毕业设计混凝土桥梁结构形式(中英文翻译)
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。
桥梁工程专业英语
有限元法
finite element method
有限元法: FInite Element|finite element method
积有限元法：CVFEM线性有限元法: Linear Finite Element Method
等效荷载原理：principle of equivalent loads
等效负载等效荷载等值负载: equivalentload
模型
matrixmodelmouldpattern
承载能力极限状态
承载能力极限状态: ultimate limit states
正常使用极限状态
serviceability limit state
安全系数
safety factor
标准值
standard value标准值：standard value,｜reference value
作用标准值: characteristic value of an action重力标准值：gravity standard
设计值
value of calculationdesign value
单墩
单墩: single pier单墩尾水管: single-pier draught tube
单墩肘形尾水管: one-pier elbow draught tube
结构优化设计
结构优化设计: optimal structure designing
扩结构优化设计：Optimal Struc ture Designing
液压机结构优化设计软件包: HYSOP
连续多跨
多跨连续梁: continuous beam on many supports
桥梁专业毕设文献翻译知识分享
毕业设计(文献翻译)译文及原文复印件学生姓名：左烨学号： 1804070233 所在学院：交通学院专业：交通工程文献题目： Bridges桥梁类型指导教师：罗韧南京工业大学土木工程学院交通工程系二O一一年三月桥梁类型梁桥梁桥也许是最普遍也是最基本的桥梁结构形式。
一根木头跨越小河是典型梁桥的一种最简单的实例。
在现代的钢梁桥结构形式中，最常见的两种型式是I 型梁桥和箱梁。
如果我们考察I型梁的横截面我们马上就能理解为什么它被冠以如此的名字（见插图1）。
梁的横断面采用了英文字母I大写的形状。
中间的垂直板被称为肋板，而顶部和底部的平面板指的就是凸缘。
要解释I型梁为什么是一种有效的截面型式是一项长期而艰巨的任务，因此在本篇文章中我们就不做解释了。
箱梁得名如同于I型梁一样，很明显，它的截面形状类似于一个箱子。
典型的箱梁截面型式有两个肋板和两个凸缘（见插图2）。
但是在某些情况下，两个以上的肋板就会形成存在剪力滞现象的多室箱梁。
其他梁桥的例子包括π型梁——因其截面类似于数学符号π而得名，还有T 型梁。
因为绝大部分现今建造的梁桥都属于箱梁或是I型梁，所以我们会跳过这些少见的截面类型。
现在我们了解了I型梁和箱梁之间的外形差异，让我们来看看这两种截面型式的优缺点。
I型梁截面设计和建造简单，在大部分情况下，使用效果也很好。
但是，如果梁桥有任何形式的弯曲，梁就会受扭，也就是众所周知的扭矩。
对比于I型梁，在箱梁中添加的第二个肋板增加了稳定性，也就增加了箱梁的抗扭性能。
这就使得箱梁截面成为存在显著曲线梁桥的理想选择。
箱梁结构更稳定可以跨越更长的距离且经常用于大跨径桥梁，而使用I型梁就不会有足够的强度和稳定性。
然而，设计构造箱梁桥相比于I型梁更为困难。
例如，为了焊接箱型梁内的接缝，人工或是机械就必须能够控制箱梁产生的剪力滞。
桁架桥桁架是一种简单的类似于骨骼的结构。
在结构力学中，简单桁架的单个组成部分只受到拉力和压缩力，而不存在弯曲力。
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。
毕业设计中英文翻译
Bridge Waterway OpeningsIn a majority of cases the height and length of a bridge depend solely upon the amount of clear waterway opening that must be provided to accommodate the floodwaters of the stream. Actually, the problem goes beyond that of merely accommodating the floodwaters and requires prediction of the various magnitudes of floods for given time intervals. It would be impossible to state that some given magnitude is the maximum that will ever occur, and it is therefore impossible to design for the maximum, since it cannot be ascertained. It seems more logical to design for a predicted flood of some selected interval ---a flood magnitude that could reasonably be expected to occur once within a given number of years. For example, a bridge may be designed for a 50-year flood interval; that is, for a flood which is expected (according to the laws of probability) to occur on the average of one time in 50 years. Once this design flood frequency, or interval of expected occurrence, has been decided, the analysis to determine a magnitude is made. Whenever possible, this analysis is based upon gauged stream records. In areas and for streams where flood frequency and magnitude records are not available, an analysis can still be made. With data from gauged streams in the vicinity, regional flood frequencies can be worked out; with a correlation between the computed discharge for the ungauged stream and the regional flood frequency, a flood frequency curve can be computed for the stream in question. Highway CulvertsAny closed conduit used to conduct surface runoff from one side of a roadway to the other is referred to as a culvert. Culverts vary in size from large multiple installations used in lieu of a bridge to small circular or elliptical pipe, and their design varies in significance. Accepted practice treats conduits under the roadway as culverts. Although the unit cost of culverts is much less than that of bridges, they are far more numerous, normally averaging about eight to the mile, and represent a greater cost in highway. Statistics show that about 15 cents of the highway construction dollar goes to culverts, as compared with 10 cents for bridge. Culvert design then is equally as important as that of bridges or other phases of highway and should be treated accordingly.Municipal Storm DrainageIn urban and suburban areas, runoff waters are handled through a system of drainage structures referred to as storm sewers and their appurtenances. The drainage problem is increased in these areas primarily for two reasons: the impervious nature of the area creates a very high runoff; and there is little room for natural water courses. It is often necessary to collect the entire storm water into a system of pipes and transmit it over considerable distances before it can be loosed again as surface runoff. This collection and transmission further increase the problem, since all of the water must be collected with virtually no ponding, thus eliminating any natural storage; and though increased velocity the peak runoffs are reached more quickly. Also, the shorter times of peaks cause the system to be more sensitive to short-duration, high-intensity rainfall. Storm sewers, like culverts and bridges, are designed for storms of various intensity –return-period relationship, depending upon the economy and amount of ponding that can be tolerated.Airport DrainageThe problem of providing proper drainage facilities for airports is similar in many ways to that of highways and streets. However, because of the large and relatively flat surface involved the varying soil conditions, the absence of natural water courses and possible side ditches, and the greater concentration of discharge at the terminus of the construction area, some phases of the problem are more complex. For the average airport the overall area to be drained is relatively large and an extensive drainage system is required. The magnitude of such a system makes it even more imperative that sound engineeringprinciples based on all of the best available data be used to ensure the most economical design. Overdesign of facilities results in excessive money investment with no return, and underdesign can result in conditions hazardous to the air traffic using the airport.In other to ensure surfaces that are smooth, firm, stable, and reasonably free from flooding, it is necessary to provide a system which will do several things. It must collect and remove the surface water from the airport surface; intercept and remove surface water flowing toward the airport from adjacent areas; collect and remove any excessive subsurface water beneath the surface of the airport facilities and in many cases lower the ground-water table; and provide protection against erosion of the sloping areas. Ditches and Cut-slope DrainageA highway cross section normally includes one and often two ditches paralleling the roadway. Generally referred to as side ditches these serve to intercept the drainage from slopes and to conduct it to where it can be carried under the roadway or away from the highway section, depending upon the natural drainage. To a limited extent they also serve to conduct subsurface drainage from beneath the roadway to points where it can be carried away from the highway section.A second type of ditch, generally referred to as a crown ditch, is often used for the erosion protection of cut slopes. This ditch along the top of the cut slope serves to intercept surface runoff from the slopes above and conduct it to natural water courses on milder slopes, thus preventing the erosion that would be caused by permitting the runoff to spill down the cut faces.12 Construction techniquesThe decision of how a bridge should be built depends mainly on local conditions. These include cost of materials, available equipment, allowable construction time and environmental restriction. Since all these vary with location and time, the best construction technique for a given structure may also vary. Incremental launching or Push-out MethodIn this form of construction the deck is pushed across the span with hydraulic rams or winches. Decks of prestressed post-tensioned precast segments, steel or girders have been erected. Usually spans are limited to 50～60 m to avoid excessive deflection and cantilever stresses , although greater distances have been bridged by installing temporary support towers . Typically the method is most appropriate for long, multi-span bridges in the range 300 ~ 600 m ,but ,much shorter and longer bridges have been constructed . Unfortunately, this very economical mode of construction can only be applied when both the horizontal and vertical alignments of the deck are perfectly straight, or alternatively of constant radius. Where pushing involves a small downward grade (4% ~ 5%) then