专业英语(土木工程方案路桥方向)李嘉第三版翻译中英对照

土木工程专业英语翻译第一篇：土木工程专业英语翻译1.第一课土木工程，这个最古老的工程专业，是指对被建设环境的规划、设计、建筑和管理。

这个环境包括按科学原理所建的一切结构，从灌溉和排水系统到火箭发射设备。

土木工程师们修路、建桥、打隧道，木工程师始终（将介词throughout转译成副词）都要充分利用计算机。

用计算机来设计工程的各要素（计算机辅助设计CAD）且用计算机来管理这个工程项目。

对于现代土木工程师而言，计算机是必备的工具，因为它们允许工程师高效建水坝，海港，发电厂，供水排水系统，建医院，学校，公共交通设施和其他公共设施实质上就是要建设现代化社会和大量人口集中地。

他们也建设私有的设施，例如：机场，铁路，管线，摩天大楼，和其他大型建筑物，它们设计用于工业，商业和居住等用途。

此外，土木工程师规划，设计和建设完整的城市和乡镇，近年来，已经在规划和设计空间平台来构建自给自足型社区。

2.土木这个词来源于拉丁文，原意是市民。

1782年，英国人JohnSmeaton用这个术语将非军事工程工作从在当时占绝大多数的军事工程师所人事的工程工作中区别开来。

从那以后，土木工程这个词常常用于表示建设公用设施的工程师们所人事的工作，尽管这个领域要宽广得多。

3.范围：因为它的面太广，所以土木工程被分成许多技术专业。

各专业的土木工程专家所需要的技能取决于工程项目的类型。

当一个项目开始时，场地被土木工程师所测绘，他们给定给水排水设施和电力线路的实际位置。

岩土工程专家们完成土壤实验来确定地基是否能承受工程项目的自重。

环境专家们研究项目对当地的影响：潜在的空气和地下水资源的污染，工程项目对当地动植物的影响，为满足保护环境的管理要求，怎样才能把工程项目设计好。

4.对于任何一个给定的工程项目，土地处理大量的用来制定工程最佳施工方法的数据。

5.结构工程.在这个专业中，土木工程师计划和设计各种各样的结构，包括桥，水坝，发电厂，设备的支柱，海岸工程的特殊结构，美国空间项目，发射塔，巨大的天文射电望远镜，和许多种其它的工程项目。

专业外语土木工程专业（路桥方向）汉译英Lesson 71.发货人和旅行者根据所提供的服务水平选择交通运输方式。

The shippers and travelers select transportation modes in terms of level of service provided.2.术语服务水平是用来表述道路为交通服务的质量。

The term level of service is used to describe the quality of service that is provided for the traffic by the roads.3.因为时间紧迫，他们选择用航空方式运输这些紧急物资。

They selected air transportation to carry these important goods since time was a premium.4.公路运输具有机动灵活并能提供门到门服务的特点。

Highway transportation has the advantages of flexibility and ability to provide door-to-door service.5.我国公路运输网的主要骨架是由12条限制出入的高速公路组成。

The backbone of highway transportation network comprises of 12 limited-access freeways in our country.Lesson 81.公路定线包括现有资料的室内研究、路线踏勘测量、初步定线和最终定线四个阶段。

The highway location involves four phrases: office study of existing information, reconnaissance survey of routes, preliminary location and final location.2.一个独一无二的桥位或者一座山的垭口都可能成为一个主要的控制点。

