拱桥的设计和桥梁裂缝产生的原因分析

土木工程毕业设计外文翻译--拱桥的设计和桥梁裂缝产生的原因分析

本科毕业设计中英文翻译专业名称:土木工程年级班级:XXX学生姓名:XXX指导教师:XXX土木工程学院二○一二年六月一日Design of arch bridges and the bridge crackproduced the reason to simply analyseThis chapter considers the full range of arch bridge types and a range of materials presenting several case studies and describing the design decisions that were made. A general treatment of the analysis of arches is presented, including the derivation of the basic equations that can be used to undertake hand calculations which may beused to validate computer analysis output. Detailed arch bridge design is outside thescope of this chapter so only general issues are discussed. Most of the chapter is devoted to masonry arch bridges. Masonry arch bridge construction is discussed in its historical context and the importance for engineers to take a holistic approach to bridge assessment and design is emphasized. There is a significant section on bridge assessment which includes guidance in the application of current and emerging assessment methods. This is underpinned with background information regarding the material properties of masonry. The chapter concludes with a treatment of repair and maintenance strategies including a comprehensive table which considers common remedial and strengthening measures.The origins of the use of arches as a structural form in buildings can be traced back to antiquity (Van Beek, 1987). In trying to arrive at a suitable definition for an arch we may look no further than Hooke‘s anagram of 1675 which stated ‗Ut p endet continuum flexile, sic stabat continuum rigidum inversum‘ –‗as hangs the flexible line, so but inverted will stand the rigid arch‘. This suggests that any given loading to a flexible cable if frozen and inverted will provide a purely compressive structure in equilibrium with the applied load. Clearly, any slight variation in the loading will result in a moment being induced in the arch. It is arriving at appropriate proportions of arch thickness to accommodate the range of eccentricities of the thrust line that is the challenge to the bridge engineer. Even in the Middle Ages it was appreciated that masonry arches behaved essentially as gravity structures, for which geometry and proportion dictated aesthetic appeal and stability. Compressive strength could be relied upon whilst tensile strength could not. Based upon experience, many empirical relationships between the span and arch thickness were developed and applied successfully to produce many elegant structures throughout Europe.The expansion of the railway and canal systems led to an explosion of bridge building. Brickwork arches became increasingly popular. With the construction of the Coalbrookdale Bridge (1780) a new era of arch bridge construction began. By the end of the nineteenth century cast iron, wrought iron and finally steel became increasingly popular; only to be challenged by ferro cement (reinforced concrete) at the turn of the century.During the nineteenth century analytical technique developed apace. In particular, Castigliano (1879) developed strain energy theorems which could be applied to arches provided they remained elastic. This condition could be satisfied provided the line of thrust lay within the middle third, thus ensuring that no tensile stresses were induced. The requirement to avoid tensile stresses only applied to masonry and cast iron; it did not apply to steel or reinforced concrete (or timber for that matter) as these materials were capable of resisting tensile stresses.Twentieth century arch bridges have become increasingly sophisticated structures combining modern materials to create exciting functional urban sculptures.Types of arch bridgeThe relevant terms that are used to describe the various parts of an arch bridge are shown in Figure 1. Arches may be grouped according to the following parameters:1. the materials of construction2. the structural articulation3. the shape of the archHistorically, arch bridges are associated with stone masonry. This gave way to brickwork in the nineteenth century. Because these were proportioned to minimise the possibility oftensile stress, they tend to be fairly massive structures. By comparison the use of reinforced concrete and modern structural steel gives the opportunity for slender, elegant arches.Nowadays, timber is restricted to small bridges occasionally in a truss form but more usually as laminated curved arches. Although timber has a high strength to density ratio parallel to the grain, it is anisotropic and strength properties perpendicular to the grain are relatively weak. This requires careful detailing of connections to ensure economic use of the material.With regard to structural articulation the arch can be fixed or hinged. In the latter case either one, two or three hinges can be incorporated into the arch rib. Whilst the fixed arch has three redundancies, the introduction of each hinge reduced the indeterminacy by one until, with three hinges, the arch is statically determinate and hence, theoretically, free of the problems of secondary stresses. Figure 2 shows a range of possible arrangements. The articulation of the arch is not only dependent upon the number of hinges but is also fund amentally influenced by the position of the deck and the nature of the load transfer from the deck to the arch.The traditional filled spandrel, where the vehicular loading is transferred through the b ackfill material onto the extrados of the arch, represents at first glance the simplest structural condition. As will be seen later this is not the case and has led to much research for the specific case of the masonry arch bridge in an attempt to improve our understanding of such structures.The spandrel may be open with columns and/or hinges used to transfer the deck loads to the arch. In an attempt to minimise the horizontal thrust on the abutments, the deck may be used to ‗tie‘ the arch. Tied arches are particularly appropriate when deck construction depths are limited and large clear spans are needed (particularly if ground conditions are also difficult and would require extensive piling to resist the horizontal thrusts).Returning to Hooke‘s anagram, the perfect shape for an arch would be an inverted catenary – this would only be the case for carrying its own self-weight. Vehicle loading and varying superincumbent dead load both induce bending moments. Consequently the arch has to have sufficient thickness to accommodate the ‗wandering‘ thrust line.For ease of setting out and construction simpler shapes are adopted nowadays segmental or parabolic shapes are used. Although in situations where maximum widths of headroom have to be provided (say over a railway, road or canal) an elliptical shape may be required or its nearest ‗easy‘ equivalent the three-centred arch.It is worth commenting at this stage regarding the idealization of arch structures.Traditionally arches are perceived as being two-dimensional structures; this, of course is not true – but the extent to which it is not true should be of concern to the designer/assessor. Even in the case of a three-hinged arch whi ch ostensibly is statically determinate the ‗pins‘ are capable of transmitting shear even though they theoretically cannot transmit moments. In the case of non-uniform transverse distribution of loading the hinges will transmit a varying shear which will produce torsion in the arch. Moreover, in the case of skew arches or non-vertical ribs the structure has a much higher redundancy and hence will require greater attention to detail in regard to the releases which are engineered into the structure.From an aesthetic point of view, arches have a universal appeal. In spite of this, care must be taken as the impact of even modest sized bridges is significant. Filled arches are invariably masonry (or widening of masonry) bridges. Cleanness of line, honesty of conception and the attention to detail are vital ingredients to a successful bridge. Certainly, simple stringcourses and copings are preferable to elaborate details which would be expensive and inappropriate for most modern bridges. Where stone is used it is important to be sensitive to the nature of the material. Modern quarrying techniques should be employed (laser cutting, diamond sawing, flame texturing and sandblasting) reserving traditional dressing to conservation schemes. If brickwork is used different textured or coloured bricks and mortar can be specified. Here stringcourses can be particularly useful to mask changes in bedding angle.Historically abutments comprised either rock, or else were massive masonry supports relying on their weight to resist the thrust of the arch. In terms of structural honesty this is necessary as it is instinctive to expect such support.Reinforced concrete and steel arches are altogether much lighter structures. ‗The structure consists basically of the arch, the deck and usually some supports from the arch to the deck – in that order of importance. These elements should be expressed in both form and detail, and with due regard for their hierarchy‘ (Highways Agency, 1996).It is important that the deck, if it rests on the crown of the arch, should not mask it in any way. Any support whether spandrel columns or hinges (in the case of the tied arch) should not be allowed to dominate. Preferably they should be recessed relative to the parapet and stringcourse.Concrete arches can be either a full width curved slab or a series of ribs. Steel is almostalways a series of ribs. Where ribs are used thought should be given (if they are going to be seen from underneath) to the chiaroscuro of the soffit.The ratio of span to rise should generally be in the range 2:1 to 10:1. The flatter the arch the greater the horizontal thrust; this may affect the structural form selected, i. e. whether or not a tie should be introduced, or the stiffness of the deck relative to the arch.In recent years, the traffic capital construction of our country 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 :First, 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 insufficient to design the section; It is simply little andassigning 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 of component form sudden change office, block place to be easy to appear crack strength reinforcing bar of the structure. 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 withmodern 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 appears 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) Central tension. 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 the structure. (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 degreesdirection 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 degrees direction parallel oblique crack each other to appear along roof beam end. (7) Sprained. Component one side belly appear many direction oblique crack, 45 degrees of treaty, first, and to launch with spiral direction being adjoint. (8) Washed and cut. 4 side is it invite 45 degrees 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.Second, crack caused in temperature change.The 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 the range 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 thetemperature 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.Third , shrink the crack caused.In 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 mainreason 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 layer moisture 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 themajority 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 in addition, 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。

毕业设计(论文)外文资料翻译【范本模板】

毕业设计(论文)外文资料翻译【范本模板】

南京理工大学紫金学院毕业设计(论文)外文资料翻译系:机械系专业:车辆工程专业姓名:宋磊春学号:070102234外文出处:EDU_E_CAT_VBA_FF_V5R9(用外文写)附件:1。

外文资料翻译译文;2.外文原文.附件1:外文资料翻译译文CATIA V5 的自动化CATIA V5的自动化和脚本:在NT 和Unix上:脚本允许你用宏指令以非常简单的方式计划CATIA。

CATIA 使用在MS –VBScript中(V5.x中在NT和UNIX3。

0 )的共用部分来使得在两个平台上运行相同的宏。

在NT 平台上:自动化允许CATIA像Word/Excel或者Visual Basic程序那样与其他外用分享目标。

ATIA 能使用Word/Excel对象就像Word/Excel能使用CATIA 对象。

在Unix 平台上:CATIA将来的版本将允许从Java分享它的对象。

这将提供在Unix 和NT 之间的一个完美兼容。

CATIA V5 自动化:介绍(仅限NT)自动化允许在几个进程之间的联系:CATIA V5 在NT 上:接口COM:Visual Basic 脚本(对宏来说),Visual Basic 为应用(适合前:Word/Excel ),Visual Basic。

COM(零部件目标模型)是“微软“标准于几个应用程序之间的共享对象。

Automation 是一种“微软“技术,它使用一种解释环境中的COM对象。

ActiveX 组成部分是“微软“标准于几个应用程序之间的共享对象,即使在解释环境里。

OLE(对象的链接与嵌入)意思是资料可以在一个其他应用OLE的资料里连结并且可以被编辑的方法(在适当的位置编辑).在VBScript,VBA和Visual Basic之间的差别:Visual Basic(VB)是全部的版本。

它能产生独立的计划,它也能建立ActiveX 和服务器。

它可以被编辑。

VB中提供了一个补充文件名为“在线丛书“(VB的5。

桥梁毕业设计外文翻译--对木桥的负载和阻力系数的校准

桥梁毕业设计外文翻译--对木桥的负载和阻力系数的校准

对木桥的负载和阻力系数的校准内容摘要:这篇论文为木桥设计规范的确定发展提供了校准方法和基本数据。

结构类型被认为包括锯成的木梁、胶合梁及各种类型的木梁板。

负载和阻力参数被视为随机变量,因而,结构特性是根据可靠性指标来测定的。

桥的恒载和交通活载,都是基于先前的研究结果。

材料的阻值是取自可用的测试得来的数据,这些数据中包含了考虑有弹性反应作用的数据。

阻力的组成和结构系统是基于可利用的实验数据和有限元分析的结果。

阻力的统计参数是由梁板、梁体及个别的组件计算而得。

对木桥进行可靠性分析设计应依照AASHTO标准设计规范并且要注意到可靠性指标中的一个重要变化,负载限度和阻力系数应该和可靠性程度及目标水准相一致。

DOL:10.1061/(ASCE)1084-0702(2005)10:6(636)土木工程师数据库的关键词:桥梁、木制的、校准、负载和阻力系数、设计、桥板。

考虑结构类型这类校准工作是为了选定一些典型的木桥类型而做的。

尤其,那些单跨、双车道、直线型的由木制部件组成的桥梁,比中跨度桥梁要短,其长度从4米到25米(13英尺到80英尺)不等。

一般而言,有两种类型的木桥:梁体结构(纵梁或主梁)或者板体结构。

由加工过的木材制造而成的纵桁梁桥是适用于短跨桥中,其最大可跨越大概8米(25英尺)。

现成的已锯成木梁通常为100 - 150毫米宽(4到6英寸),300至400毫米(12到16英寸)长,这些尺寸大小限制着中心间距使其通常不超过400-600毫米(16到24英寸)。