a braking system should be installed to prevent the deck slipping away uncontrolled and heavy bracing is then needed at the restraining piers.Bridge launching demands very careful surveying and setting out with continuous and precise checks made of deck deflections. A light aluminum or steel-launching nose forms the head of the deck to provide guidance over the pier. Special teflon or chrome-nickel steel plate bearings are used to reduce sliding friction to about 5% of the weight, thus slender piers would normally be supplemented with braced columns to avoid cracking and other damage. These columns would generally also support the temporary friction bearings and help steer the nose.In the case of precast construction, ideally segments should be cast on beds near the abutments and transferred by rail to the post-tensioning bed, the actual transport distance obviously being kept to the minimum. Usually a segment is cast against the face of the previously concerted unit to ensure a good fit when finally glued in place with an epoxy resin. If this procedure is not adopted , gaps of approximately 500mm shold be left between segments with the reinforcements running through andstressed together to form a complete unit , but when access or space on the embankment is at a premium it may be necessary to launch the deck intermittently to allow sections to be added progressively .The correponding prestressing arrangements , both for the temporary and permanent conditions would be more complicated and careful calculations needed at all positions .The pricipal advantage of the bridge-launching technique is the saving in falsework, especially for high decks. Segments can also be fabricated or precast in a protected environment using highly productive equipment. For concrete segment, typically two segment are laid each week (usually 10 ~ 30 m in length and perhaps 300 to 400 tonnes in weight) and after posttensioning incrementally launched at about 20 m per day depending upon the winching/jacking equipment.Balanced Cantiulever ConstructionDevelopment in box section and prestressed concrete led to short segment being assembled or cast in place on falsework to form a beam of full roadway width. Subsequently the method was refined virtually to eliminate the falsework by using a previously constructed section of the beam to provide the fixing for a subsequently cantilevered section. The principle is demonsrated step-by-step in the example shown in Fig.1.In the simple case illustrated, the bridge consists of three spans in the ratio 1:1:2. First the abutments and piers are constructed independently from the bridge superstructure. The segment immediately above each pier is then either cast in situ or placed as a precast unit .The deck is subsequently formed by adding sections symmetrically either side.Ideally sections either side should be placed simultaneously but this is usually impracticable and some inbalance will result from the extra segment weight, wind forces, construction plant and material. When the cantilever has reached both the abutment and centre span,work can begin from the other pier , and the remainder of the deck completed in a similar manner . Finally the two individual cantilevers are linked at the centre by a key segment to form a single span. The key is normally cast in situ.The procedure initially requires the first sections above the column and perhaps one or two each side to be erected conventionally either in situ concrete or precast and temporarily supported while steel tendons are threaded and post-tensioned . Subsequent pairs of section are added and held in place by post-tensioning followed by grouting of the ducts. During this phase only the cantilever tendons in the upper flange and webs are tensioned. Continuity tendons are stressed after the key section has been cast in place. The final gap left between the two half spans should be wide enough to enable the jacking equipment to be inserted. When the individual cantilevers are completed and the key section inserted the continuity tendons are anchored symmetrically about the centre of the span and serve to resist superimposed loads, live loads, redistribution of dead loads and cantilever prestressing forces.The earlier bridges were designed on the free cantilever principle with an expansion joint incorporated at the center .Unfortunately，settlements , deformations , concrete creep and prestress relaxation tended to produce deflection in each half span , disfiguring the general appearance of the bridge and causing discomfort to drivers .These effects coupled with the difficulties in designing a suitable joint led designers to choose a continuous connection, resulting in a more uniform distribution of the loads and reduced deflection. The natural movements were provided for at the bridge abutments using sliding bearings or in the case of long multi-span bridges, joints at about 500 m centres.Special Requirements in Advanced Construction TechniquesThere are three important areas that the engineering and construction team has to consider:(1) Stress analysis during construction: Because the loadings and support conditions of the bridge are different from the finished bridge, stresses in each construction stage must be calculated to ensurethe safety of the structure .For this purpose, realistic construction loads must be used and site personnel must be informed on all the loading limitations. Wind and temperature are usually significant for construction stage.(2) Camber: In order to obtain a bridge with the right elevation, the required camber of the bridge at each construction stage must be calculated. It is required that due consideration be given to creep and shrinkage of the concrete. This kind of the concrete. This kind of calculation, although cumbersome, has been simplified by the use of the compiters.(3) Quality control: This is important for any method construction, but it is more so for the complicated construction techniques. Curing of concrete, post-tensioning, joint preparation, etc. are detrimental to a successful structure. The site personnel must be made aware of the minimum concrete strengths required for post-tensioning, form removal, falsework removal, launching and other steps of operations.Generally speaking, these advanced construction techniques require more engineering work than the conventional falsework type construction, but the saving could be significant.大桥涵洞在大多数情况中桥梁的高度和跨度完全取决于河流的流量，桥梁的高度和跨度必须能够容纳最大洪水量.事实上，这不仅仅是洪水最大流量的问题,还需要在不同时间间隔预测不同程度的水灾。
桥梁工程毕业设计外文翻译(箱梁)
西南交通大学本科毕业设计(论文）外文资料翻译年级:学号：姓名：专业:指导老师:2013年 6 月外文资料原文：13Box girders13.1 GeneralThe box girder is the most flexible bridge deck form。
It can cover a range of spans from25 m up to the largest non—suspended concrete decks built, of the order of 300 m。
Single box girders may also carry decks up to 30 m wide。
For the longer span beams, beyond about 50 m，they are practically the only feasible deck section. For the shorter spans they are in competition with most of the other deck types discussed in this book.The advantages of the box form are principally its high structural efficiency （5.4），which minimises the prestress force required to resist a given bending moment，and its great torsional strength with the capacity this gives to re—centre eccentric live loads，minimising the prestress required to carry them。
The box form lends itself to many of the highly productive methods of bridge construction that have been progressively refined over the last 50 years，such as precast segmental construction with or without epoxy resin in the joints，balanced cantilever erection either cast in—situ or coupled with precast segmental construction, and incremental launching （Chapter 15)。
(完整版)桥梁毕业设计外文翻译
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。
混凝土结构 中英文 PPT 演示文稿
几个小伙伴为您讲课啦！！！165•Plain concrete is formed from a hardened mixture of cement ,water ,fine aggregate, coarse aggregate (crushed stone or gravel),air, and often other admixtures. The plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction lf thecement/water mix, resulting in hardened concrete.•素混凝土是由水泥、水、细骨料、粗骨料（碎石或卵石）、空气，通常还有其他外加剂等经过凝固硬化而成。
将可塑的混凝土拌合物注入到模板内，并将其捣实，然后进行养护，以加速水泥与水的水化反应，最后获得硬化的混凝土。
•The finished product has high compressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth lf its compressive strength. Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to compensate for the weak tension regions in the reinforced concrete element.•其最终制成品具有较高的抗压强度和较低的抗拉强度。
建筑专业土木工程词汇及术语中英文对照.