土木工程专业英语课文_翻译_考试必备土木工程专业英语课文翻译The principal construction materials of earlier times were wood and masonry brick, stone, or tile, and similar materials. The courses or layers were bound together with mortar or bitumen, a tar like substance, or some other binding agent. The Greeks and Romanssometimes used iron rods or claps to strengthen their building. The columns of the Parthenon in Athens, for example, have holes drilled in them for iron bars that have now rusted away. The Romans also used a natural cement called puzzling, made from volcanic ash, that became as hard as stone under water.早期时代的主要施工材料,木材和砌体砖,石,或瓷砖,和类似的材料;这些课程或层密切联系在一起,用砂浆或沥青,焦油一个样物质,或其他一些有约束力的代理人;希腊人和罗马人有时用铁棍或拍手以加强其建设;在雅典的帕台农神庙列,例如,在他们的铁钻的酒吧现在已经生锈了孔;罗马人还使用了天然水泥称为令人费解的,由火山灰制成,变得像石头一样坚硬在水中;Both steel and cement, the two most important construction materials of modern times, were introduced in the nineteenth century. Steel, basically an alloy of iron and a small amount of carbon had been made up to that time by a laborious process that restricted it to such special uses as sword blades. After the invention of the Bessemer process in 1856, steel was available in large quantities at low prices. The enormous advantage of steel is its tensile force which, as we have seen, tends to pull apart many materials. New alloys have further, which is a tendency for it to weaken as a result of continual changes in stress.钢铁和水泥,两个最重要的现代建筑材料,介绍了在十九世纪;钢,铁,基本上是少量的碳合金已作出了这一由一个艰苦的过程,限制它的刀刃等特殊用途的时间;后在1856年发明贝塞麦过程,钢在低价格大批量供货;钢铁的巨大优势是它的拉伸力,正如我们所看到的,往往会拉开许多材料;新合金进一步,这是一个趋势,它削弱了在压力不断变化的结果;Modern cement, called Portland cement, was invented in 1824. It is a mixture of limestone and clay, which is heated and then ground into a power. It is mixed at or near the construction site with sand, aggregate small stones, crushed rock, or gravel, and water to make concrete. Different proportions of the ingredients produce concrete with different strength and weight. Concrete is very versatile; it can be poured, pumped, or even sprayed into all kinds of shapes. And whereas steel has great tensile strength, concrete has great strength under compression. Thus, the two substances complement each other. 现代水泥,称为硅酸盐水泥,发明于1824年;它是石灰石和粘土的混合物,被加热,然后进入电源地;它是混合达到或接近沙施工现场,聚集的小石头,碎石,或石子和水,使混凝土;不同比例的成分产生不同强度和重量混凝土;混凝土是非常灵活,它可浇,泵浦,或连成各种形状喷洒;和鉴于钢具有很大的拉伸强度,混凝土受压的伟大力量;因此,这两种物质是相辅相成的;They also complement each other in another way: they have almost the same rate of contraction and expansion. They therefore can work together in situations where both compression and tension are factors. Steel rods are embedded in concrete to make reinforced concrete in concrete beams or structures where tensions will develop. Concrete and steel also form such a strong bond the force that unites them that the steel cannot slip within theconcrete. Still another advantage is that steel does not rust in concrete. Acid corrodessteel, whereas concrete has an alkaline chemical reaction, the oppositeof acid.