然而,使用更大的宽度,如20毫米(8英寸)和更大的长度,这些可能使梁间距增大,直到最后受限于面板的承载能力为止。

胶合梁可采用更大的长度和宽度,从而可以跨越更大的距离,是梁间距更宽。

比较常见的跨度是6米到24米(20到80英尺)。

这类梁支持各种不同类型的木材板,它可以是胶合薄板(多层胶合木)、钉制成薄板(多层钉合板)、组合板(用长钉钉合的多层板)、厚木板(4英寸×6英寸,4英寸×8英寸,4英寸×10英寸及4英寸×12英寸)、应力板(多层应力作用板)和钢筋混凝土板(非混合型的)。

道路与桥梁专业外文翻译中英对照

道路与桥梁专业外文翻译中英对照

本科毕业设计论文专业外文翻译专业名称:土木工程专业道路与桥梁年级班级:道桥08-5班学生姓名:指导教师:二○一二年五月十八日Geometric Design of HighwaysThe road is one kind of linear construction used for travel. It is made of the roadbed, the road surface, the bridge, the culvert and the tunnel. In addition, it also has the crossing of lines, the protective project and the traffic engineering and the route facility.The roadbed is the base of road surface, road shoulder, side slope, side ditch foundations. It is stone material structure, which is designed according to route's plane position .The roadbed, as the base of travel, must guarantee that it has the enough intensity and the stability that can prevent the water and other natural disaster from corroding.The road surface is the surface of road. It is single or complex structure built with mixture. The road surface require being smooth, having enough intensity, good stability and anti-slippery function. The quality of road surface directly affects the safe, comfort and the traffic.Highway geometry designs to consider Highway Horizontal Alignment, Vertical Alignment two kinds of linear and cross-sectional composition of coordination, but also pay attention to the smooth flow of the line of sight, etc. Determine the road geometry, consider the topography, surface features, rational use of land and environmental protection factors, to make full use of the highway geometric components of reasonable size and the linear combination.DesignThe alignment of a road is shown on the plane view and is a series of straight lines called tangents connected by circular. In modern practice it is common to interpose transition or spiral curves between tangents and circular curves.Alignment must be consistent. Sudden changes from flat to sharp curves and long tangents followed by sharp curves must be avoided; otherwise, accident hazards will be created. Likewise, placing circular curves of different radii end to end compound curves or having a short tangent between two curves is poor practice unless suitable transitions between them are provided. Long, flat curves are preferable at all times, as they are pleasing in appearance and decrease possibility of future obsolescence. However, alignment without tangents is undesirable on two-lane roads because some drivers hesitate to pass on curves. Long, flat curves should be used for small changes in direction, as short curves appear as “kink”. Also horizontal and vertical alignment must be considered together, not separately. For example, a sharp horizontal curve beginning near a crest can create a serious accident hazard.A vehicle traveling in a curved path is subject to centrifugal force. This is balanced by an equal and opposite force developed through cannot exceed certain maximums, and these controls place limits on the sharpness of curves that can be used with a design speed. Usually the sharpness of a given circular curve is indicated by its radius. However, for alignment design, sharpness is commonly expressed in terms of degree of curve, which is the central angle subtended by a 100-ft length of curve. Degree of curve is inversely proportional to the radius.Tangent sections of highways carry normal cross slope; curved sections are super elevated. Provision must be made for gradual change from one to the other. This usually involves maintaining the center line of each individual roadway at profile grade while raising the outer edge and lowering the inner edge to produce the desired super elevation is attained some distance beyond the point of curve.If a vehicle travels at high speed on a carefully restricted path made up of tangents connected by sharp circular curve, riding is extremely uncomfortable. As the car approaches a curve, super elevation begins and the vehicle is tilted inward, but the passenger must remain vertical since there is on centrifugal force requiring compensation. When the vehicle reaches the curve, full centrifugal force develops at once, and pulls the rider outward from his vertical position. To achieve a position of equilibrium he must force his body far inward. As the remaining super elevation takes effect, further adjustment in position is required. This process is repeated in reverse order as the vehicle leaves the curve. When easement curves are introduced, the change in radius from infinity on the tangent to that of the circular curve is effected gradually so that centrifugal force also develops gradually. By careful application of super elevation along the spiral, a smooth and gradual application of centrifugal force can be had and the roughness avoided.Easement curves have been used by the railroads for many years, but their adoption by highway agencies has come only recently. This is understandable. Railroad trains must follow the precise alignment of the tracks, and the discomfort described here can be avoided only by adopting easement curves. On the other hand, the motor-vehicle operator is free to alter his lateral position on the road and can provide his own easement curves by steering into circular curves gradually. However, this weaving within a traffic lane but sometimes into other lanes is dangerous. Properly designed easement curves make weaving unnecessary. It is largely for safety reasons, then, that easement curves have been widely adopted by highway agencies.For the same radius circular curve, the addition of easement curves at the ends changes the location of the curve with relationto its tangents; hence the decision regarding their use should be made before the final location survey. They point of beginning of an ordinary circular curve is usually labeled the PC point of curve or BC beginning of curve. Its end is marked the PT point of tangent or EC end of curve. For curves that include easements, the common notation is, as stationing increases: TS tangent to spiral, SC spiral to circular curve, CS circular curve to spiral, and ST spiral go tangent.On two-lane pavements provision of a wilder roadway is advisable on sharp curves. This will allow for such factors as 1 the tendency for drivers to shy away from the pavement edge, 2 increased effective transverse vehicle width because the front and rear wheels do not track, and 3 added width because of the slanted position of the front of the vehicle to the roadway centerline. For 24-ft roadways, the added width is so small that it can be neglected. Only for 30mph design speeds and curves sharper than 22°does the added width reach 2 ft. For narrower pavements, however, widening assumes importance even on fairly flat curves. Recommended amounts of and procedures for curve widening are given in Geometric Design for Highways.2. GradesThe vertical alignment of the roadway and its effect on the safe and economical operation of the motor vehicle constitute one of the most important features of road design. The vertical alignment, which consists of a series of straight lines connected by vertical parabolic or circular curves, is known as the “grade line.” When the grade line is increasing from the horizontal it is known as a “plus grade,” and when it is decreasing from the horizontal it is known as a “minus grade.” In analyzing grade and grade controls, the designer usually studies the effect of change in grade on the centerline profile.In the establishment of a grade, an ideal situation is one inwhich the cut is balanced against the fill without a great deal of borrow or an excess of cut to be wasted. All hauls should be downhill if possible and not too long. The grade should follow the general terrain and rise and fall in the direction of the existing drainage. In mountainous country the grade may be set to balance excavation against embankment as a clue toward least overall cost. In flat or prairie country it will be approximately parallel to the ground surface but sufficiently above it to allow surface drainage and, where necessary, to permit the wind to clear drifting snow. Where the road approaches or follows along streams, the height of the grade line may be dictated by the expected level of flood water. Under all conditions, smooth, flowing grade lines are preferable to choppy ones of many short straight sections connected with short vertical curves.Changes of grade from plus to minus should be placed in cuts, and changes from a minus grade to a plus grade should be placed in fills. This will generally give a good design, and many times