建筑专业笔记整理大全-结构工程常用词汇-土木工程常用英语术语结构工程常用词汇混凝土：concrete钢筋：reinforcing steel bar钢筋混凝土：reinforced concrete（RC）钢筋混凝土结构：reinforced concrete structure板式楼梯：cranked slab stairs刚度：rigidity徐变：creep水泥：cement钢筋保护层：cover to reinforcement梁：beam柱：column板：slab剪力墙：shear wall基础：foundation剪力：shear剪切变形：shear deformation剪切模量：shear modulus拉力：tension压力：pressure延伸率：percentage of elongation位移：displacement应力：stress应变：strain应力集中：concentration of stresses应力松弛：stress relaxation应力图：stress diagram应力应变曲线：stress-strain curve应力状态：state of stress钢丝：steel wire箍筋：hoop reinforcement箍筋间距：stirrup spacing加载：loading抗压强度：compressive strength抗弯强度：bending strength抗扭强度：torsional strength抗拉强度：tensile strength裂缝：crack屈服：yield屈服点：yield point屈服荷载：yield load屈服极限：limit of yielding屈服强度：yield strength屈服强度下限：lower limit of yield荷载：load横截面：cross section承载力：bearing capacity承重结构：bearing structure弹性模量：elastic modulus预应力钢筋混凝土：prestressed reinforced concrete预应力钢筋：prestressed reinforcement预应力损失：loss of prestress预制板：precast slab现浇钢筋混凝土结构：cast-in-place reinforced concrete 双向配筋：two-way reinforcement主梁：main beam次梁：secondary beam弯矩：moment悬臂梁：cantilever beam延性：ductileity受弯构件：member in bending受拉区：tensile region受压区：compressive region塑性：plasticity轴向压力：axial pressure轴向拉力：axial tension吊车梁：crane beam可靠性：reliability粘结力：cohesive force外力：external force弯起钢筋：bent-up bar弯曲破坏：bending failure屋架：roof truss素混凝土：non-reinforced concrete无梁楼盖：flat slab配筋率：reinforcement ratio配箍率：stirrup ratio泊松比：Poisson’s ratio偏心受拉：eccentric tension偏心受压：eccentric compression偏心距：eccentric distance疲劳强度：fatigue strength偏心荷载：eccentric load跨度：span跨高比：span-to-depth ratio跨中荷载：midspan load框架结构：frame structure集中荷载：concentrated load分布荷载：distribution load分布钢筋：distribution steel挠度：deflection设计荷载：design load设计强度：design strength构造：construction简支梁：simple beam截面面积：area of section浇注：pouring浇注混凝土：concreting钢筋搭接：bar splicing刚架：rigid frame脆性：brittleness脆性破坏：brittle failure土木工程常用英语术语第一节一般术语1. 工程结构building and civil engineering structures房屋建筑和土木工程的建筑物、构筑物及其相关组成部分的总称。
桥梁名词中英文对照(修改版)
A类部分预应力混凝土type A partially prestressed concreteA形索塔A-framed towerB类部分预应力混凝土type B partially prestressed concreteGM法Guyon-Massonet methodJM12型锚具J M 12 anchorageOVM锚具oriental cone anchorage;T[形]梁桥T-beam bridgeT形刚构桥T-shaped rigid frame bridgeT形梁T[-shaped] beamT形桥台T-abutmentU形梁U[-shaped] beamU形桥台U-abutmentVSL锚具VSL anchorage; 瑞士VSL 厂生产的国际通用夹片锚具。
W型护栏w-type guardrailXM锚具X-typed anchorage; X型三夹片式群锚。
YM锚具Y-typed anchorage, post-tensioning strand group anchorage;[桥]台后回填back filling behind abutment[桥基]沉降settlement[桥梁]动力回应试验bridge response to forced vibration[桥头]锥坡conical slope八字形桥台flare wing-walled abutment板slab板端错台faulting of slab ends板肋拱桥slab-rib arch bridge板桥slab bridge板式橡胶支座laminated rubber bearing板体断裂slab rupture板体翘曲slab warping板体温度翘曲应力slab stress due to thermal warping板桩sheet pile板桩围堰sheet pile cofferdam便桥detour bridge标准车辆荷载standard truck loading波纹钢桥面corrugated steel deck波纹管涵corrugated-metal pipe culvert波形梁护栏corrugated beam barrier超载预压surcharge preloading车道lane车道分布lane distribution车道荷载lane load车间净距vehicular gap沉管灌注桩tube-sinking cast-in-situ pile沉降差differential settlement沉井基础open caisson foundation沉井刃脚caisson cutting edge冲击系数impact factor;承台bearing platform, pile cap冲刷scouring erosion搭接钢板接缝lapped steel plate joint打入桩driven pile打桩pile driving搭接钢板接缝lapped steel plate joint打入桩driven pile打桩pile driving大跨径桥long span bridge单铰拱桥single-hinged arch bridge单室箱梁single cell box girder单索面斜拉桥single plane cable stayed bridge单向板one-way slab单向推力墩single direction thrusted pier单柱式[桥]墩single-columned pier, single shaft pier 单桩individual pile, single pile单桩承载力bearing capacity of pile弹性梁支承法elastic supported beam method弹性模量modulus of elasticity挡土墙retaining wall地震荷载earthquake load seismic force; 又称“地震力”。
土木工程毕业设计外文翻译(桥梁方面)
钢筋混凝土拱桥的施工控制钢筋混凝土拱桥是跨越河谷或深谷理想的拱桥。
然而，拱肋的施工往往是非常最重要的方面，可能会影响桥梁的可行性。
现场浇注混凝土的模板和脚手架上直接支持的山谷往往是出了问题。
近年来逐渐流行的一种方法是使用预制混凝土管片竖立悬臂施工方法与回接。
由于回接是暂时的，因此可收回的，该方法被认为是非常经济的。
本文介绍了一种施工控制方法。
它使用在调整索力的影响系数矩阵的概念中的应力保持在可接受的范围内，以及拱肋，以确保拱肋构造线和水平。
它是观察到所要求的最低回接力变化在悬臂施工进度。
的张紧回接的各种不同的策略进行了研究，并且发现，一个两阶段的的张紧方法给出可接受的结果。
最近的应用所提出的方法和结果也有所说明。
CE数据库关键词：桥梁，拱，施工管理，混凝土，钢筋介绍在中国的西南部分广阔的山区，大部分的溪流和河流是陡坡，且水流快。
基岩主要是石灰石和覆盖在山谷非常甚至不存在的薄粘质土壤。
拱桥因此非常适合在这种情况下，的确有大量在该地区已建成的拱桥。
自从1400岁的赵周桥修建后，见证了桥的拱形式一直是自古以来最流行的桥梁方式。
拱桥往往被视为审美形式的桥梁。
林顿（1977），本伯格（1084）等人的拱形桥的历史和发展的各个方面进行了讨论。
然而，拱肋的施工往往是非常最重要的方面，可能会影响桥梁的可行性。
为了克服勃起问题，可以构建现代拱桥钢筋混凝土（伯格等1984a，b；赫德1997），钢（克努森1997）或复合技术，采用钢桁梁悬臂和大梁（池田等1992），或钢管（奥胡拉和加藤1993）。
然而，在中国这样一个发展中国家，钢筋混凝土仍然是相对更经济。
对于一个深谷的情况下，现场浇注混凝土的模板和脚手架上直接支持的山谷往往是出了问题。
近年来逐渐流行的一种方法是使用预制混凝土管片，并竖立他们从每个桥墩悬臂施工方法与回接。
技术已在斜拉桥以及一些拱桥的建设取得成功尝试。
由于回接是暂时的，因此可收回的，该方法被认为是非常经济的。
道路桥梁毕业设计翻译-英文
Computers and Structures 74 (2000) 1±9/locate/compstruc Determination of initial cable forces in prestressed concrete cable-stayed bridges for given design deck pro®les usingthe force equilibrium methodD.W. Chen a, F.T.K. Au b,*, L.G. Tham b, P.K.K. Lee baDepartment of Bridge Engineering, Tongji University, Shanghai, People's Republic of ChinabDepartment of Civil Engineering, The University of Hong Kong, Hong Kong, People's Republic of ChinaReceived 14 August 1997; accepted 18 November 1998AbstractThe determination of initial cable forces in a prestressed concrete cable-stayed bridge for a given vertical pro®le of deck under its dead load is an important but di•cult task that a ects the overall design of the bridge. A new method utilizing the idea of force equilibrium is presented in this paper for their determination. The method can easily account for the e ect of prestressing and the additional bending moments due to the vertical pro®le of the bridge deck. It is much more rational and simple than the traditional ``zero displacement'' method, and it is able to achieve bending moments in the bridge deck approaching those in a continuous beam over rigid simple supports. # 1999 Elsevier Science Ltd. All rights reserved.Keywords: Prestressed concrete; Cable-stayed bridge; Initial cable force; Vertical pro®le1. IntroductionThe cable-stayed bridge is a modern form of bridge which is both economical and aesthetic. It has been extensively employed in the construction of long-span bridges in the past few decades. However this kind of structure is highly statically indetermi-nate, and therefore many schemes of initial cable forces are possible. In the particular case of pre-stressed concrete cable-stayed bridges, it is especially important to choose an appropriate scheme of initial cable forces while the bridge is under dead load only. Owing to shrinkage and creep, the de¯ections * Corresponding author. Tel.: +852-2859-2668; fax: +852-2559-5337. will change with the passage of time and the internal forces may also redistribute. Should an inappropriate scheme of initial cable forces be chosen, an un-favourable pattern of internal forces may be locked in subsequently, for which there may be no simple solution.Theoretically it is possible to search for a ``stable'' scheme of initial cable forces under which there is the minimum redistribution of internal forces and time-dependent displacements. However it is usually very di•cult in view of the many factors a ecting the sub-sequent time-dependent deformations. For example, many cable-stayed bridges are constructed using cast in situ segmental cantilever construction, which gives rise to complex e ects of shrinkage and creep because of the di erent ages of concrete. The presence of longi-tudinal prestressing also complicates