他们还以另一种方式补充对方:他们几乎在同样的速度收缩和扩张;因此,他们可以一起工作的情况下压缩和紧张的因素;钢条是嵌在混凝土,使钢筋混凝土结构中混凝土梁或地方的紧张局势会发展;混凝土和钢也形成如此强烈的纽带团结的力量他们的钢材,不滑内的混凝土;还有一个好处是,不生锈的钢混凝土;酸腐蚀钢,而混凝土的碱性化学反应,酸相反;The adoption of structural steel and reinforced concrete caused major changes in traditional construction practices. It was no longer necessary to use thick walls of stone or brick for multistory buildings, and it became much simpler to build fire-resistant floors. Both these changes served to reduce the cost of construction. It also became possible to erect buildings with greater heights and longer spans.结构钢和钢筋混凝土建筑采用传统的做法造成了重大变化;它不再需要使用的石块或砖头厚的多层建筑物的墙壁,成为更简单,建立防火地板;这些变化都有助于降低建设成本;它也成为可能有更大的直立高度和时间跨度的建筑;Since the weight of modern structures is carried by the steel or concrete frame, the walls do not support the building. They have become curtain walls, which keep out the weather and let in light. In the earlier steel orconcrete frame building, the curtain walls were generally made of masonry; they had the solid look of bearing walls. Today, however, curtain walls are often made of lightweight materials such as glass, aluminum, or plastic, in various combinations. 由于现代结构重量是由钢或混凝土框架进行,墙壁不支持建设;他们已成为玻璃幕墙,它保持了天气和光线让;在早期的钢或混凝土框架结构,玻璃幕墙,一般由砖石,他们有坚实的承重墙看看;然而,今天,玻璃幕墙往往是由诸如玻璃,铝,塑料或轻质材料,在各种组合;Another advance in steel construction is the method of fastening together the beams. For many years the standard method was riveting. A rivet is abolt with a head that looks like a blunt screw without threads. It is heated, placed in holes through the pieces of steel, and a second head is formed at the other end by hammering it to hold it in place. Riveting has now largely been replaced by welding, thejoining together of pieces of steel by melting a steel material between them under high heat.钢结构建筑的另一个进步是梁紧固在一起的方法;多年来,标准方法是铆;铆钉是一个头,像一个没有线程看起来钝螺丝螺栓;它被加热时,通过放置在洞的钢件,第二头在另一端形成的锤击它举行到位;铆接现在很大程度上是由焊接取代,加入钢件在一起融化在高温下它们之间的钢铁材料;Presstressed concrete is an improved form of reinforcement. Steel rodsare bent into the shapes to give them the necessary degree of tensile strengths. They are then used to priestess concrete, usually by one of two different methods. The first is to leave channels in a concrete beam that correspond to the shapes of the steel rods. When the rods are run throughthe channels, they are then bonded to the concrete by filling the channels with grout, a thin mortar or binding agent. In the other and more common method, the priestesses steel rods are placed in the lower part of a formthat corresponds to the shape of the finished structure, and the concrete is poured around them. Priestess’s concrete uses less steel and less concrete. Because it is a highly desirable material.预应力钢筋混凝土是一种改进形式;棒钢弯曲成的形状,给他们一定程度的拉伸强度;然后他们用女祭司混凝土,由两种不同的方法之一,通常;首先是留在渠道混凝土梁对应于钢铁棒的形状;当棒是通过渠道来说,他们是那么粘在混凝土充填灌浆,薄砂浆或结合剂的渠道;在其他更常见的方法,女祭司钢棒放置在一个表格对应的成品下部结构形状,和他们周围的混凝土浇;女祭司的具体使用较少的钢铁和混凝土少;因为它是一个非常可取的材料;Presstressed concrete has made it possible to develop buildings with unusual shapes, like some of the modern, sports arenas, with large spaces unbroken by any obstructing supports. The uses for this relatively new structural method are constantly being developed. 预应力混凝土使人们有可能发展不寻常的形状的建筑物,如现代,体育场一些大空间的任何阻挠支持不间断;在使用这种相对较新的构造方法正在不断发展;。