it will avoid the appearance of building hills and producing depressions contrary to the general existing contours of the land. Other considerations for determining the grade line may be of more importance than the balancing of cuts and fills.Urban projects usually require a more detailed study of the controls and finer adjustment of elevations than do rural projects. It is often best to adjust the grade to meet existing conditions because of the additional expense of doing otherwise.In the analysis of grade and grade control, one of the most important considerations is the effect of grades on the operating costs of the motor vehicle. An increase in gasoline consumption and a reduction in speed are apparent when grades are increase in gasoline consumption and a reduction in speed is apparent when grades are increased. An economical approach would be to balancethe added annual cost of grade reduction against the added annual cost of vehicle operation without grade reduction. An accurate solution to the problem depends on the knowledge of traffic volume and type, which can be obtained only by means of a traffic survey.While maximum grades vary a great deal in various states, AASHTO recommendations make maximum grades dependent on design speed and topography. Present practice limits grades to 5 percent of a design speed of 70 mph. For a design speed of 30 mph, maximum grades typically range from 7 to 12 percent, depending on topography. Wherever long sustained grades are used, the designer should not substantially exceed the critical length of grade without the provision of climbing lanes for slow-moving vehicles. Critical grade lengths vary from 1700 ft for a 3 percent grade to 500 ft for an 8 percent grade.Long sustained grades should be less than the maximum grade on any particular section of a highway. It is often preferred to break the long sustained uniform grade by placing steeper grades at the bottom and lightening the grade near the top of the ascent. Dips in the profile grade in which vehicles may be hidden from view should also be avoided. Maximum grade for highway is 9 percent. Standards setting minimum grades are of importance only when surface drainage is a problem as when water must be carried away in a gutter or roadside ditch. In such instances the AASHTO suggests a minimum of %.3. Sight DistanceFor safe vehicle operation, highway must be designed to give drivers a sufficient distance or clear version ahead so that they can avoid unexpected obstacles and can pass slower vehicles without danger. Sight distance is the length of highway visible ahead to the driver of a vehicle. The concept of safe sight distance has two facets: “stopping” or “no passing” and “passing”.At times large objects may drop into a roadway and will do seriousdamage to a motor vehicle that strikes them. Again a car or truck may be forced to stop in the traffic lane in the path of following vehicles. In dither instance, proper design requires that such hazards become visible at distances great enough that drivers can stop before hitting them. Further more, it is unsafe to assume that one oncoming vehicle may avoid trouble by leaving the lane in which it is traveling, for this might result in loss of control or collision with another vehicle.Stopping sight distance is made up of two elements. The first is the distance traveled after the obstruction comes into view but before the driver applies his brakes. During this period of perception and reaction, the vehicle travels at its initial velocity. The second distance is consumed while the driver brakes the vehicle to a stop. The first of these two distances is dependent on the speed of the vehicle and the perception time and brake-reaction time of the operator. The second distance depends on the speed of the vehicle; the condition of brakes, times, and roadway surface; and the alignment and grade of the highway.On two-lane highways, opportunity to pass slow-moving vehicles must be provided at intervals. Otherwise capacity decreases and accidents increase as impatient drivers risk head-on collisions by passing when it is unsafe to do so. The minimum distance ahead that must be clear to permit safe passing is called the passing sight distance. In deciding whether or not to pass another vehicle, the driver must weigh the clear distance available to him against the distance required to carry out the sequence of events that make up the passing maneuver. Among the factors that will influence his decision are the degree of caution that he exercises and the accelerating ability of his vehicle. Because humans differ markedly, passing practices, which depend largely on human judgment and behavior rather than on the laws of mechanics, vary considerablyamong drivers.The geometric design is to ensure highway traffic safety foundation, the highway construction projects around the other highway on geometric design, therefore, in the geometry of the highway design process, if appear any unsafe potential factors, or low levels of combination of design, will affect the whole highway geometric design quality, and the safety of the traffic to bring adverse impact. So, on the geometry of the highway design must be focus on.公路几何设计公路是供汽车或其他车辆行驶的一种线形带状结构体.它是由路基、路面、桥梁、涵洞和隧道组成.此外,它还有路线交叉、工程和交通工程及沿线设施.路基是路面、路肩、边坡、等部分的基础.它是按照路线的平面位置在地面上开挖和成的土物.路基作为行车部分的基础,必须保证它有足够的强度和稳定性,可以防止水及其他自然灾害的侵蚀.路面是公路表面的部分.它是用混合料铺筑的单层或多层结构物.路面要求光滑,具有足够的强度,稳定性好和抗湿滑功能.路面质量的好环,直接影响到行车的安全性、舒适性和通行.公路几何线形设计要考虑公路平面线形、纵断面线形两种线形以及横断面的组成相协调,还要注意视距的畅通等等.确定公路几何线形时,在考虑地形、地物、土地的合理利用及环境保护因素时,要充分利用公路几何组成部分的合理尺寸和线形组合.1、线形设计道路的线形反映在平面图上是由一系列的直线和与直线相连的圆曲线构成的.现代设计时常在直线与圆曲线之间插入缓和曲线.线形应是连续的,应避免平缓线形到小半径曲线的突变或者长直线末端与小半径曲线相连接的突然变化,否则会发生交通事故.同样,不同半径的圆弧首尾相接曲线或在两半径不同的圆弧之间插入短直线都是不良的线形,除非在圆弧之间插入缓和曲线.长而平缓的曲线在任何时候都是可取的,因为这种曲线线形优美,将来也不会废弃.然而,双向道路线形全由曲线构成也是不理想的,因为一些驾驶员通过曲线路段时总是犹豫.长而缓的曲线应用在拐角较小的地方.如果采用短曲线,则会出现“扭结”.另外,线路的平、纵断面设计应综合考虑,而不应只顾其一,不顾其二,例如,当平曲线的起点位于竖曲线的顶点附近时将会产生严重的交通事故.行驶在曲线路段上的车辆受到离心力的作用,就需要一个大小相同方向相反的由超高和侧向磨擦提供的力抵消它,这些控制值对于某一规定设计车速可能采用曲线的曲率作了限制.通常情况下,某一圆曲线的曲率是由其半径来体现的.而对于线形设计而言,曲率常常通过曲线的程度来描述,即100英尺长的曲线所对应的中心角,曲线的程度与曲线的半径成反比.公路的直线地段设置正常的路拱,而曲线地段则设置超高,在正常断面与超高断面之间必须设置过渡渐变路段.通常的做法是维持道路每一条中线设计标高不变,通过抬高外侧边缘,降低内侧边缘以形成所需的超高,对于直线与圆曲线直接相连的线形,超高应从未到达曲线之前的直线上开始,在曲线顶点另一端一定距离以外达到全部超高.如果车辆以高速度行驶在直线与小半径的圆曲线相连的路段,行车是极不舒服.汽车驶近曲线路段时,超高开始,车辆向内侧倾斜,但乘客须维持身体的垂直状态,因为此时未受到离心力的作用.当汽车到达曲线路段时,离心力突然产生,迫使乘客向外倾斜,为了维持平衡,乘客必须迫使自己的身体向内侧倾斜.由于剩余超高发挥作用,乘客须作进一步的姿势的调整.当汽车离开曲线时,上述过程刚好相反.插入缓和曲线后,半径从无穷大逐渐过渡到圆曲线上的某一固定值,离心力逐渐增大,沿缓和曲线心设置超高,离心力平稳逐渐增加,避免了行车颠簸.缓和曲线在铁路上已经使用多年,但在公路上最近才得以应用,这是可以理解的.火车必须遵循精确的运行轨道,采用缓和曲线后,上述那种不舒服的感觉才能消除.然而,汽车司机在公路上可以随意改变侧向位置,通过迂回进入圆曲线来为自己提供缓和曲线.但是在一个车道上有时在其他车道上做这种迂回行驶是非常危险的.设计合理的缓和曲线使得上述迂回没有必要.主要是出于安全原因,公路部门广泛采用了缓和曲线.对于半径相同的圆曲线来说,在未端加上缓和曲线就会改变曲线与直线的相关位置,因此应在最终定线勘测之前应决定是否采用缓和曲线.一般曲线的起点标为PC或BC,终点标为PT或EC.对含有缓和曲线的曲线,通常的标记配置增为:TC、SC、CS和ST.对于双向道路,急弯处应增加路面宽度,这主要基于以下因素:1驾驶员害怕驶出路面边缘;2由于车辆前轮和后轮的行驶轨迹不同,车辆有效横向宽度加大;3车辆前方相对于公路中线倾斜而增加的宽度.对于宽度为24英尺的道路,增加的宽度很小,可以忽略.只有当设计车速为30mile/h,且曲度大于22℃时,加宽可达2英尺.然而,对于较窄的路面,即使是在较平缓的曲线路段上,加宽也是很重要推荐加宽值及加宽设计见公路线形设计2、纵坡线公路的竖向线形及其对车辆运行的安全性和经济性的影响构成了公路设计中最重要的要素之一.竖向线形由直线和竖向抛物线或圆曲线组成,称为纵坡线.纵坡线从水平线逐渐上升时称为坡度变化的影响.在确定坡度时最理想的情况是挖方与填方平衡,没有大量的借方或弃方.所有运土都尽可能下坡运并且距离不长,坡度应随地形而变,并且与既有排水系统的升、降方向一致.在山区,坡度要使得挖填平衡以使总成本最低.在平原或草原地区,坡度与地表近似平行,介是高于地表足够的高度,以利于路面排水,苦有必要,可利用风力来清除表面积雪.如公路接近或沿河流走行,纵坡线的高度由预期洪水位来决定.无论在何种情况下,平缓连续的坡度线要比由短直线段连接短竖曲线构成的不断变向的坡度线好得多.由上坡向下坡变化的路段应设在挖方路段,而由下坡向上坡变化的路段应设在填方路段,这样的线形设计较好,往往可以避免形成与现状地貌相反的圭堆或是凹地.与挖填方平衡相比,在确定纵坡线时,其他考虑则重要得多.城市项目通常比农村项目要求对控制要素进行更详尽的研究,对高程进行更细致地调整.一般来说,设计与现有条件相符的坡度较好,这样可避免一些不必要的花费.在坡度的分析和控制中,坡度对机动车运行费用的影响是最重要的考虑因素之一.坡度增大油耗显然增大,车速就要减慢.一个较为经济的方案则可使坡度减小而增加的年度成本与坡度不减而增加的车辆运行年度成本之间相平衡.这个问题的准确方法取决于对交通流量和交通类型的了解,这只有通过交通调查才能获知.在不同的州,最大纵坡也相差悬殊,AASHTO标准建议由设计车速和地形来选择最大纵坡.现行设计以设计车速为70mile/h时最大纵坡为5%,设计车速30mile/h时,根据地形不同,最大纵坡一般为7%-12%.当采用较长的待续爬坡时,在没有为慢行车辆提供爬坡道时,坡长不能够超过临界坡长.临界坡长可从3%纵坡的1700英尺变化至8%纵坡的500英尺.持续长坡的坡度必须小于公路任何一个断面的最大坡度,通常将长的持续单一纵坡断开,设计成底部为一陡坡,而接近坡顶则让坡度减小.同时还要避免由于断面倾斜而造成的视野受阻.调整公路的最大纵坡为9%只有当路面排水成问题时,如水必须排至边沟或排水沟,最小坡度标准才显示其重要性.这种情况下,AASHTO标准建议最小坡度为%.3、视距为保证行车安全,公路设计必须使得驾驶员视线前方有足够的一段距离,使他们能够避让意外的障碍物,或者安全地超车.视距就是车辆驾驶员前方可见的公路长度.安全视距具有两方面含义:“停车视距”或“不超车视距”或“超车视距”.有时,大件物体也许会掉到路上,会对撞上去的车辆造成严重的危害.同样,轿车或卡车也可能会被一溜车辆阻在车道上.无论是哪种情况发生,合理设计要求驾驶员在一段距离以外就能看见这种险情,并在撞上去之前把车刹住.此外,认为车辆通过离开所行驶的车道就可以躲避危险的想法是不安全的,因为这会导致车辆失控或与另一辆车相撞.停车视距由两部分组成:第一部分是当驾驶员发现障碍物面作出制动之前驶过的一段距离,在这一察觉与反应阶段,车辆以其初始速度行驶;第二部分是驾驶员刹车后车辆所驶过的一段距离.第一部分停车视距取决于车速及驾驶员的察觉时间和制动时间.第二部分停车视距取决于车速、刹车、轮胎、路面的条件以及公路的线形的坡度.在双车道公路上,每间隔一定距离,就应该提供超越慢行车辆的机会.否则,公路容量将降低,事故将增多,因为急燥的驾驶员在不能安全超车时冒着撞车危险强行超车,能被看清的允许安全超车的前方最小距离叫做超车视距.驾驶员在做出是否超车的决定时,必须将前方的能见距离与完成超车动作所需的距离对比考虑.影响他做出决定的因素是开车的小心程度和车辆加速性能.由于人与人的显着差别,主要是人的判断和动作而不是力学定理决定的超车行为随着驾驶员的不同而大不相同.公路是确保交通安全的基础,建设的其他项目都围绕的而展开,因此,在的过程中,如果出现任意的不安全潜在因素,或者低水平的组合,都会影响到整个的质量,并对交通的安全带来不利影响.因此对于的必须予以重点关注.。