the problem0045-7949/00/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S 0 0 4 5 - 7 9 4 9 ( 9 8 ) 0 0 3 1 5 - 02 D.W. Chen et al. / Computers and Structures 74 (2000) 1±9further. Inevitably some simplifying assumptions have to be made.2. Review of existing methodsThe scheme of initial cable forces giving rise to bending moments in the bridge deck approaching those of an equivalent continuous beam with all the supports from cables and towers considered as rigid simple supports is generally acknowledged to be both rational and practi-cal, as the long-term behaviour of the bridge is reason-ably ``stable''. The problem hinges upon how to achieve this scheme of initial cable forces. There are two main categories of methods in achieving an appropriate scheme of initial cable forces in prestressed concrete cable-stayed bridges [1±8], namely the optimization method [2±5] and the ``zero displacement'' method [6].In the optimization method [2±5], the initial cable forces are chosen based on the optimization of certain objective functions which may either be related to structural e•ciency or economy. In this method, the total strain energy is often one of the objective func-tions to be minimized. It is necessary to impose the constraints for optimization very carefully, or else the resulting schemes may sometimes become impractical.On the other hand, the traditional ``zero displace-ment'' method [6] is more straightforward in theory, and it enables the designer to ®ne-tune the initial cable forces as well as the structural con®guration. If a straight and horizontal bridge deck is supported on a number of stay cables, the horizontal components of the cable forces have little e ect on the bending moments of the deck, and hence the bending moments are primarily governed by the vertical components of the cable forces and the dead load. In the ``zero displa-cement'' method, an appropriate scheme of initial cable forces is obtained by making the de¯ections at the cable anchorages vanish. When the deck gradient is negligible, the resulting bending moments in the deck are essentially those of an equivalent continuous beam with all supports from cables and towers con-sidered as rigid simple supports. However, when the vertical pro®le of the bridge deck is signi®cant by reason of tra•c requirements or otherwise, the basis of this method is itself questionable. As the horizontal components of the cable forces will induce additional bending moments in the deck, the resulting bending moments are likely to cause substantial redistribution in the long run. In this case, what really matter are the bending moments because they will a ect the long term behaviour of the bridge. Whether the correspond-ing displacements are zero or not is immaterial, as they can be adequately controlled by appropriate precamber or preset of the deck during construction.In this paper, a new method utilizing the idea of force equilibrium is presented for the determination of a ``stable'' scheme of initial cable forces. The method can easily account for the e ect of prestressing and the vertical pro®le of the bridge deck, and therefore it is much more rational as well as simpler than the tra-ditional ``zero displacement'' method. Two numerical examples using real cases of prestressed concrete cable-stayed bridges are presented to demonstrate the versa-tility of the proposed method.3. The force equilibrium methodIn the force equilibrium method, the cable-stayed bridge is modelled as a planar structure. The method works on an evolving substructure eventually compris-ing the bridge deck and towers, and searches for a set of cable forces which will give rise to desirable bending moments at selected locations of the substructure. As the method works only on the equilibrium of forces rather than deformation, there is no need to deal with non-linearity caused by cable sag and other e ects. The method is therefore computationally e•cient.First of all, certain sections of the bridge deck andFig. 1. A typical single tower cable-stayed bridge.D.W. Chen et al. / Computers and Structures 74 (2000) 1±9 3Fig. 2. Stage 1 model for cable-stayed bridge shown in Fig. 1.tower are chosen as control sections where the bendingmoments are adjusted by varying the cable forces. Consider a typical single tower cable-stayed bridge, as shown in Fig. 1, in which the connection between the bridge deck and tower is monolithic. To establish the tar-get bending moments, only the bridge deck is considered. All supports from the cables and tower are replaced by rigid simple supports, as shown in Fig. 2. This is regarded as the Stage 1 model for the sake of subsequent discus-sions. The prestressing to be applied during construction is also taken into account. The bending moments caused by dead load in the bridge deck under such modi®ed sup-port conditions are then taken to be the target bending moments. It is noted that the prestressing to be intro-duced after the completion of the bridge deck is not taken into account here. These target bending moments are adopted because the e ects of creep and shrinkage of concrete tend to change the bending moments towards these target values in the long term anyway [1]. If the in-itial bending moments in the towers can be controlled at the same time, the scheme of initial cable forces is reason-ably stable. It is further assumed here that factors such as the di erences in age among deck segments are insigni®-cant in the long term and therefore they are neglected.Fig. 3 shows the same bridge as in Fig. 1, except that all cables are taken away and replaced by the in-ternal forces. This simpli®ed model applies to both Stages 2 and 3. The only di erence between these two stages lies in the degree of sophistication. The cable forces are taken as independent variables for adjust-ment of bending moments at the control sections. Normally the bending moment at each deck section where a cable is anchored is treated as a control par-ameter. It should be pointed out that wherever a model consists of a back-stay anchored at the deckabove an end pier, where the deck carries no bending moment, the corresponding cable force can be treated as an additional variable to improve the structural e•-ciency further. For example, the bending moment at the deck-tower junction or that at the tower base may be taken to be an additional control parameter as they are critical sections a ecting the long term behaviour. The target bending moments at the deck sections are those obtained from the Stage 1 model whereas the target bending moment at the chosen tower section is normally set as zero.The above arguments can also be extended to other con®gurations of cable-stayed bridges. In a symmetric single tower cable-stayed bridge without back-stays anchored above end piers, the bending moments in the tower should normally be zero under dead load, and therefore there is no need to treat any of these as a con-trol parameter. In a two-tower cable-stayed bridge of symmetric arrangement, it is only necessary to consider one half of the bridge with appropriate boundary con-ditions at the middle section to account for symmetry, and the above reasoning can similarly be applied.The main purpose for setting up the Stage 2 model is to evaluate the approximate in¯uence coe•cients, which are the bending moments at