Lesson 1 Careers in Civil Engineering(土木工程中的各种业务)土木工程是一个意味着工程师必须要经过专门的大学教育的职业。

许多政府管辖部门还有（一套）认证程序，这一程序要求工科毕业生在他们能积极地开始（从事）他们的事业之前，通过（认证）考试, 这种考试类似于律师职业里的律师考试一样。

大学里, 工科课程中着重强调数学、物理, 和化学,尤其在开始的二到三年。

在工科所有分支中，数学非常重要, 因此它被着重地强调。

今天, 数学包括统计学中的课程主要涉及集合, 分类, 和使用数字数据, 或信息。

统计数学的一个重要方面是概率, 它涉及当有改变问题的结果的不同的因素, 或变量时，可能会发生什么。

例如，在承担桥梁的建设之前, 运用统计研究来预计未来桥梁期望承受的交通量. 在桥梁的设计中，(各种)变量如作用在基础上的水压, 碰撞, 不同的风力的作用, 以及许多其它因素必须考虑。

由于在解决这些问题涉及大量的计算, 现在几乎所有工科课程中都包括计算机编程。

当然,计算机能比人类以更快的速度和准确性解决许多问题。

但如果不给计算机清楚和准确指令和信息，换句话说，一个好程序，它也是无用的。

虽然，在工科课程中，对技术科目着重强调，但当前的趋势还是要求学生学习社会科学和语言艺术的课程。

工程和社会间的关系变得更加紧密; 因此,再一次充分说明, 工程师负责（承担）的工程在许多不同和重要的方面影响社会,这些方面是他们所知道的。

并且，工程师需要一种很肯定（自信）语言表达方式来准备报告，这个报告要清楚明了，且在多数情况下, 是令人信服的。

参与研究的工程师要能为科学出版物详细描述他们的发现。

最后两年的工科课程计划包括学生专业领域的学科。

为准备使学生成为一名土木工程师, 这些专业课程可能会涉及诸如大地测量、土力学，或水力学。

学生在大学中的最后一年前常常就开始了频繁的工程师招聘。

近年来，许多不同的公司和政府机构为争夺工程师而竞争。

Lesson 7 Transportation Systems交通运输系统Transportation system in a developed nation consists of a network of modes that have evolved over many years. The system consists of vehicles, guideways, terminal facilities and control systems: these operate according to established procedures and schedules in the air, on land, and on water. The system also requires interaction with the user, the operator and the environment. The systems that are in place reflect the multitude of decisions made by shippers, carriers, government, individual travelers, and affected nonusers concerning the investment in or the use of transportation. The transportation system that has evolved has produced a variety of modes that complement each other.在发达国家，交通运输系统由网状结构组成的模式已经发展了好多年。

这个系统由交通工具、轨道、站场设施和控制系统组成。

这些依照空中、陆上和水上已制定的程序和计划运转。

这个系统也需要和用户、司机和环境互动。

Civil EngineeringCivil engineering, the oldest of the engineering specialties, is the planning, design, construction, and management of the built environment. This environment includes all structures built according to scientific principles, from irrigation and drainage systems to rocket-launching facilities.土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。

此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。

Civil engineers build roads, bridges, tunnels, dams, harbors, power plants, water and sewage systems, hospitals, schools, mass transit, and other public facilities essential to modern society and large population concentrations. They also build privately owned facilities such as airports, railroads, pipelines, skyscrapers, and other large structures designed for industrial, commercial, or residential use. In addition, civil engineers plan, design, and build complete cities and towns, and more recently have been planning and designing space platforms to house self-contained communities.土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。

1、土木工程中的各种业务1、土木工程中的各种业务Engineering is a prof ession, which means that an engineer must have a specialized university education. Many government jurisdictions also have licensing procedures which require engineering graduates to pass an examination, similar to the examination f or a lawyer, bef ore they can actively start on their careers.工程是一种专业，这就是说工程师必须受过专业大学教育。

许多政府管辖部门还有（一套）认证程序，这一程序要求工科毕业生在他们能积极地开始他们的职业生涯之前，通过（认证）考试, 这种考试类似于律师职业里的律师考试一样。

In the university, mathematics, physics, and chemistry are heavily emphasized throughout theengineering curriculum, but particularly in the f irst two or three years. Mathematic is very important in all branches of engineering, so it is greatly stressed. Today, mathematics includes courses in statistics, which deals with gathering, classif ying, and using numerical data, or pieces of inf ormation. An important aspect of statistical mathematics is probability, which deals with what may happen when there are dif f erent f actors, or variables, that can change the results of a problem. Bef ore the construction of a bridge is undertaken, f or example, a statistical study is made of the amount of traf f ic the bridge will be expected to handle. In the design of the bridge, variable such as water pressure on the f oundation, impact, the ef f ects of dif f erent wind f orces, and many other f actors must be considered.大学里,工科课程中着重强调数学、物理,和化学,尤其在开始的两到三年。