桥梁毕业设计外文翻译---混凝土桥的结构处理工具

桥梁毕业设计外文翻译---混凝土桥的结构处理工具

第二部分英文翻译Reliability analysis :a structures management tool for concrete bridgesReinforced concrete structures are susceptible to a variety of deterioration mechanisms, including alkali-thaw action and chloride ingress. Substantial research has been undertaken in relation to these mechanisms and other problems. This has particularly been the case over the last 20 years or so, where the objective has been to identify causes, consequences and develop remediation strategies. This has improved understanding of long-term behaviour of reinforced concrete and resulted in the development of techniques to increase deterioration resistance.At present, the most common approach is to act after a problem has been identified, known as re-active maintenance. This may not be the most economic solution since, in many cases, maintenance is more costly than preventative treatments. However, owners are often reluctant to pay for preventative treatments before deterioration is apparent. Early application of treatments may not be the optimal solution in the long run. Integrated deterioration and performance prediction modeling is essential to pro-actively plan and prioritise inspection, testing and maintenance. This becomes increasingly important as infrastructure ages and justification for maintenance funding becomes increasingly critical.Performance assessment can be achieved through surveys, testing and formal calculations, ideally based on site data that represent, as accurately as possible, the state of the structure. By integrating predictive deterioration models with assessment tools and performance criteria (at element, structure or group level) it becomes possible to base the maintenance regime on time-dependent performance profiles. This is particularly relevant in the context of whole-wife costing procedures.Substantial research has been undertaken in relation to these mechanisms and other problems. This has particularly been the case overthe last 20 years or so, where the objective has been to identify causes, consequences and develop remediation strategies. This has improved understanding of long-term behaviour of reinforced concrete and resulted in the development of techniques to increase deterioration resistance.At present, the most common approach is to act after a problem has been identified, known as re-active maintenance. This may not be the most economic solution since, in many cases, maintenance is more costly than preventative treatments. However, owners are often reluctant to pay for preventative treatments before deterioration is apparent. Early application of treatments may not be the optimal solution in the long run. Integrated deterioration and performance prediction modeling is essential to pro-actively plan and prioritise inspection, testing and maintenance. This becomes increasingly important as infrastructure ages and justification for maintenance funding becomes increasingly critical.Reliability analysis has emerged as an important tool in this multi-objective management process, which must take into account safety, functionality and sustainability criteria. In simple terms, the reliability of a structure or a system is the probability of achieving a particular performance level. Probability or likelihood is the appropriate measure, since all engineering systems are susceptible to uncertainties, arising from random phenomena and incomplete knowledge. Reliability analysis in structural engineering enables quantification of uncertainties associated with loading, materials, deterioration, modeling and other factors. These are integrated into a method that estimates the probability of reaching the specified performance level during the service life of a structure. The method is increasingly being used in bridge engineering, both for calibration of safety levels in codes and standards and improving and refining assessment methodologies. The purpose of this article is to outline its application in managing bridges susceptible to deterioration.Although data for many deterioration variables can be derived from laboratory studies, there is an absence of similar data real structures. Animportant feature of the model is the facility to modify initial predictions, based on published (known as ‘prior’) data, using information and data obtained directly from the actual structures. Reliability analysis is appropriate for this pursose as if it can readily incorporate additional data, updating the probability of reaching a performance target. The concept is analogous to updating the probability of arriving on time whilst on a train, having just obtain some extra information regarding the operating conditions ahead.Typical results produced by the probabilistic deterioration model for a crossbeam chloride exposure zone, similar to the delaminated area shown in Figure 3,are shown in Figure 4.Assuming a threshold of 40% initiation is specified for the first inspection, the model suggests that it should be undertaken after eight years .Assuming that inspection indicates significantly less corrosion initiation (e.g.only about 10%) and attributed, through site investigations, to concrete cover being higher than expected, a revised prediction of the performance profile may be generated .The bridge management actions may then be altered accordingly.Figure 5 illustrates how a limit state profile for this zone changes with assumed conditions. The deterioration model has been integrated with bond limit state equations .Thus, assuming that the component has a target nominal probability of failure of 1×10-5 per year, profile 1 suggests a lifetime of only 17 to 18 years, whereas Profile 2 suggests 30 to 31 years. Both are short lifetimes when compared with the normal life expectancy of bridges. However, initial conditions relating to these results assume that the deck joint has failed from the outset .Alternatively ,the expressions for modelling bond strength may be over-conservative ,as they were developed for intact structures.Substantial research has been undertaken in relation to these mechanisms and other problems. This has particularly been the case over the last 20 years or so, where the objective has been to identify causes, consequences and develop remediation strategies. This has improvedunderstanding of long-term behaviour of reinforced concrete and resulted in the development of techniques to increase deterioration resistance.At present, the most common approach is to act after a problem has been identified, known as re-active maintenance. This may not be the most economic solution since, in many cases, maintenance is more costly than preventative treatments. However, owners are often reluctant to pay for preventative treatments before deterioration is apparent. Early application of treatments may not be the optimal solution in the long run. Integrated deterioration and performance prediction modeling is essential to pro-actively plan and prioritise inspection, testing and maintenance. This becomes increasingly important as infrastructure ages and justification for maintenance funding becomes increasingly critical.Bridge performance criteriaCurrent UKassessment codes are concerned with ultimate limit states (ULS) and do not explicitly require checking of serviceability limit states (ULS). It is assumed that an existing structure has experienced SLS loads during its life. However, the widely accepted SLS criteria of deflection and cracking do not fully take into account the problems posed by deterioration. Deterioration-based criteria such as rust staining, delamination and spalling need to be considered because they clearly influence bridge performance, both functional and financial. These often prove the dominant factor with regard to bridge management strategy.By explicitly considering and specifying performance levels, the engineer is aware of the important deterioration indicators in order to establish the inspection and maintenance regime for the particular structure/member. These performance levels may change over time, due to changes in function, loading, structure importance etc. for example, the relationship between actual and required performance is conceptualized by the diagram shown in Figure 1. Thus, reliability analysis may be used to formulate the probability that performance will exceed that required, thereby estimating the reliability of the structure. The performancemeasure can be related to safety, functionality or any other appropriate criterion.Modeling chloride-induced deteriorationThis particular project concentrated on one specific area of reinforced concrete deterioration, specifically arising from chloride ingress. Chlorides are present in de-icing salts used in the UK during winter. Chloride ions migrate though the concrete, e.g. by absorption and diffusion. Under suitable conditions, they initiate reinforcement bar corrosion. The corrosion mechanism produces rust. The increased volume of the metal, due to the rust, leads to cracking, delamination and spalling of the concrete cover. This results in more rapid and extensive reinforcement corrosion.Reinforced concrete bridge elements located below expansion joints are particularly susceptible to chloride attack if the joint fails. Highway viaducts in the UK typically consist of a reinforced concrete crossbeam directly located below the expansion joint,(see Figure 2).Many crossbeams have suffered severe reinforcement corrosion, delamination and spalling. A typical example is shown in Figure 3, where the reinforcement cover over the crossbeam has delaminated.A probabilistic deterioration model for reinforced concrete bridge components was developed, taking into account the characteristics of these structures and their environment. It assumes that both diffusion and absorption play a part in chlotide migration through the concrete, the variability in the quantity of de-icing salts reaching the crossbeam surface and how these quantities vary annually. Typical chloride exposure zones considered for the crossbeams include the:●Horizontal surface below a failedexpansion joint where water ponding can occur●vertical surface below a failed expansion jointsurfaces below an intact expansion joint, but exposed to traffic spray etc.Although data for many deterioration variables can be derived from laboratory studies, there is an absence of similar data real structures. An important feature of the model is the facility to modify initial predictions, based on published (known as ‘prior’) data, using information and data obtained directly from the actual structures. Reliability analysis is appropriate for this pursose as if it can readily incorporate additional data, updating the probability of reaching a performance target. The concept is analogous to updating the probability of arriving on time whilst on a train, having just obtain some extra information regarding the operating conditions ahead.Typical results produced by the probabilistic deterioration model for a crossbeam chloride exposure zone, similar to the delaminated area shown in Figure 3,are shown in Figure 4.Assuming a threshold of 40% initiation is specified for the first inspection, the model suggests that it should be undertaken after eight years .Assuming that inspection indicates significantly less corrosion initiation (e.g.only about 10%) and attributed, through site investigations, to concrete cover being higher than expected, a revised prediction of the performance profile may be generated .The bridge management actions may then be altered accordingly.Laboratory and site data are essential for improved deterioration modeling and reliability .Much data collection and test interpretations made in the deterioration models. Given the costs associated with maintaining safe, reliable infrastructure systems, this is an area where a concreted effort by industry and organizations could yield substantial benefits.Figure 5 illustrates how a limit state profile for this zone changes with assumed conditions. The deterioration model has been integrated with bond limit state equations .Thus, assuming that the component has a target nominal probability of failure of 1×10-5 per year, profile 1 suggests a lifetime of only 17 to 18 years, whereas Profile 2 suggests 30 to 31 years. Both are short lifetimes when compared with the normal lifeexpectancy of bridges. However, initial conditions relating to these results assume that the deck joint has failed from the outset .Alternatively ,the expressions for modelling bond strength may be over-conservative ,as they were developed for intact structures.Concluding remarksReliability analysis provides a rational and consistent framework for treating uncertainties .It can be a useful management tool with which similar structures can be compared through performance profiles which change over time. The results must be interpreted with care, and stand up to common sense and engineering judgement . Sensitivity analysis is strongly recommended, and can be readily performed.Laboratory and site data are essential for improved deterioration modeling and reliability .Much data collection and test interpretations made in the deterioration models. Given the costs associated with maintaining safe, reliable infrastructure systems, this is an area where a concreted effort by industry and organizations could yield substantial benefits.AcknowledgementsThis work was performed with the support of the Highways Agency. The views expressed are those of the authors and are not necessarily shared by the Highways Agency.可靠性分析——混凝土桥的结构处理工具钢筋混凝土桥结构对多种恶化机制敏感,包括碱趋于和缓行动和氯化物进入。

毕业设计外文文献翻译【范本模板】

毕业设计外文文献翻译【范本模板】

毕业设计(论文)外文资料翻译系别:专业:班级:姓名:学号:外文出处:附件: 1. 原文; 2。

译文2013年03月附件一:A Rapidly Deployable Manipulator SystemChristiaan J。

J。

Paredis, H. Benjamin Brown,Pradeep K. KhoslaAbstract:A rapidly deployable manipulator system combines the flexibility of reconfigurable modular hardware with modular programming tools,allowing the user to rapidly create a manipulator which is custom-tailored for a given task. This article describes two main aspects of such a system,namely,the Reconfigurable Modular Manipulator System (RMMS)hardware and the corresponding control software。

1 IntroductionRobot manipulators can be easily reprogrammed to perform different tasks, yet the range of tasks that can be performed by a manipulator is limited by mechanicalstructure。

Forexample,a manipulator well-suited for precise movement across the top of a table would probably no be capable of lifting heavy objects in the vertical direction. Therefore,to perform a given task,one needs to choose a manipulator with an appropriate mechanical structure.We propose the concept of a rapidly deployable manipulator system to address the above mentioned shortcomings of fixed configuration manipulators。