the control sections caused by a unit load in a certain cable. In order not to introduce the non-linearity of cable sti nesses, some simplifying assumptions are made. The self-weight of each cable is neglected, and hence the forces at the ends are roughly equal. The bending moments in the deck are primarily determined by the cable forces act-ing on the deck, and to a lesser degree by the cable forces acting on the tower. Therefore the cable forces acting on the tower are neglected in the calculation of bending moments in the deck. Similarly in the calcu-Fig. 3. Model for stages 2 and 3 for cable-stayed bridge shown in Fig. 1.4D.W. Chen et al. / Computers and Structures 74 (2000) 1±9lation of bending moment at the control section at the tower, only the cable forces acting on the tower are taken into account. The errors introduced by these simplifying assumptions will be almost eliminated by iterations in the next stage.Considering the equilibrium of the Stage 2 model, the following equation can be written:fM 0g ˆ ‰m Šf T g ‡ f M dg…1†where {M 0} is an N-dimensional vector containing thetarget bending moments M 0i derived from the Stage 1 model, [m ] is an N N matrix containing approximate in¯uence coe•cients m ij for the Stage 2 model in which m ij is the bending moment at the ith control sec-tion caused by a unit force in the jth cable, {T } is an N-dimensional vector containing the cable forcesT j , {M d} is an N-dimensional vector containing thebend-ing moments M di caused by only dead load and pres-tress in the Stage 2 model, N is the number of cables considered in the model, i is the subscript correspond-ing to the ith control section and j is the subscript cor-responding to the jth cable. If {M 0} contains the bending moments of the equiv-alent continuous beam on rigid simple supports as obtained from the Stage 1 model, and the control sec-tions are well chosen so that the matrix [m ] is non-singular, an initial estimate of the cable forces {T 0} can be calculated from the Stage 2 model asfT 0g ˆ ‰m Šÿ1ÿfM 0g ÿ f M dg {T 0…2† However the cable forces } obtained above are only rough estimates as the Stage 2 model does not take into account the interaction among tower, cables and deck. It is therefore necessary to build the Stage 3 model.In the Stage 3 model, the interaction among tower, cables and deck is taken into account by iterations. The cable forces at the deck anchorages are taken as independent variables in the optimization process, and the self-weight of each cable can also be introduced.Using the initial estimate of the cable forces {T 0}, as wellas the bending moments {M d} caused by dead load and prestress in the Stage 2 model, the updated deckbending moments {M 1} can be calculated from the Stage 3 model. Such bending moments are nor-mally dierent from the target bending moments {M 0}, and henceit is necessary to introduce some adjustments {DT 1} of the cable forces given byfDT 1g ˆ ‰m Šÿ1ÿfM 1g ÿ f M 0g 1…3†Using the updated cable forces {T } given by fT 1g ˆ f T 0g ‡ f DT 1g…4†the updated deck bending moments {M 2} can then be calculated again from the Stage 3 model. Notice that the approximate in¯uence matrix [m ] for the Stage 2 model has been used in the Stage 3 model, and hence further iterations are necessary. Furtheradjustments {DT 2} may be obtained byfDT 2g ˆ ‰m Šÿ1ÿfM 2g ÿ f M 0g…5†resulting in more accurate cable forces {T 2} given byFig. 4. Flow chart describing the present method.D.W. Chen et al. / Computers and Structures 74 (2000) 1±9 5fT 2g ˆ f Tg ‡ f DT1g ‡ f DT2g…6†This process can be repeated until the updated deck bending moments {M n} converge to {M 0}. This is summarized in the ¯ow chart shown in Fig. 4.4. Numerical examplesTwo numerical examples are presented to demon-strate that the present method is both rational and re-liable. Both are taken from existing prestressed concrete cable-stayed bridges in China, but some minor simplifying modi®cations are made.4.1. Example 1. A single tower prestressed concretecable-stayed bridge with harp arrangementThe ®rst example is a single tower prestressed con-crete cable-stayed bridge, situated in Ningbo City, China,with spans of 90 and 105 m. The moment of inertia (I D), the cross sectional area (A D) and the Young's modulus (E D) of the deck are 4.706 m4, 12.145 m2and 3.5 107 kN/m2, respectively. The stay cables are of the harp arrangement. Three types of stay cables are used, andtheir respective cross sec-tional areas (A S) are 0.013, 0.0166 and 0.0208 m2. The Young's modulus of the stay cables (E S) is 2.1 108 kN/m2. The tower is stepped with the biggest section below the bridge deck and the smallest section over the length where the cables areanchored. The moments of inertia (I T) of the tower are 11.212, 19.939 and 79.688 m4. The corresponding cross sectional areas (A T) are 14.46, 19.0 and 45 m2, respectively, while the Young's modulus (E T) is 3 107 kN/m2. The infor-mation on the prestressing is omitted for brevity.Three di erent vertical pro®les of the bridge deck have been considered. The bridge deck is straight and horizontal in case 1. In cases 2 and 3, both the vertical pro®les consist of a symmetric parabolic summit curve of 180 m horizontal length and a straight tangent of 15 m. The highest point is precisely at the tower lo-cation. The gradients of the straight tangents for cases 2 and 3 are 3% and 9%, respectively. Fig. 5 shows an elevation of the bridge for case 3.The present method was applied to optimize the bending moments in the bridge deck for the three cases, and the tolerance value used to terminate iter-ations was 5 kNm. The results for case 3 are shown graphically in Figs. 6±8. Notice that the deck bending moments after optimization agree well with the target values obtained from an equivalent beam on rigid simple supports, except at the tower section which was not chosen as a control section. The abrupt jumps in bending moment are caused by prestressing. The bend-ing moment at the tower base is also very close to zero after optimization.The three cases were also analysed by the ``zero dis-placement'' method using 0.001 m as the tolerance value to terminate iterations. The initial cable forces for the three cases obtained by the present method are tabulated in Table 1 and compared to those obtained by the ``zero displacement'' method. It is observed that when the bridge deck has no slope, i.e. case 1, results from the above two methods are e ectively the same. There are, however, marked di erences in the other two cases, especially in the cables close to the tower.4.2. Example 2. A single tower prestressed concretecable-stayed bridge with semi-fan arrangementThe second example is also a single tower pre-stressed concrete cable-stayed bridge, situated in Jilin Province, China, with spans of 95 and 132 m. The moment of inertia (I D), the cross sectional area (A D) and the Young's modulus (E D) of the deck are 5.1 m4, 10.579 m2 and 3.5 107 kN/m2, respectively. The stay cables are of the semi-fan arrangement. Three types ofFig. 