Civil EngineeringCivil engineering, the oldest of the engineering specialties, is the planning, design, construction, and management of the built environment. This environment includes all structures built according to scientific principles, from irrigation and drainage systems to rocket-launching facilities.土木工程学作为最老的工程技术学科，是指规划，设计，施工及对建筑环境的管理。

此处的环境包括建筑符合科学规范的所有结构，从灌溉和排水系统到火箭发射设施。

Civil engineers build roads, bridges, tunnels, dams, harbors, power plants, water and sewage systems, hospitals, schools, mass transit, and other public facilities essential to modern society and large population concentrations. They also build privately owned facilities such as airports, railroads, pipelines, skyscrapers, and other large structures designed for industrial, commercial, or residential use. In addition, civil engineers plan, design, and build complete cities and towns, and more recently have been planning and designing space platforms to house self-contained communities.土木工程师建造道路，桥梁，管道，大坝，海港，发电厂，给排水系统，医院，学校，公共交通和其他现代社会和大量人口集中地区的基础公共设施。

土木工程桥梁方向毕业设计外文及翻译(总13页)--本页仅作为文档封面，使用时请直接删除即可----内页可以根据需求调整合适字体及大小--学生姓名：学号：班级:专业：土木工程（桥梁方向）指导教师：2010 年 3 月What is traffic engineeringTraffic engineering is still a relatively new discipline within the overall bounds of civil engineering. it has nevertheless already been partially planning. the disciplines are not synonymous though. transportation planning is concerned with the planning, functional design, operation and management of facilities for any mode of transportation in order to provide for the safe, rapid, comfortable, convenient, economical and enviromenally-comparible movement of people and goods. within that broad scope, traffic engineering deals with those functions in respect of roads, road networks, terminal points , about lands and their relationships with other modes of transportation.Those definitions, based on the 1976 ones of the of transportation engineers are complete than, the British instituting of civil engineering which deals with traffic planning and design of roads, of frontage development and of parking facilities and with the control of traffic to provide safe, convenient and economical movement of vehicles and pedestrians.The definitions of the disicipline are becoming clearer: the methodology is developing continuously and becoming increasingly scientific. the early rule-of-thumb techniques are disappearing.Traffic problemThe discipline is young: the problem is large and still growing. in 1920 the total number of motor vehicles, licensed in great Britain was,650, year later the comparable figure was 14,950,000-a growth factor of 23 times. in recent years the rate of growth has slackened somewhat, but it is still considerable: 1955 6,466,0001960 9,439,0001965 12,938,0001970 14,950,0001974 17,247,000In order to see the problem in every day terms ,consider high street. anywhere. assuming that present trends continue, it is expected that within the next fifteen years of so the traffic on this road will increase by around forty to fifty persent. if this increased volume of traffic were to be accommodated at the same standard as today, the road might need to be widened by a similar forty to fifty percent-perhaps extra lane of traffic for the pedestrian to cross. In man cases, to accommodate the foreseeable future demand would destroy the character of the whole urban environment, and is clearly unacceptable.the traffic problem is of world-wide concern, but different countries are obviously at different stages in the traffic escalation-with America in the lead, while a county has few roads and a relatively low problem, as soon as the country is opened up by a road system, the standard of living and the demand for motor transport both rise, gathering momentum rapidly. eventually-and the stage at which this happens is open to considerable debate-the demand for cars, buses and lorries become satiated. the stage is known as saturation level.For comparison ,car ownership figures in different countries in 1970 were:India cars/personIsrael personJapan cars/personIreland cars/personNetherlands cars/personGreat Britain cars/personWest Germany cars/personAustralia cars/personUSA cars/personBut the growth in vehicle ownership is only part of the overall traffic problem. obviously,if a country has unlimited roads of extreme width, the traffic problem would not rise. no country in the world could meet this requirement: apart from anything else, it would not make economic for each vehicle using the roads. This figure is decreasing steadily.Three possible solutionsThe basic problem of traffic is therefore simple-an ever-increasing number of vehicles seeking to use too little roade space. the solution to the problem-is else a not-too-difficult choice from three possiblilities:build, sufficient roads of sufficient size to cope with the demand.Restrict the demand for roads