土木专业毕业设计外文翻译英文文献

土木专业毕业设计外文翻译英文文献

144 Study on Construction Cost of Construction ProjectsHui LiAudit Department of Tianjin Polytechnic UniversityE-mail: lihui650122@AbstractChina is a country which has the largest investment amount in engineering construction in the world and which has the most construction projects. It is a significant subject for the extensive engineering managers to have effective engineering cost management in construction project management and to reasonably determine and control construction cost on the condition of ensuring construction quality and time limit.On the basis of the status quo of losing control in Chinese construction investment and of separation of technique and economy in engineering, and guided by basic theories of construction cost control, the author discusses control methods and application of construction cost, sets forth existing issues in construction cost control and influences of these issues on determination and control of construction cost, puts forward that construction cost control should reflect cost control of the entire construction process at the earlier stage of construction, and then introduces some procedures and methods of applying value project cost control at all stages of construction projects.Keywords: Construction cost, Cost control, Project1. Significance of the studyThe existing construction cost management system in China was formulated in 1950s, and improved in 1980s. Traditional construction cost managerial approach was one method brought in from the former Soviet Union based on unified quota of the country. It is characterized by the managerial approach of construction cost in the planned economy, which determines that it cannot adapt to requirements of the current market economy.Traditional construction cost managerial approach in China mainly includes two aspects, namely, determination approach of construction cost and control approach of construction cost. The traditional determination approach of construction cost mainly applied mechanically national or local unified quantity quota to determine the cost of a construction project. Although this approach has undergone reform of over 20 years, until now, influences of planned economy management mode have still been in existence in many regions. Control approach of our traditional construction cost is mainly to control settlement and alteration of construction cost, which is merely an approach to settle accounts after the event, and which cannot satisfy the purpose of saving resources and improving work. In recent years, requirements of developed countries on project investment have been to plan to control in advance and to control in the middle of an event, whose effects have proved to be effective. An actually scientific approach should be that construction cost control approach beforehand and after the event can eliminate or diminish labour in vain or poor efficiency and unnecessary resource degradation and methods applied in implementation of construction projects before or after the event.Considering the above situation, the academic circles put forward concept of cost management and control of the overall process as early as 1980s. They began to attach importance to prophase management of construction projects and take the initiative to conduct cost management. Afterwards, on July 1, 2003, implementation of <<Cost Estimate Norm for Bill of Quantity of Construction Works>> symbolized that cost estimate of China had entered a brand-new era that complied with development rules of market economy. From then on, concepts and approaches of Chinese cost management were really integrated with the international society.Losing control of construction project investment is a universal phenomenon in fixed investment field in China. A construction project consumes quite a lot of manpower, materials and machines, with large investment, long construction cycle, and strong synthesis, so it is related with economic interests of all construction parties and means a lot to national economy. Currently, in the field of Chinese project construction, there exists the status quo of separation of technique and economy. Most of engineers and technicians tend to regard construction cost as duty of financing andpreliminary budget personnel, and mistakenly believe that it has nothing to do with themselves. In the process of carrying out a project, they usually only focus on quality control and progress control, while they ignore control over investment in construction projects. If technicians ignore construction cost, and those who are in charge of construction cost have no knowledge in relevant technical construction connected with construction cost, then it is difficult for them to reasonably confirm and effectively control construction cost. Construction supervision investment control refers to managerial activities at the whole implementation state of the project, which attempts to guarantee realization of project investment targets with the premise of satisfying quality and progress. Investment targets are set at different stages with further progress of construction practice, and construction cost control runs through the entire process of project construction, but it should give prominence to the key points. Obviously, the key of construction cost control lies in investment decision-making and design stage before the construction, while after the investment decision is made, the key lies in the design. Life cycle of construction project includes construction cost and recurrent expenditure after the construction project is put into service, and discard and removal costs etc after usage period of the project. According to analysis of some western countries, usually design cost only amounts to less than 1% of life cycle of construction project. However, it is the cost of less than 1% that accounts for more than 75% of influences on construction cost. It is therefore obvious that, design quality is vital to benefits of the entire project construction.For a long time, construction cost control of the preliminary engineering of project construction has been ignored in China, while the primary energy of controlling construction cost has been focused upon auditing working drawing estimate, settling construction cost and settling itemized account during construction. Although this has its effect, after all, this had no difference from taking precautions after suffering a loss and getting half the result with twice the efforts. In order to effectively control construction cost, the emphasis of control should be firmly transferred to preliminary construction stage. At present, we should take all pains to grasp this significant stage so as to achieve maximum results with little effort.This article aims to analyze existing issues in cost control of the entire construction period through study on theoretical methods and practice of construction cost management. Especially, issues in cost control in the earlier period of construction deserve our research, so that we can explore corresponding reform measures to offer some references for construction project cost control.The situation of a construction project in which budgetary estimate exceeds estimation, budget exceeds budgetary estimate, and settlement exceeds budget, is a universal phenomenon in investment in fixed assets in China. Construction cost which is out of control adds to investment pressure, increases construction cost, reduces investment profit, affects investment decision-making, and, to a great extent, wastes the national finance, so it is likely to result in corruption or offence. Since the middle of 1950s, on the basis of summarizing practical experiences of fundamental construction battle line for several decades, we have conducted a series of reforms in construction field. Especially since May 1988, we have gradually implemented the system of construction supervision all over the country, which has had some positive effects upon reversing the phenomenon of losing control of a construction project in the implementation period. However, because that system is still in its starting stage, there hasn’t appeared a large batch of professional and socialized supervision teams. In addition, in projects in which construction supervision is carried out, there exist general phenomena, such as “emphasis on quality control at the construction stage and neglect of investment control”, and “emphasis on technical aspects of supervision and neglect of economic aspects of supervision”. In reality, rights of supervision tend to be confined to management of technical aspects, while management of economic aspects is firmly in control of proprietors. Meanwhile, lagging behind of existing construction cost management system is the primary cause for losing control of construction cost. Therefore, as a whole, the phenomenon of losing control over construction project cost is still quite serious, so it is necessary to conduct further study and make further analysis on major factors of current construction cost management and factors at all stages of a construction project that affect construction cost.2. Primary study contentAiming at the subject of “control of whole-process of construction project cost”, and based on lots of literature reviews about determination and control of construction project cost both at home and abroad, the author of this paper has collected extensively some relevant provincial and city reports and data after investigation. Afterwards, the author conducts the following work.1) To analyze formulation of construction project investment and to find out primary reasons for losing control over construction cost at all stages of a construction project.2) To study and analyze status quo and existing issues of current construction cost management, and study influences of these issues upon determination and control of a construction cost.3) To put forward effective approaches and methods as well application of value engineering of a construction project from its decision-making stage, design stage, construction stage to the final acceptance of construction stage.1454) To make clear significance, necessity and feasibility of cost control of a construction project so as to provide recommendations for improvement of construction cost management in China.2.1 Construction cost control theory and management mod eAccording to the new cost control theory, cost engineers are “professional persons who undertake cost estimate, cost control, marketing planning and scientific management”. Fields undertaken by cost engineers include such aspects as project management, project planning, progress management and profitability analysis etc of a project construction and its production process. Cost engineers offer service for control over life cycle expenditure, property facilities and production & manufacture of a construction project with their management technique with an overall cost.2.2 Current construction cost management model and theories in China2.2.1 Direct regulation and control of the governmentConsidering development process of quota, it can be discovered that quota has come into being, developed and become mature gradually with development of planned economy after foundation of PRC. Since China has carried out centralized management model of investment system for a long time, the government is not only a maker of macropolicy, but a participant of micro-project construction. Therefore, a unified quota with dense colour of planned economy is able to provide powerful methods and means for the government to carry out macro-investment regulation and control and micro-construction project management.2.2.2 Valuation basis for current construction costBasic materials for calculation of construction cost usually include construction cost quota, construction cost expense quota, cost index, basic unit price, quantities calculation rule and relevant economic rules and policies issued by competent departments of the government, etc. It includes index of estimate (budgetary estimate index), budgetary estimate quota, budgetary quota (comprehensive budgetary quota), expense quota (standard), labor quota, working-day norm, materials, budgetary price of facilities, direct price index of a project, material price index and cost index. And also included is valuation criterion of consumption quota and list of items in recent two years.2.2.3 Valuation model of current construction costValuation model is a basic aspect of construction cost management. Construction cost management is a governmental behavior, while valuation model is a means for a country to manage and control construction cost. There are two construction valuation models at present in China, namely, valuation model according to quota and one according to bill of quantities.2.2.3.1 Valuation model according to quotaValuation model according to quota is an effective model adopted during