5. A single tower prestressed concrete cable-stayed bridge with harp arrangement (example 1).6D.W. Chen et al. / Computers and Structures 74 (2000) 1±9Fig. 6. Internal forces in bridge deck of example 1 (case 3). (a) Target bending moment in kNm; (b) bending moment in kNm; (c) shear force in kN; (d) axial force in kN.stay cables are used, and their respective cross sec-tional areas (A S ) are 0.020, 0.019 and 0.013 m 2. TheYoung's modulus of the stay cables (E S ) is 2.1 108kN/m 2. The tower is stepped in a manner similar to example 1, and the moments of inertia (I T ) are 17.92,24.01 and 47.73 m 4. The corresponding cross sectionalareas (A T ) are 17.92, 13.44 and 37.20 m 2, respectively,while the Young's modulus (E T ) is 3 107 kN/m 2. The e ects of prestressing are not considered in this example for simplicity. The vertical pro®le consists of a symmetric parabolic summit curve of 190 m horizon-tal length and a straight tangent of 37 m. The highestpoint is again precisely at the tower location. The gra-dient of the straight tangent is 6% as shown in Fig. 9. The results obtained using the present method are shown in Figs. 10±12, indicating very good agreement between the deck bending moments and the target values.5. ConclusionsA new method utilizing the idea of force equilibrium is presented for the determination of an optimumFig. 7. Cable forces of example 1 (case 3) in kN.D.W. Chen et al. / Computers and Structures 74 (2000) 1±9 7 Fig. 8. Internal forces in bridge tower of example 1 (case 3). (a) Bending moment in kNm; (b) shear force in kN; (c) axial force in kN.scheme of initial cable forces in a prestressed concrete cable-stayed bridge for a given vertical pro®le of deck under its dead load as well as prestress. In the pro-posed method, the sti nesses of the cables do not enter into the calculations, and it therefore obviates the need Table 1Initial cable forces for example 1 (kN) for introducing non-linearity into the algorithm. The bending moments, rather than the displacements, of the deck are taken as parameters to be controlled. The additional bending moments caused by the vertical pro®le of the deck can also be taken into account.Case 1 Case 2 Case 3 Present Zero displacement Present Zero displacement Present Zero displacement Cable no. method method method method method method1 14,045 14,045 14,483 14,398 15,458 15,3512 3931 3931 3969 3975 4044 40653 8832 8832 8919 8915 9130 91164 6757 6757 6798 6800 6836 68415 7242 7242 7200 7200 7126 71256 6900 6900 6825 6818 6637 66307 7727 7727 7561 7590 7283 73118 6676 6676 6605 6497 6224 61179 6707 6707 6016 6416 5428 582610 2889 2889 4251 2754 3971 248411 14,618 14,618 11,288 14,323 11,143 13,75812 14,619 14,619 11,298 14,339 11,118 13,76913 2887 2888 4245 2747 3961 247414 6706 6706 6013 6414 5422 582015 6680 6680 6607 6499 6222 611516 7714 7714 7552 7582 7270 729917 6948 6948 6867 6860 6678 667118 7064 7064 7024 7025 6931 693419 7304 7304 7340 7339 7427 742120 6998 6998 7027 7032 7028 704421 10,768 10,768 10,922 10,912 11,560 11,52422 8924 8924 9306 9311 9908 99248 D.W. Chen et al. / Computers and Structures 74 (2000) 1±9Fig. 9. A single tower prestressed concrete cable-stayed bridge with semi-fan arrangement (example 2).Fig. 10. Internal forces in bridge deck of example 2. (a) Target bending moment in kNm; (b) bending moment in kNm; (c) shear force in kN; (d) axial force in kN.Fig. 11. Cable forces of example 2 in kN.D.W. Chen et al. / Computers and Structures 74 (2000) 1±9 9Fig. 12. Internal forces in bridge tower of example 2. (a) Bending moment in kNm; (b) shear force in kN; (c) axial force in kN.Two real prestressed concrete cable-stayed bridges have been investigated using the proposed method, which demonstrate that it is both rational and practi-cal.It is also observed that, as far as the initial bending moments of the tower are concerned, the harp arrange-ment is less favourable than the fan or semi-fan arrangement, as the cables are anchored over a larger length in the former case. The proposed method is also a handy tool for optimizing the bending moments in the tower. AcknowledgementsThe ®nancial support of the block grant from the University Research Committee, The University of Hong Kong is acknowledged.References[1] Analysis of secondary stresses in prestressed concretecable-stayed bridges due to creep. Shanghai Institute of Design and Research in Municipal Engineering, Shanghai, 1983 (in Chinese).[2] Furukawa K, Sugimoto H, Egusa T, Inoue K, Yamada Y.Studies on optimization of cable prestressing for cable-stayed bridges. In: Proceedings of International Conference on Cable-stayed Bridges, Bangkok, 1987. p.723±34.[3] Lu Q, Xu YG. Optimum tensioning of cable-stays.Chinese Journal of Highway and Transport 1990;3(1):38± 48 (in Chinese).[4] SimoÄes LMC, NegraÄo JHO. Optimization of cable-stayed bridges with box-girder decks. In: Proceedings of the 1997 5th International Conference on Computer Aided Optimum Design of Structures, Rome, Italy, 1997.p. 21± 32.[5] NegraÄo JHO, SimoÄes LMC. Optimization of cable-stayed bridges with three-dimensional modelling.Computers and Structures 1997;64(14):741±58.[6] Wang PH, Tseng TC, Yang CG. Initial shape of cable-stayed bridges. Computers and Structures 1993;46(6):1095±106.[7] Wang XW, Xin XZ, Pan JY, Cheng QG. Determination ofrational cable forces under dead load of prestressed concrete cable-stayed bridges. Bridge Construction 1996;4:1±5 (in Chinese).[8] Xiao RC, Xiang HF. Optimization of cable forces incable-stayed bridges using the method of in¯uence matrix. In: Proceedings of the 12th National Conference of Bridge Engineering, Guang Zhou, 1996. p. 547±55 (in Chinese).。
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。
桥梁工程专业毕业设计中英文摘要
桥梁工程专业毕业设计中英文摘要本桥为跨狮狸沟而设，本桥上部结构为二联2-40m+一联3-50mT梁，T梁采用先简支后连续结构。
本桥位于直线上，纵向位于+0.8%上坡段，设计荷载为一级，桥面宽度为净9附2×2.0m人行道，设计洪水频率为1/100，基本地震烈度为Ⅶ级。
墩台方向均按路线方向布置。
桥面采用15cm混凝土铺装，FYT-1防水层，9cm沥青混凝土。
上部结构进行了截面尺寸的拟定，梁桥自重和二期恒载的横载内力计算，活载内力计算，最不利荷载组合等，为下部结构的检算奠定基础。
下部结构采用钢筋混凝土柱式墩，板式空心墩。
基础采用挖孔灌注桩和钻孔灌柱桩。
本设计采用容许应力法对此桥下部结构进行设计并检算。
对基础，承台按刚性承台板进行设计计算，对桩分别按土的阻力和桩身材料强度计算单桩轴向容许承载力，检算外荷载作用下桩身稳定性和材料强度，检算桩的抗裂性。
并对桥墩进行基础沉降和墩顶水平位移检算。
最终的计算结果表明，上述所有各项检算均符合各相关规定要求。
关键词：桥梁下部结构桥墩桩This bridge supposes for the cross lion fox ditch, The bridge structure for the combined 2-40m + a joint 3 - 50m beam，T-beam used in simple and continuous support structure. The bridge is located in straight line, vertical +0.8% at the uphill, Design of a load, the bridge deck width of the net with two 9 ×2.0m sidewalks, design flood frequency of 1 / 100, for the basic seismic intensity Ⅶ level. A pillar direction presses the route direction arrangement. The bridge floor uses the 15cm concrete paving, the FYT-1 waterproof layer, the9cm asphalt concrete.The superstructure carried on section size drawing up, the beam bridge has been self-possessed with two issue of deadloads lateral load endogen force computations, the live load endogen force computation, the most disadvantageous load combination and so on ,examined for the substructure calculated laid the foundation。
毕业设计混凝土桥梁结构形式(中英文翻译)
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。
从使用标准组成的小跨径桥梁到吊梁和跨径将近100英尺的连续箱梁桥，几乎所有的混凝土桥梁，甚至于相对短时间的桥梁都是预应力结构的。
采用预制、现场浇筑或两种方法并用。
在同一工程中经常同时使用先张法和后张法。
在美国，公路桥一般情况下必须满足荷载、设计和AASHTO规定的建设的要求。
对于服务于其它目的步行街和桥梁的设计要求由当地的或地方的代码建立。
ACI代码的备注也被纳入参考。
伴随最小交通中断的大约100英尺的跨径的桥梁由提供低的初级预算，最小量维修和养护费用和快速的简易的预制板组成。
这种梁一般是用先张法。
预制板一块挨一块的放置并且在相邻的预制板间受剪的缝隙填满不收缩的灰泥之后，经常在中间横膈膜的位置后张拉。
对于公路，用沥青铺设的表面可以直接用在预制混凝土的上面。
在某些情况下，一块放置在正确位置的现浇板提供复合作用。
空心板一般用于深度15英尺到21英尺，宽度3英尺或4英尺。
对于一个标准HS20的公路，空心板适合于大约50 英尺的跨径。
标准渠化区段在多种宽度，深度从21英尺到35英尺时是有利的，可用于大约20英尺到60英尺的跨径。
中空的箱形梁和T形梁用于大约100英尺的长跨径。