the transition period from planned economy to market economy. Determination of construction cost through valuation model according to quota prevents overrated valuation and standards and prices pressed down to some extent, because budgetary quota standardizes rate of consumption and a variety of documents stipulate manpower, materials, unit price of machines and all sorts of service fee norms, which reflects normativity, unitarity and rationality of construction cost. However, it has an inhibited effect upon market competition, and is not favorable for a construction enterprise to improve its technique, strengthen its management and enhance its labor efficiency and market competition.2.2.3.2 Valuation model according to bill of quantitiesValuation model according to bill of quantities is a construction cost determination model proposed recently. In this model, the government merely unifies project code, project name, unit of measurement and measurement rule of quantities. Each construction enterprise has its self-determination to quote a price according to its own situation in a tender offer, and price of building products is formed thereby in the process of bidding.2.3 Cost control in the process of implementationFor a long time, technique and economy has been separated in the field of project construction. Restrained by the planned economy, there lacks the economic concept in the minds of our engineers and technicians, because they regard reduction of construction cost as a duty of financial personnel which has nothing to do with themselves. However, the primary responsibility of financial and preliminary budget personnel is to act in accordance with financial system. Usually, they are not familiar with construction technique, and know little or even nothing about changes of various relations in project design, construction content and implementation of construction. Under such a circumstance, they have no choice but to mechanically work out or audit the expenditure from a financial perspective, which results in mutual separation of technique and economy. They just do what they do, which negatively reflects price of quantities of a project that has been completed, so it is difficult to control construction cost rationally and effectively.1462.4 Control of cost in the process of constructionImplementation stage of a construction project is a stage which requires the most assets in the whole process of a project construction, and is also a vital stage for pecuniary resources to transform into building entities. Cost control at the implementation stage refers to confine construction cost within a scheduled control scope through a scientific cost control theory and method on the condition of ensuring project quality and time limit. The process of generation of a building entity is inreversible, so if effective automatic control and precontrol cannot be conducted over construction cost, then economic loss might be caused that cannot be made up for.2.5 Analysis of major factors that affect construction cost at the stage of implementationImplementation stage of a project refers to the period from completion of construction documents design and examination and submission to the construction party to the final completion acceptance of the project and until it is put into use. According to the basic operation procedure of the implementation stage of a construction project, formation of a construction cost has to undergo such major aspects as bidding, contract signing and management, joint auditing of a shop drawing, investigation of a construction management plan, material management and completion settlement, etc. All these aspects affect construction cost settlement to different degrees. In that process, after evolving from budgetary price, price for successful bidding, refurbishing cost for a contract, the construction cost is finally determined in the form of settlement price for project completion. Factors affecting construction cost are various, but from the perspective of analysis of cost formation, there are primarily the following reasons.1) Influences of a project bidding. Bidding can determine price for successful bidding, while contract price is determined on the basis of price for successful bidding. If something goes wrong with bidding, then it might result in distortion of the price for bidding, and it is impossible to provide accurate and reliable foundation for cost control, and even result in losing control over the cost.2) Influences of contract signing and management. Determination of a contract price further makes precise target of cost control, and an initial draft of a contract term provides correct foundation and principles for cost control. After signing of a contract, contract items are regarded as foundation, which will have strict contract control over design changes at the construction stage, project measurement, payment of a construction debt, and construction compensation, etc, and which will ensure realization of a control target. Therefore, losing control over signing and management of a contract will necessarily result in losing control over construction cost.3) Influences of examination of construction management plan. Construction management plan is one of important foundations for determine a project bidding price and contract price. In the process of construction, adjustment of a contract price should also be determined according to construction management plan, because quality of construction management plan will directly affect quality and progress of a project. Therefore, losing control over examination of construction management plan will bring extremely unfavorable influences upon control over construction cost.4) Influences of material management. On one hand, material price is an important component of bidding price and contract price. On the other hand, material expense accounts for a large proportion in construction cost, because price of materials determine construction cost. Therefore, losing control over material management will necessarily result in losing control over construction cost.5) Influences of settlement, examination and verification of a project completion. Settlement, examination and verification is the final stage of a construction cost control at the implementation stage. A strict and meticulous settlement, examination and verification can ensure accuracy and authenticity of settlement cost of a project. According to previous analysis, we believe that all aspects of cost control can have effect upon formation of construction cost, among which bidding of a project, contract signing and management, examination of a construction management plan and management of materials all have decisive effects upon formation of construction cost, and are vital aspects in cost construction at the implementation stage of a project, so neglect of these four aspects is a direct cause for losing control over construction cost.In this paper, the author summarizes relevant issues in construction cost control at the decision-making stage of a construction project, at the design stage and construction stage, and puts forward principles or resolutions for handing such issues. Especially, as a method of combination of technique and economics, application of value engineering is elaborated at all stages, so that construction cost gets effective controlled. This paper cannot conclude all such issues existing, and also resolutions to resolve these issues cannot cover and contain everything, but with development of construction, new issues and new trains of thought will continue to emerge.ReferencesAminan Fayek. (1998). Competitive Bidding Strategy Model and Software System for Bid Preparation. Jounal of Construction Engineering and Management.Chen, Jianguo. (2001). Project Measurement and cost management. Shanghai: Tongji University Press.147Don R.Hansen & Maryanne M. Mowen. (2005). Cost Management: Accounting and Control.Dong, Shibo. (2003). Status Quo of Construction Cost Management Theory and Its Developmental Trend. Construction Cost Management, (5).Feng, Jingchun. (2000). Study on Counter Measures of Project Cost Management. Technical and Economic Development, (6).George J.Ritz. (1993). Total Construction Project Management.Gou, Zhiyuan. (2002). Thought on Integrated Control Approach of Construction Cost Management. Construction Cost Management, (6).Hao, Jianxin. (2002). American Construction Cost Management. Tianjin: Nankai University Press, 1, 51.Hu, Jianming. (2002). Discussion on Construction Cost Estimation Consultant Participating in Whole Course of Cost Management. Construction Cost Management, (5).Hu, Zhifeng. (2000). Overall Process Control on Construction Projects. Coal Enterprise Management, (7).Huang, Yonggen. (2004). Value Engineering and Its Application in Construction Cost Control. Construction Economics, (8).Ivor H Seeley. (1996). Building economics (fourth edition). Macmillan Press LTD.James A.Bent & Kenneth King Humphreys. (1996). Effective Project Management through Applied Cost and Schedule Control, Cost Engineering.Jan Emblemsavg. (2003). Life cycle Costing: sing Activity-based Costing and Monte Carlo Methods to Manage Future Costs and Risks. John wiley & sons, (5).Janice T. Dana. (1999). Standardized Quantity Recipe File for Quality and Cost Control.John E.Schaufelberger & Len Holm. (2001). Management of Construction Projects: A Constructor's Perspective.John Innes, Falconer Mitchell & Takeo Yoshikawa. (2000). Activity Costing for Engineers. Research Studies Press Ltd. John R.Canada, William G Sullivan, Dennis 3. Kulonda & John A.White. (2004). Capital Investment Analysis for Engineering and Management.Li, Tinggui. (2003). Study on Cost Management Model and Countermeasures of Construction project after China's entry into the WTO. Construction Cost Management.Liu, Guiwen & Shen, Qiping. (2001). A Study of Value Engineering Applications in China’s Construction Industry. Value Engineering, (3).Liu, Hongqing. (2003). About overall cost control. Shanxi Architecture, (29)6.Liu, Zhongying & Mao, Jian. Architecture Project Quantity List Quotation. Southeast University Press, 9.Luo, Dinglin. (1997). Determination and Control of Construction Project Cost at Home and Abroad. Beijing: Chemical Industry Press.Ma, Guanghong & Xu, Wei. (2003). Discussion on Application of Overall Cost Management Theory. Project Management, (4).Ma, Guanghong & Xu, Wei. (2003). Discussion on Application of Overall Cost Management Theory. Project Management, (4).Norton B R & McElligot C W. (1995). Value management in construction: a practical guide. Hampshire: Macmillan Press.Paul J. McVety. (1997). The Menu and the Cycle of Cost Control.Project Management Institute. (2004). A Guide to the Project Management Body of Knowledge.Qi, Anbang. (2000). Total Cost Management for Engineering Project. Tianjin: Nankai University Press.Qin, Aiguo. (1999). Study on Construction Cost Management. Economic Tribune, (22).Ren, Guoqiang & Yin, Yilin. (2003). The Feasibility Study on Life Cycle Cost Management in Terms of Paradigm Transformation. China Soft Science Magazine, (5).Ren, Hong. (2004). Cost Planning and Control of Construction Project. China Higher Education Press.Sidney M.Levy. (2002). Project Management in Construction.Stephen P Robbins & David A. Decenzo. (2002). Fundament of Management. Prentice Hall, Inc.148Takashi Ishikawa. (1996). Analogy by Abstraction: Case Retrieval and Adaptation for Inventive Design Expert Systems. Expert Systems with Application, (4)10.Tao, Xueming, Huang, Yunde & Xiong, Wei. (2004). Construction Cost Valuation and Management. China Architecture & Building Press, 2.Wang, Ailin. (2003). Value Engineering and Its Application in Constructional Engineering. Anhui Architecture, (5). Wang, Li & Xu, Zihua. (2004). Comparative Study on Construction Cost Models at Home and Abroad. Architecture Economics.Wang, Yulong. (1997). 2000 Cases on Issues of Construction Project Cost. Shanghai: Tongji University Press. Wang, Zhenqiang. (2002). British Construction Cost Management. Tianjin: Nankai University Press.Wang, Zhenqiang. (2002). Japanese Construction Cost Management. Tianjin: Nankai University Press, 4.Xiang, Ke & Luo, Feng. (2004). Cost Control of Design Stage. Sichuan Architecture, (2).Xu, Datu. (1997). Determination and Control of Construction Cost. Beijing: China Planning Press.Xu, Datu. (1997). Investment Control of Construction Project. Beijing: China Planning Press.Yin, Yilin. (2001). Determination and Control of Construction Cost. Beijing: China Planning Press.Zhang, Caijiang, Li, Kehua & Xu, Yongmei. Review of VE Theory and Practice in China and Some Deep Thinking about its Depression. Nankai Business Review, (1).Zhong, Guangen. (2004). Brief Discussion on Cost Control System in Projects of Commonwealth Nations.Zuo, Jin & Han, Hongyun. Actuality & Amelioration of Whole Life-cycle Value-chain in Architecture. Value Engineering, (6).149。

大跨度桥梁的外文翻译

大跨度桥梁的外文翻译

本科毕业设计外文翻译大跨度桥梁1.悬索桥悬索桥是现行的跨径超过600m大桥的唯一解决方案,而且对跨径在300m以上的桥梁它也是被认为是一种很有竞争力的方案。

现在世界上最大跨径的桥梁是纽约的威拉查诺(Verrazano)海峡大桥,另一个是英国的塞温(Savern)大桥。

悬索桥的组成部分有:柔性,主塔,锚碇,吊索(挂索),桥面板和加劲桁架。

主缆是有一组平行的单根高强钢丝在现场扭在一起并绑扎成型的钢丝束组成的。

每根钢丝都是经过渡锌处理的,并且整个用保护层覆盖着。

所用的钢丝应该是冷拔钢丝而不是经过热处理的各种钢丝。

在进行主塔设计时应该特别注意其在美学上的要求。

主塔很高而且具有足够的柔性,使其每一座塔顶都可认为是与主缆铰接。

主缆的两端很安全的锚固在非常坚实的锚碇上。

吊索把桥面板上的荷载传递到主主缆上。

吊索也是有高强钢丝制成的而且通常是竖直的。

桥面板通常是有加劲钢板,肋或槽型板,横梁制成的异性结构。

提供一些加劲梁连接在其主塔之间,能够起到控制空气动力运动并限制桥面板局部倾角变化。

如果加劲系统不适当,由于风引起的竖向振动也许会导致结构倾斜,就像塔科玛(Tacoma)海峡大桥的悲剧性的破坏所表明的那样。

边跨与主跨的跨径比的变化范围是0.17~0.50。

在现有的采用加劲梁的桥梁上,当跨径高大1000米时跨径与桥梁的建筑高度之比为85与100之间。

现有的桥梁的跨径与桥面板宽度之比约为20~56。

桥梁结构的空气动力稳定性必须得通过对其模型的风洞试验及细部分析进行全面的研究。

2.斜拉桥体系在过去的十年间,斜拉桥得以广泛的应用,尤其实在欧洲,而在世界其它地区,应用相对少一些。

在现代桥梁工程中,斜拉桥体系的重新兴旺起来是由于欧洲(主要是德国)的桥梁工程师有一种趋势,即从因为战争而短缺的材料上获得最佳的结构性能。

斜拉桥是有按各向异性桥面板和由吊索支撑的连续梁构成的体系建造起来的,这些吊索是一些穿过或固定的位于主桥墩的索塔顶上的倾斜主缆。

土木工程-毕业设计-论文-外文翻译-中英文对照

土木工程-毕业设计-论文-外文翻译-中英文对照

英文原文:Concrete structure reinforcement designSheyanb oⅠWangchenji aⅡⅠFoundation Engineering Co., Ltd. Heilongjiang DongyuⅡHeilongjiang Province, East Building Foundation Engineering Co., Ltd. CoalAbstract:structure in the long-term natural environment and under the use environment's function, its function is weaken inevitably gradually, our structural engineering's duty not just must finish the building earlier period the project work, but must be able the science appraisal structure damage objective law and the degree, and adopts the effective method guarantee structure the security use, that the structure reinforcement will become an important work. What may foresee will be the 21st century, the human building also by the concrete structure, the steel structure, the bricking-up structure and so on primarily, the present stage I will think us in the structure reinforcement this aspect research should also take this as the main breakthrough direction.Key word:Concrete structure reinforcement bricking-up structure reinforcement steel structure reinforcement1 Concrete structure reinforcementConcrete structure's reinforcement divides into the direct reinforcement and reinforces two kinds indirectly, when the design may act according to the actual condition and the operation requirements choice being suitable method and the necessary technology.1.1the direct reinforcement's general method1)Enlarges the section reinforcement lawAdds the concretes cast-in-place level in the reinforced concrete member in bending compression zone, may increase the section effective height, the expansion cross sectional area, thus enhances the component right section anti-curved, the oblique section anti-cuts ability and the section rigidity, plays the reinforcement reinforcement the role.In the suitable muscle scope, the concretes change curved the component right section supporting capacity increase along with the area of reinforcement and the intensity enhance. In the original component right section ratio of reinforcement not too high situation, increases the main reinforcement area to be possible to propose the plateau component right section anti-curved supporting capacity effectively. Is pulled in the section the area to add the cast-in-place concrete jacket to increase the component section, through new Canada partial and original component joint work, but enhances the component supporting capacity effectively, improvement normal operational performance.Enlarges the section reinforcement law construction craft simply, compatible, and has the mature design and the construction experience; Is suitable in Liang, the board, the column, the wall and the general structure concretes reinforcement; But scene construction's wet operating time is long, to produces has certain influence with the life, and after reinforcing the building clearance has certain reduction.2) Replacement concretes reinforcement lawThis law's merit with enlarges the method of sections to be close, and after reinforcing, does not affect building's clearance, but similar existence construction wet operating time long shortcoming; Is suitable somewhat low or has concretes carrier's and so on serious defect Liang, column in the compression zone concretes intensity reinforcement.3) the caking outsourcing section reinforcement lawOutside the Baotou Steel Factory reinforcement is wraps in the section or the steel plate is reinforced component's outside, outside the Baotou Steel Factory reinforces reinforced concrete Liang to use the wet outsourcing law generally, namely uses the epoxy resinification to be in the milk and so on methods with to reinforce the section the construction commission to cake a whole, after the reinforcement component, because is pulled with the compressed steel cross sectional area large scale enhancement, therefore right section supporting capacity and section rigidity large scale enhancement.This law also said that the wet outside Baotou Steel Factory reinforcement law, the stress is reliable, the construction is simple, the scene work load is small, but is big with the steel quantity, and uses in above not suitably 600C in the non-protection's situation the high temperature place; Is suitable does not allow in the use obviously to increase the original component section size, but requests to sharpen its bearing capacity large scale the concrete structure reinforcement.4) Sticks the steel reinforcement lawOutside the reinforced concrete member in bending sticks the steel reinforcement is (right section is pulled in the component supporting capacity insufficient sector area, right section compression zone or oblique section) the superficial glue steel plate, like this may enhance is reinforced component's supporting capacity, and constructs conveniently.This law construction is fast, the scene not wet work or only has the plastering and so on few wet works, to produces is small with the life influence, and after reinforcing, is not remarkable to the original structure outward appearance and the original clearance affects, but the reinforcement effect is decided to a great extent by the gummy craft and the operational level; Is suitable in the withstanding static function, and is in the normal humidity environment to bend or the tension member reinforcement.5) Glue fibre reinforcement plastic reinforcement lawOutside pastes the textile fiber reinforcement is pastes with the cementing material the fibre reinforcement compound materials in is reinforced the component to pull the region, causes it with to reinforce the section joint work, achieves sharpens the component bearing capacity the goal. Besides has glues the steel plate similar merit, but also has anticorrosive muddy, bears moistly, does not increase the self-weight of structure nearly, durably, the maintenance cost low status merit, but needs special fire protection processing, is suitable in each kind of stress nature concrete structure component and the general construction.This law's good and bad points with enlarge the method of sections to be close; Is suitable reinforcement which is insufficient in the concrete structure component oblique section supporting capacity, or must exert the crosswise binding force to the compressional member the situation.6) Reeling lawThis law's good and bad points with enlarge the method of sections to be close; Is suitable reinforcement which is insufficient in the concrete structure component oblique section supporting capacity, or must exert the crosswise binding force to the compressional member the situation.7) Fang bolt anchor lawThis law is suitable in the concretes intensity rank is the C20~C60 concretes load-bearing member transformation, the reinforcement; It is not suitable for already the above structure which and the light quality structure makes decent seriously. 1.2The indirect reinforcement's general method1)Pre-stressed reinforcement law(1)Thepre-stressed horizontal tension bar reinforces concretes member in bending,because the pre-stressed and increases the exterior load the combined action, in the tension bar has the axial tension, this strength eccentric transmits on the component through the pole end anchor (, when tension bar and Liang board bottom surface close fitting, tension bar can look for tune together with component, this fashion has partial pressures to transmit directly for component bottom surface), has the eccentric compression function in the component, this function has overcome the bending moment which outside the part the load produces, reduced outside the load effect, thus sharpened component's anti-curved ability. At the same time, because the tension bar passes to component's pressure function, the component crack development can alleviate, the control, the oblique section anti-to cut the supporting capacity also along with it enhancement.As a result of the horizontal lifting stem's function, the original component's section stress characteristic by received bends turned the eccentric compression, therefore, after the reinforcement, component's supporting capacity was mainly decided in bends under the condition the original component's supporting capacity 。

建筑工程毕业设计外文翻译英文原文

建筑工程毕业设计外文翻译英文原文

建筑工程毕业设计外文翻译英文原文The effects of surface preparation on the fracture behavior ofECC/concrete repair systemToshiro Kamada a,*, Victor C. Li ba Department of Civil Engineering, Gifu University, Yanagido, Gifu 501-1193, Japanb Advanced Civil Engineering Materials Research Laboratory, Department of Civil and Environmental Engineering,University of Michigan, Ann Arbor, Michigan, MI 48109-2125, USAReceived 7 July 1999; accepted 15 May 2000AbstractThis paper presents the influence of surface preparation on thekink-crack trapping mechanism of engineered cementitious composite (ECC)/concrete repair system. In general,surfacepreparation of the substrate concrete is considered essential to achieve a durable repair. In thisexperiment, the ``smooth sur face’’ system showed more desirable behavior in the crack pattern and the crack widths than the ``rough surface’’ system. This demonstrates that the smooth surface system is preferable to the rough surface system, from the view point of obtaining durable repair structure. The special phenomenon of kink-crack trapping which prevents the typical failuremodes of delamination or spalling in repaired systems is best revealed when the substrate concrete is prepared to have a smooth surface prior to repair. This is in contrast to the standard approach when the substrate concrete is deliberately roughened to create better bonding to the new concrete. Ó 2000 Elsevier Science Ltd. All rights reserved.Keywords: ECC repair system; Kink-crack trapping mechanism; Surface preparation; Durable repair1. IntroductionEngineered cementitious composites (ECCs) [1,2] are high performance fiber-reinforced cement based composite materials designed with micromechanical principles. Micromechanicalparameters associated with fiber, matrix and interface are combined to satisfy a pair of criteria, the first crack stress criterion and steady state cracking criterion [3] to achieve the strain hardening behavior. Micromechanics allows optimization of the composite for high performance while minimizing the amount of reinforcing fibers (generally less than 2-3%). ECC has a tensile strain capacity of up to 6% and exhibits pseudo-strain hardening behavior accompanied by multiple cracking. It also has high ultimate tensile strength (5-10 MPa), modulus of rupture (8-25 MPa), fracture toughness (25-30 kJ/m2) and compressive strength (up to 80 MPa) and strain (0.6%). A typical tensile stress-strain curve is shown in Fig. 1. ECC has its uniqueness not only insuperior mechanical properties in tension or in relatively small amount ofchopped fiber usage but also in micromechanical methodology in material design.The use of ECC for concrete repair was proposed by Li et al. [4], and Lim and Li [5]. In theseexperiments, specimens representative of an actual repair system - bonded overlay of a concrete pavement above a joint, were used. It was shown that the common failure phenomenona ofspalling or delamination in repaired concrete systems were eliminated. Instead, microcracksemanated from the tips of defects on the ECC/concrete interface, kinked into and subsequently were arrested in the ECC material (see Fig. 2, [5]). The tendency for the interface crack to kink into the ECC material depends on the competing driving force for crack extension at differentorientations, and on the competing crack extension resistance along the interface and into the ECC material. A low initial toughness of ECC combined with a high Mode II loading configuration tends to favor kinking. However, if the toughness of ECC remains low after crack kinking, this crack will propagate unstably to the surface, forming a surface spall. This is the typically observed phenomenon associated with brittle concrete and even fiber-reinforced concrete (FRC). In the case of ECC, the kinked crack is trapped or arrested in the ECC material, dueto the rapidly rising toughness of the ECC material. Conceptually, the ECC behaves like a material with strong R-curve behavior, with lowinitial toughness similar to that of cement (0.01 kJ/m2) and high plateau toughness (25-30 kJ/m2). After kinked crack arrest,additional load can drive further crackextension into the interface, followed by subsequent kinking and arrest.Details of the energetics of kink-crack trapping mechanism can befound in [5]. It was pointed out that this kink-crack trapping mechanism could serve as a means for enhancing repaired concrete system durability.In standard concrete repair, surface preparation of the substrate concrete is considered critical in achieving a durable repair [6]. Inthe study of Lim and Li [5], the ECC is cast onto a diamond saw cut surface of the concrete. Hence, the concrete surface is smooth and is expected as a result to produce a low toughness interface. Higherinterface roughness has been associated with higher interface toughnessin bi-material systems [7].In this paper, this particular aspect of the influence of surface preparation on the kink-crack trapping phenomenon is investigated. Specifically, the base concrete surfaces were prepared by threedifferent methods. The first surface was obtained as cut surface byusing a diamond saw (smooth surface), similar to that used in theprevious study [5]. The second one was obtained by applying a lubricanton the smooth surface of the concrete to decrease the bond between thebase concrete and the repair material. This surface was applied only in one test case to examine the effect of weak bond of interface on the fracture behavior of the repaired specimen. The third surface was prepared with a portable scarifier to produce a roughened surface (rough surface) from a diamond saw-cut surface.Regarding the repair materials, the water/cement ratio of ECC was varied to control its toughness and strength. Thus, two different mixtures of ECC were used for the comparison of fracture behavior in both smooth and rough surface case. Concrete and steel fiber-reinforced concrete (SFRC) were also used as control repair materials instead of ECC.2. Experimental procedure2.1. Specimens and test methodsThe specimens in this experiment were designed to induce a defect in the form of aninterfacial crack between the repair material and the base concrete, as well as a joint in thesubstrate. Fig. 3 shows the dimensions of the designed specimen and the loading configuration, and these were the same as those of the previous experiment [5]. This loading condition can provide a stable interface crack propagation condition, when the crack propagates along the interface [8].In this experiment, concrete, SFRC and ECC (with two different W/C ratios) were used as therepair materials. Table 1 illustrates the combinations of the repair material and the surface condition of test specimens. The numbers of specimens are also shown in Table 1. Only in the concrete overlay specimens, a special case where lubricant was smeared on the concrete smooth surface was used.The mix proportions of materials are shown in Table 2. Ordinary mixture proportions wereadopted in concrete and SFRC as controls for comparisons with ECC overlay specimens. The steel fiber for SFRC was ``I.S fiber’’, straight with indented surfaceand rectangular cross-section (0.5* 0.5 mm2), 30 mm in length. An investigation using a steel fiber with hooked ends had already been performed in the previous study [5]. Polyethylene fiber (Trade name Spectra 900) with 19 mm length and 0.038 mm diameter was used for ECC. The elastic modulus, the tensile strength and the fiber density of Spectra 900 were 120 GPa, 2700 MPa and 0.98 g/cm3, respectively. Two different ECCs were used with different water/cement ratios. The mechanical properties of the base concrete and the repair materials are shown in Table 3. The tensile strain capacity of the ECC materials are not measured, but are estimated to be in excess of 3% based on test results of similar materials [2].An MTS machine was used for loading. Load and load point displacement were recorded. The loading rate in this experiment was0.005 mm/s. After the final failure of specimens, interface crack (extension) lengths were measured at both (left and right) sides of a specimen as the distance from a initial notch tip to a propagated crack tip along the interface between the base concrete and the repair material.2.2. Specimen preparationMost of the specimen preparation procedures followed those of the previous work [5]. The base concrete was prepared by cutting a concrete block (see Fig. 4(a)) into four pieces (see Fig. 4(b)) using a diamond saw. Two out of the four pieces were usedfor one smooth surface repairspecimen. In order to make a rough surface, a cut surface was roughened uniformly with ascarifier for 30 s. To prepare a repair specimen in the form of an overlay system, a repair material was cast against either the smooth surface or the rough surface of the base concrete blocks (see Fig. 5). Special attention was paid both to maintain cleanliness and to provide adequate moisture on the base concrete surface just before the casting. In two of the concrete overlay specimens, lubricant was sprayed on the smooth surface just before concrete casting. The initial notch and joint were made by applying a smooth tape on the base concrete before casting the repair materials(see Fig. 4(c)).The specimens were cured for 4 weeks in water. Eventually, the base concrete was cured for a total of 8 weeks, and repair materials were cured for 4 weeks in water. The specimens were dried for 24 h before testing.3. Results and discussion3.1. Comparison of the ECC overlay system with the control systemsFig. 6 shows the representative load-deflection curves in each test case. The overall peak load and deflection at peak load are recorded in Table 4. In the ECC overlay system, the deflections at peak load, which reflect the system ductility, are considerably larger than those of both theconcrete overlay (about one order of magnitude higher) and the SFRC overlay system (over five times). These results show good agreement with the previous results [5]. Moreover, it is clear fromFig. 6 that the energy absorption capacity in the ECC overlay system is much enhanced when it is compared with the other systems. This significant improvement in ductility and in energyabsorption capacity of the ECC overlay system is expected to enhance the durability of repaired structures by resisting brittle failure. The ECC overlay system failed without spalling ordelamination of the interface, whereas, both the concrete and SFRC overlay systems failed by spalling in these experiments (Fig. 7).3.2. Influence of surface preparationBoth in the concrete overlay system and the SFRC overlay system, the peak load and thedeflection at peak load do not show significant differences between smooth surface specimen and rough surface specimen (Table 4). Thetypical failure mode for both overlay systems (for smooth surface) is shown in Fig. 7. In the concrete overlay specimen with lubricant on the interface, delamination between repair concrete and substrate occurred first, followed by a kinked crack which propagates unstably to the surface of the repair concrete. On the other hand, in the concrete overlay system without lubricant, the initial interface crack kinked out from the interface into the repair concrete with a sudden load drop, without any interface delamination. The fractured halves of the specimens separated completely in both smooth surface specimens and rough surfacespecimens. In the SFRC overlay system, the initial interface crack also kinked out into the SFRC and the load decreased gradually in both surface conditions of specimen. In all these repairsystems, a single kink-crack always leads to final failure, and the influence of surface preparation is not reflected in the experimental data. Instead, only the fracture behavior of the repair material (concrete versus SFRC) are revealed in the test data. These specimen failures are characterized bya single kinked crack with immediate softening following elastic response.。