对于中等跨径的大约120英尺的公路桥，一般使用AASHTO 标准梁。
它们和一种复合现场预制行车道板一起使用。
在板被安置之后，这样的梁经常在预浇梁的先张拉与合成梁的后张拉后结合。
试图获得改进经济，一些国家已经采用更精炼的设计，例如华盛顿州标准梁。
经过特别设计预制建筑梁可以用来携带一个单轨铁路系统。
完成的沃尔特迪斯尼乐园单轨铁路的一系列的特征, 每个包括六个单独支持的预拉梁，一起形成连续结构。
典型的跨距是100到110英尺。
被使用的337根梁，大约一半有垂直与水平曲率和易变超级升高的一些结合。
所有的梁是中空的，它的特征是通过在曲梁中插入泡沫和在直梁制作中移动形心轴获得。
毕设必备道路桥梁专业毕业设计英文翻译(英文原文+中文翻译)
Accident Analysis and PreventionThis paper describes a project undertaken to establish a self-explaining roads (SER) design programmeon existing streets in an urban area. The methodology focussed on developing a process to identifyfunctional road categories and designs based on endemic road characteristics taken from functionalexemplars in the study area. The study area was divided into two sections, one to receive SER treatments designed to maximise visual differences between road categories, and a matched control area to remainuntreated for purposes of comparison. The SER design for local roads included increased landscaping andcommunity islands to limit forward visibility, and removal of road markings to create a visually distinctroad environment. In comparison, roads categorised as collectors received increased delineation, additionof cycle lanes, and improved amenity for pedestrians. Speed data collected 3 months after implementationshowed a significant reduction in vehicle speeds on local roads and increased homogeneity of speeds onboth local and collector roads. The objective speed data, combined with r esidents’ speed choice ratings,indicated that the project was successful in creating two discriminably different road categories.2010 Elsevier Ltd. All rights reserved.1. Introduction1.1. BackgroundChanging the visual characteristics of roads to influencedriver behaviour has come to be called the self-explaining roads(SER) approach (Theeuwes, 1998; Theeuwes and Godthelp, 1995;Rothengatter, 1999). Sometimes referred to as sustainable safety,as applied in the Netherlands, the logic behind the approach isthe use of road designs that evoke correct expectations and drivingbehaviours from road users (Wegman et al., 2005; Weller etal., 2008). The SER approach focuses on the three key principlesof functionality, homogeneity, and predictability (van Vliet andSchermers, 2000). In practice, functionality requires the creation ofa few well-defined road categories (e.g., through roads, distributorroads, and access roads) and ensuring that the use of a particularroad matches its intended function. Multifunctional roadslead to contradictory design requirements, confusion in the mindsof drivers, and incorrect expectations and inappropriate drivingbehaviour. Clearly defined road categories promote homogeneity intheir use and prevent large differences in vehicle speed, direction,and mass. Finally, predictability, or recognisability, means keepingthe road design and layout within each category as uniform as possibleand clearly differentiated from other categories so that thefunction of a road is easily recognised and will elicit the correctbehaviour from road users. The SER approach has been pursued tothe largest extent in the Netherlands and the United Kingdom but ithas also been of some interest inNewZealand. In 2004, the NationalRoad Safety Committee and the Ministry of Transport articulateda new National Speed Management Initiative which stated “Theemphas is is not just on speed limit enforcement, it includes perceptualmeasures that influence the speed that a driver feels is appropriatefor the section of road upon which they are driving–in effect the ‘selfexplainingroad”’ (New Zealand Ministry of Transport, 2004).In cognitive psychological terms, the SER approach attempts toimprove road safety via two complementary avenues. The first is toidentify and use road designs that afford desirable driver behaviour.Perceptual properties such as road markings, delineated lane width,and roadside objects can function as affordances that serve as builtininstructions and guide driver behaviour, either implicitly orexplicitly (Charlton, 2007a; Elliott et al., 2003; Weller et al., 2008).This work is more or less a direct development of work on perceptualcountermeasures, perceptual cues in the roading environmentthat imply or suggest a particular speed or lane position, eitherattentionally or perceptually (Charlton, 2004, 2007b; Godley et al.,1999).A second aspect of the SER approach is to establish mentalschemata and scripts, memory representations that will allowroad users to easily categorise the type of road on which they are.1.2. Localised speed managementThe traditional approaches to improving speed management,traffic calming and local area traffic management (LATM) havefocussed on treating specific problem locations or “black spots”in response to crash occurrences or complaints from the public(Ewing, 1999). A potential disadvantage of these approaches is thataddressing the problem with localised treatments can lead to are-emergence of the problem at another location nearby. Further,when applied inappropriately, localised approaches may addressthe problem from only one perspective, without considering theimpact on other types of road users or residents. When traffic calmingtreatments rely on physical obstacles such as speed humpsthey can be very unpopular with bothresidents and road users andcan create new problems associated with noise, maintenance, andvandalism (Martens et al., 1997).From an SER perspective, treatments that are highly localizedor idiosyncratic may do more harm than good by adding to themultiplicity of road categories and driver uncertainty, rather thanbuilding driver expectations around a few uniform road types.Instead of considering a single location in isolation, SER roaddesigns are considered within a hierarchy of road functions; e.g.,access roads, collector roads, and arterial roads. Although SERschemes may employ physical design elements used in trafficcalming schemes (e.g., road narrowing with chicanes and accesscontrols) they also employ a range of more visually oriented featuressuch as median and edge line treatments, road markings,pavement surfaces, and roadside furniture. For an effective SERscheme it is important to select the combination of features that will afford the desired driver speeds and to ensure their consistentuse to form distinct categories of road types (van der Horst andKaptein, 1998; Wegman et al., 2005).road category that would meet the three SER principles of functional use, homogeneous use, and predictable use. Herrstedt (2006)reported on the use of a standardised catalogue of treatments compiledfrom researcher and practitioner advice. Goldenbeld and vanSchagen (2007) used a survey technique to determine road characteristicsthat minimise the difference between drivers’ ratingsof preferred speed and perceived safe speed and select road featuresthat make posted speeds “credible”. Aarts and Davidse (2007)used a driving simulator to verify whether the “essential recognisabilitycharacteristics” of different road classes conformed to theexpectations of road users. Weller et al. (2008) employed a range of statistical techniques, including factor analysis and categoricalclustering to establish the road characteristics that drivers use tocategorise different road types.The practical difficulties of implementing an SER system thusbecome a matter of finding answers to a series of questions. Howdoes one create