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外文资料The Tenth East Asia-Pacific Conference on Structural Engineering and ConstructionAugust 3-5, 2006, Bangkok, ThailandStructural Rehabilitation of Concrete Bridges with CFRPComposites-Practical Details and ApplicationsRiyad S. ABOUTAHA1, and Nuttawat CHUTARAT2 ABSTRACT: Many old existing bridges are still active in the various highway transportation networks, carrying heavier and faster trucks, in all kinds of environments. Water, salt, and wind have caused damage to these old bridges, and scarcity of maintenance funds has aggravated their conditions. One attempt to restore the original condition; and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites. There appear to be very limited guides on repair of deteriorated concrete bridges with CFRP composites. In this paper, guidelines for nondestructive evaluation (NDE), nondestructive testing (NDT), and rehabilitation of deteriorated concrete bridges with CFRP composites are presented. The effect of detailing on ductility and behavior of CFRP strengthened concrete bridges are also discussed and presented.KEYWORDS: Concrete deterioration, corrosion of steel, bridge rehabilitation, CFRP composites.1 IntroductionThere are several destructive external environmental factors that limit the service life of bridges. These factors include but not limited to chemical attacks, corrosion of reinforcing steel bars, carbonation of concrete, and chemical reaction of aggregate. If bridges were not well maintained, these factors may lead to a structural deficiency, which reduces the margin of safety, and may result in structural failure. In order to rehabilitate and/or strengthen deteriorated existing bridges, thorough evaluation should be conducted. The purpose of the evaluation is to assess the actual condition of any existing bridge, and generally to examine the remaining strength and load carry capacity of the bridge.1 Associate Professor, Syracuse University, U.S.A.2 Lecturer, Sripatum University, Thailand.One attempt to restore the original condition, and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites.In North America, Europe and Japan, CFRP has been extensively investigated and applied. Several design guides have been developed for strengthening of concrete bridges with CFRP composites. However, there appear to be very limited guides on repair of deteriorated concrete bridges with CFRP composites. This paper presents guidelines for repair of deteriorated concrete bridges, along with proper detailing. Evaluation, nondestructive testing, and rehabilitation of deteriorated concrete bridges with CFRP composites are presented. Successful application of CFRP composites requires good detailing as the forces developed in the CFRP sheets are transferred by bond at the concrete-CFRP interface. The effect of detailing on ductility and behavior of CFRP strengthened concrete bridges will also be discussed and presented.2 Deteriorated Concrete BridgesDurability of bridges is of major concern. Increasing number of bridges are experiencing significant amounts of deterioration prior to reaching their design service life. This premature deterioration considered a problem in terms of the structural integrity and safety of the bridge. In addition, deterioration of a bridge has a considerable magnitude of costs associated with it. In many cases, the root of a deterioration problem is caused by corrosion of steel reinforcement in concrete structures. Concrete normally acts to provide a high degree of protection against corrosion of the embedded reinforcement. However, corrosion will result in those cases that typically experience poor concrete quality, inadequate design or construction, and harsh environmental conditions. If not treated a durability problem, e.g. corrosion, may turn into a strength problem leading to a structural deficiency, as shown in Figure1.Figure1 Corrosion of the steel bars is leading to a structural deficiency3 Non-destructive Testing of Deteriorated Concrete Bridge PiersIn order to design a successful retrofit system, the condition of the existing bridge should be thoroughly evaluated. Evaluation of existing bridge elements or systems involves review of the asbuilt drawings, as well as accurate estimate of the condition of the existing bridge, as shown in Figure2. Depending on the purpose of evaluation, non-destructive tests may involve estimation of strength, salt contents, corrosion rates, alkalinity in concrete, etc.Figure2 Visible concrete distress marked on an elevation of a concrete bridge pier Although most of the non-destructive tests do not cause any damage to existing bridges, some NDT may cause minor local damage (e.g. drilled holes & coring) that should be repaired right after the NDT. These tests are also referred to as partial destructive tests but fall under non-destructive testing.In order to select the most appropriate non-destructive test for a particular case, thepurpose of the test should be identified. In general, there are three types of NDT to investigate: (1) strength, (2) other structural properties, and (3) quality and durability. The strength methods may include; compressive test (e.g. core test/rebound hammer/ ultrasonic pulse velocity), surface hardness test (e.g. rebound hammer), penetration test (e.g. Windsor probe), and pullout test (anchor test).Other structural test methods may include; concrete cover thickness (cover-meter), locating rebars (rebar locator), rebar size (some rebar locators/rebar data scan), concrete moisture (acquameter/moisture meter), cracking (visual test/impact echo/ultrasonic pulse velocity), delamination (hammer test/ ultrasonic pulse velocity/impact echo), flaws and internal cracking (ultrasonic pulse velocity/impact echo), dynamic modulus of elasticity (ultrasonic pulse velocity), Possion’s ratio (ultrasonic pulse velocity), thickness of concrete slab or wall (ultrasonic pulse velocity), CFRP debonding (hammer test/infrared thermographic technique), and stain on concrete surface (visual inspection).Quality and durability test methods may include; rebar corrosion rate –field test, chloride profile field test, rebar corrosion analysis, rebar resistivity test, alkali-silica reactivity field test, concrete alkalinity test (carbonation field test), concrete permeability (field test for permeability).4 Non-destructive Evaluation of Deteriorated Concrete Bridge PiersThe process of evaluating the structural condition of an existing concrete bridge consists of collecting information, e.g. drawings and construction & inspection records, analyzing NDT data, and structural analysis of the bridge. The evaluation process can be summarized as follows: (1) Planning for the assessment, (2) Preliminary assessment, which involves examination of available documents, site inspection, materials assessment, and preliminary analysis, (3) Preliminary evaluation, this involves: examination phase, and judgmental phase, and finally (4) the cost-impact study.If the information is insufficient to conduct evaluation to a specific required level, then a detailed evaluation may be conducted following similar steps for the above-mentioned preliminary assessment, but in-depth assessment. Successful analytical evaluation of an existing deteriorated concrete bridge should consider the actual condition of the bridge and level of deterioration of various elements. Factors, e.g. actual concrete strength, level of damage/deterioration, actual size of corroded rebars, loss of bond between steel and concrete, etc. should be modeled into a detailed analysis. If such detailed analysis is difficult to accomplish within a reasonable period of time, thenevaluation by field load testing of the actual bridge in question may be required.5 Bridge Rehabilitation with CFRP CompositesApplication of CFRP composite materials is becoming increasingly attractive to extend the service life of existing concrete bridges. The technology of strengthening existing bridges with externally bonded CFRP composites was developed primarily in Japan (FRP sheets), and Europe (laminates). The use of these materials for strengthening existing concrete bridges started in the 1980s, first as a substitute to bonded steel plates, and then as a substitute for steel jackets for seismic retrofit of bridge columns. CFRP Composite materials are composed of fiber reinforcement bonded together with a resin matrix. The fibers provide the composite with its unique structural properties. The resin matrix supports the fibers, protect them, and transfer the applied load to the fibers through shearing stresses. Most of the commercially available CFRP systems in the construction market consist of uniaxial fibers embedded in a resin matrix, typically epoxy. Carbon fibers have limited ultimate strain, which may limit the deformability of strengthened members. However, under traffic loads, local debonding between FRP sheets and concrete substrate would allow for acceptable level of global deformations before failure.CFRP composites could be used to increase the flexural and shear strength of bridge girders including pier cap beams, as shown in Figure3. In order to increase the ductility of CFRP strengthened concrete girders, the longitudinal CFRP composite sheets used for flexural strengthening should be anchored with transverse/diagonal CFRP anchors to prevent premature delamination of the longitudinal sheets due to localized debonding at the concrete surface-CFRP sheet interface. In order to prevent stress concentration and premature fracture of the CFRP sheets at the corners of concrete members, the corners should be rounded at 50mm (2.0 inch) radius, as shown in Figure3.Deterioration of concrete bridge members due to corrosion of steel bars usually leads in loss of steel section and delamination of concrete cover. As a result, such deterioration may lead to structural deficiency that requires immediate attention. Figure4 shows rehabilitation of structurally deficient concrete bridge pier using CFRP composites.Figure3 Flexural and shear strengthening of concrete bridge pier with FRP compositesFigure4 Rehabilitation of deteriorated concrete bridge pier with CFRP composites6 Summary and ConclusionsEvaluation, non-destructive testing and rehabilitation of deteriorated concrete bridges were presented. Deterioration of concrete bridge components due to corrosion may lead to structural deficiencies, e.g. flexural and/or shear failures. Application of CFRP composite materials is becoming increasingly attractive solution to extend the service life of existing concrete bridges. CFRP composites could be utilized for flexural and shear strengthening, as well as for restoration of deteriorated concrete bridge components. The CFRP composite sheets should be well detailed to prevent stress concentration and premature fracture or delamination. For successful rehabilitation of concrete bridges in corrosive environments, a corrosion protection system should be used along with the CFRP system.第十届东亚太结构工程设计与施工会议2006年8月3-5号,曼谷,泰国碳纤维复合材料修复混凝土桥梁结构的详述及应用Riyad S. ABOUTAHA1, and Nuttawat CHUTARAT2摘要:在各式各样的公路交通网络中,许多现有的古老桥梁,在各种恶劣的环境下,如更重的荷载和更快的车辆等条件下,依然在被使用着。

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