a discriminable road hierarchy for an existingroad network? What road characteristics should be manipulatedto establish category-defining road features? How can SER roadfeatures and selection methods be made relevant and appropriatefor a local context? (Roaddesigns appropriate for The Netherlandswould not be suitable in New Zealand, in spite of its name.) A surveyof national and international expert opinion in order establishcategory-defining road features for New Zealand roads revealedthat the regional character and local topography of roads oftenundercut the usefulness of any standardised catalogue of designcharacteristics (Charlton and Baas, 2006).1.4. Goals of the present projectThe project described in this paper sought to develop anddemonstrate an SER process based on retrofitting existing roadsto establish a clear multi-level road hierarchy with appropriatedesign speeds, ensuring that each level in the hierarchy possesseda different “look and feel”. Rather than transferring SER designs already in use internationally, the project attempted to develop amethod that would build on the features of roads in the local area;extending road characteristics with desirable affordances to otherroads lacking them and creating discriminable road categories inthe process. Of interest was whether such a process could producecost-effective designs and whether those designs would be effectivein creating different road user expectations and distinct speedprofiles for roads of different categories.2. MethodsThe research methodology/SER design process developed forthis project progressed through a series of five stages: (1) selectionof study area; (2) identification of the road hierarchy; (3) analysisof the road features; (4) development of a design template; and (5)implementation and evaluation of the SER treatments. Each of thestages is described in the sections that follow.2.1. Selection of study areaThe study area for this project (Pt England/Glen Innes in Auckland)was selected in consultation with a project steering groupcomprised of representatives from the Ministry of Transport, NewZealand Transport Agency, New Zealand Police, and other localtransport and urban agencies. The study area was an establishedneighbourhood contained amix of private residences, small shops,schools, and churches, and was selected, in part, because of its historyof cyclist, pedestrian and loss of controlcrashes, almost twicethe number。
混凝土工程中英文(个人整理)
混凝土工程concrete works一、材料袋装水泥bagged cement散装水泥bulk cement砂sand骨料aggregate商品混凝土commercial concrete现浇混凝土concrete-in-situ预制混凝土precast concrete预埋件embedment（fit 安装）外加剂admixtures抗渗混凝土waterproofing concrete石场aggregate quarry垫块spacer二、施工机械及工具搅拌机mixer振动器vibrator电动振动器electrical vibrator振动棒vibrator bar抹子（steel wood）trowel磨光机glasser混凝土泵送机concrete pump橡胶圈rubber ring夹子clip混凝土运输车mixer truck自动搅拌站auto-batching plant输送机conveyor塔吊tower crane汽车式吊车motor crane铲子shovel水枪jetting water橡胶轮胎rubber tires布袋cloth-bags塑料水管plastic tubes喷水雾spray water fog三、构件及其他专业名称截面尺寸section size（section dimension）混凝土梁concrete girder简支梁simple supported beam挑梁cantilever beam悬挑板cantilevered slab檐板eaves board封口梁joint girder翻梁upstand beam楼板floor slab空调板AC board飘窗bay window（suspending window）振捣vibration串筒a chain of funnels混凝土施工缝concrete joint水灰比ratio of water and cement砂率sand ratio大体积混凝土large quantity of pouring混凝土配合比concrete mixture rate混凝土硬化hardening of concrete(in a hardening process 硬化中)规定时间regulated period质保文件quality assurance program设计强度design strength永久工程permanent works临时工程temporary works四、质量控制及检测不符合规格的non-standard有机物organic matters粘土clay含水率moisture content（water content）中心线central line安定性soundness （good soundness 优良的安定性）坍落度slump (the concrete with 18m m±20mm slump)混凝土养护concrete curing标养混凝土试件standard curing concrete test sample同条件混凝土试件field-cure specimen收缩shrinkage初凝时间initial setting time终凝时间final setting time成品保护finished product protection混凝土试件concrete cube偏心受压eccentric pressing保护层concrete cover孔洞hole裂缝crack蜂窝honeycomb五、句子1，Usually we control the cement within 2% 我们将水泥的误差控制在2%2，Are there any pipe clogging happened during the concreting?浇筑混凝土中有堵管现象吗？3，Will the pipe be worn out very fast？管道磨损很快吗？4，This embedment is fixed at 1500mm from the floor and 350mm from the left edge of the column. Would you measure the dimension by this meter?预埋件的位置在地面上1500mm，离柱边350mm。
混凝土毕业设计论文中英文对照资料外文翻译文献
外文文献及译文目录•1历史•2组成o水泥2.1o 2.2水o 2.3骨料o 2.4化学外加剂o 2.5掺合料和水泥混合o 2.6纤维•3搅拌混凝土•4个特点o 4.1和易o 4.2固化o 4.3强度o 4.4弹性o 4.5扩张和收缩o 4.6开裂▪ 4.6.1收缩裂缝▪ 4.6.2拉裂o 4.7蠕变•5损伤模式o 5.1火灾o 5.2总量扩张o 5.3海水效果o 5.4细菌腐蚀o 5.5化学武器袭击▪ 5.5.1碳化▪ 5.5.2氯化物▪ 5.5.3硫酸盐o 5.6浸出o 5.7人身损害•6种混凝土o 6.1普通混凝土o 6.2高强混凝土o 6.3高性能混凝土o 6.4自密实混凝土o 6.5喷浆o 6.6透水性混凝土o 6.7混凝土蜂窝o 6.8软木复合水泥o 6.9碾压混凝土o 6.10玻璃混凝土o 6.11沥青混凝土•7混凝土测试•8混凝土回收•9使用混凝土结构o9.1大体积混凝土结构o9.2钢筋混凝土结构o9.3预应力混凝土结构•10参见•11参考•12外部链接历史在塞尔维亚,仍然是一个小屋追溯到5600bce已经发现,同一个楼层发红色石灰,沙子和砾石。
金字塔陕西中建千多年前,含有石灰和火山灰.或粘土。
碎石水和泥浆僵硬和发展实力超过时间。
为了确保经济实用的解决方案,既罚款又粗骨料使用,以弥补大部分的混凝土混合物。
砂,天然砾石及碎石,主要用于这一目的。
不过,现在越来越普遍,再生骨料(由建筑,拆卸和挖掘废物)被用作局部代替天然骨料,而一些生产总量包括风冷高炉炉渣和粉煤灰也是不允许的。
装饰石材等石英岩,潆石块或玻璃破碎,有时添加到混凝土表面进行装饰性"的总暴露"完成,流行景观设计师。
化学外加剂化学外加剂现形式的材料粉末或液体,补充了混凝土给它的某些特性没有可与普通混凝土混合物。
在正常情况下使用,外加剂剂量均低于5%的大量水泥,并补充了混凝土当时的配料/混合.最常见的外加剂有:加速器加速水化(硬化)的混凝土。
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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。
从使用标准组成的小跨径桥梁到吊梁和跨径将近100英尺的连续箱梁桥，几乎所有的混凝土桥梁，甚至于相对短时间的桥梁都是预应力结构的。
采用预制、现场浇筑或两种方法并用。
在同一工程中经常同时使用先张法和后张法。
在美国，公路桥一般情况下必须满足荷载、设计和AASHTO规定的建设的要求。
对于服务于其它目的步行街和桥梁的设计要求由当地的或地方的代码建立。
ACI代码的备注也被纳入参考。
伴随最小交通中断的大约100英尺的跨径的桥梁由提供低的初级预算，最小量维修和养护费用和快速的简易的预制板组成。
这种梁一般是用先张法。
预制板一块挨一块的放置并且在相邻的预制板间受剪的缝隙填满不收缩的灰泥之后，经常在中间横膈膜的位置后张拉。
对于公路，用沥青铺设的表面可以直接用在预制混凝土的上面。
在某些情况下，一块放置在正确位置的现浇板提供复合作用。
空心板一般用于深度15英尺到21英尺，宽度3英尺或4英尺。
对于一个标准HS20的公路，空心板适合于大约50 英尺的跨径。
标准渠化区段在多种宽度，深度从21英尺到35英尺时是有利的，可用于大约20英尺到60英尺的跨径。
中空的箱形梁和T形梁用于大约100英尺的长跨径。
对于中等跨径的大约120英尺的公路桥，一般使用AASHTO 标准梁。
它们和一种复合现场预制行车道板一起使用。
在板被安置之后，这样的梁经常在预浇梁的先张拉与合成梁的后张拉后结合。
试图获得改进经济，一些国家已经采用更精炼的设计，例如华盛顿州标准梁。
经过特别设计预制建筑梁可以用来携带一个单轨铁路系统。
完成的沃尔特迪斯尼乐园单轨铁路的一系列的特征, 每个包括六个单独支持的预拉梁，一起形成连续结构。
典型的跨距是100到110英尺。
被使用的337根梁，大约一半有垂直与水平曲率和易变超级升高的一些结合。
所有的梁是中空的，它的特征是通过在曲梁中插入泡沫和在直梁制作中移动形心轴获得。
由于运输问题和构件垂直的大而重的问题，预制梁不能用于跨径超过120英尺的桥梁。
另一方面，桥梁有一种向大跨径发展的明显趋势。
对于提高的都市高速道路来说，大跨径促进通路而且将对下面的活动妨碍减到最少。
对环境的损害问题的关心，导致连续高架桥大跨径的选择。
对于跨河桥，因为航行间隙的需求，中间可能不可以搭设桥墩。
在这一个类型的典型建筑中，桥墩（台）采用现场预制, 经常使用滑动的技术。
一个箱梁的" 锤头"浇筑在桥墩的顶端, 并且通过平衡的悬臂方法控制每个方向的建筑进行。
最后,在完成跨中结合处的浇筑之后, 这种结构对于完全连续性的桥梁来说是进一步的受拉的。
修剪钥匙可能被用在片段之间垂直面之上, 而且预制建筑与环氧基树脂黏在一起。
想象的工程学藉着许多特别的技术示范已经延长混凝土建筑的范围，就桥梁而言，已经远远超过几年以前可以想象的到的任何事。
在美国，双向弯曲的现场浇铸的部分箱梁已经成功地完成310 英尺的跨距，跨越了北加州的鳗鱼河。
该桥的中间跨度550英尺，侧跨跨度390英尺，初步设计已经完成。
预应力混凝土桥梁很适合于大跨径的另一种形式是悬索箱梁。
一个值得注意的例子是阿根廷境内的Chaco-Corrientes桥。
桥的主跨径804英尺，由两个A型构架塔支撑，悬索从塔顶到沿着底板伸展。
受拉的悬索不仅提供一种垂直反应组成支撑底板，而且对于箱梁产生水平的压缩，增加构件中的张拉力。
许多年以前德国工程师Ulrich Finsterwalder 提出适合于负担荷载和大跨径的一个结构类型是压带式桥。
压带是桥运输跨越莱茵河的一个管道和人行道，跨径446英尺。
上部结构的施工顺序是（a）垂直的一对悬索，(b)在每个悬索的下面，安置预制板形成一人行道甲板和一U型的平台, 并且(c)在附近现场浇注混凝土。
放置在顶部的管道支撑在扶手的顶部，向一边倾斜，大幅地增加结构的主要风速。
讨论桥梁形式应适当的考虑结构的美学。
当结构可能根据最小的费用和技术设计的时候，时间消逝了。
特别是桥梁结构到处可见。
生产视觉上不愉快的结构, 过去经常发生, 是一种不负专业责任的行为。
特别地对于主要的跨距，还有一些比较普通的结构来说，应该在设计过程的概念阶段寻找建筑的建议。
出处：安瑞克．混凝土桥梁结构形式[J]．建筑实录(美)，2010，33(36)：34—36The 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 aregenerally 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 .All beams 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 onlyprovide 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 is past 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.。