by restricting the numbers of licensed vehicles.A compromise between (a) and (b) build some extra roads, using the and the existing road network to their full potential, and at the same time apply some restraint measures, limiting, the increase in demand as far as possible.With no visible end to the demand yet in sight, and 216 with modern road-making costs ranging around ￡1 million per kilometer cost of building roads in Britain to cope with an unrestricted demand would be far too great. added to this, such clossal use of space in a crowed island cannot be, seriously considered. in Los Angeles, a city built around the parking space for, the automobile. our citie are already largely built-and no one would consider ruining their character by pulling them down and rebuilding around the car, thus the first possible soluting is rule out.Even today,in an age of at least semi-affluence in most of the Western World, the car is still to some extent a status symbol, a symbol of family wants to own one, and takes steps saving or borrowing-to get one. as incomes and standards rise thesecond car becomes the target. any move to restrict the acquisition of the private car would be most unpopular-and politically unlikely.For many purpose the flexibility of the private car-conceptually affording door-to-door personal transport is ideal, and its use can be accommodate. for the mass, movement of people along specific corridors within a limited period of .. particularly the journey to work it may be less easily accommodated. other transport mode may be more efficient. some sort of compromise solution is the inevitable answer to the basic traffic problem .it is in the execution of the compromise solution that, traffic engineering comes into its own. traffic engineering ensures that any new facilities are not over-deigned and are correctly located to meet the demand. it ensures that the existing facilities are fully used, in the most efficient manner. the fulfillment of these duties may entail the selective throttling of demand: making the use of the car less attractive in the peak periods in order that the limited road space can be more efficiently used by public transport.Such restraint measures will often be accompanied by improvements in the public transport services, to accommodate the extra demand for them.Prestressed Concrete BridgesPrestressed concrete has been used extensively in . bridge construction since its first Introduction from Europe in the late 1940s. Literally thousands of highway bridges of both precast, prestressed concrete and cast-in-place post-tensioned concrete has been constructed in the United States. Railroad bridges utilizing prastressed concrete have become common as well. The use and evolution of prastressed concrete bridges is expected to continue in the years ahead.Short-span BridgesShort-span bridges will be assumed to have a maximum of 45 ft .It should be understood that this is an arbitrary figure, and there is no definite line of demarcation between short, moderate, and long spans in highway bridges. Short-span bridges are most efficiently made of precast ,prestressed-concrete hollow slabs, I-beams, solid slabs or cast-place solid slabs. and T-beams of relatively generous proportions.Precast solid slabs are most economical when used on very short spans. The slabs can be made in any convenient width,but widths of 3 or 4 ft to have been frequently are cast in the longitudinal sides of the precast units. After the slabs have been erected and the joints between the slabs have been filled with concrete, the keys transfer live load shear forces between the adjacent slabs.Precast hollow slabs used in short-span bridges may have round or square voids. They too are generally made in units 3 to 4 ft to m) wide with thicknesses from 18 to 27 in to . Precast hollow slabs can be made in any convenient width and depth, and frequently are used in bridges having spans from 20 to 50 ft to . Longitudinal shear keys are used in the joints between adjacent hollow slabs in the same way as with solid slabs. Hollow slabs may or may not be used with a composite, cast-in-place concrete topping an accecptable appearance and levelness.Transverse reinforcement normally is provided in precast concrete bridge superstructures for the purpose of tying the structure together in the transverse direction. Well-designed ties ensure that the individual longitudinal members forming the superstructure will act as a unit under the effects of the live load. In slab bridge construction, transverse ties most frequently consist of threaded steel bars placed through small holes formed transversely through the member during fabrication. Nuts frequently are used as fasteners at each end of the bars. In some instances, the transverse ties consist of post tensionedtendons placed, stressed, and grouted after the slabs have been erected. The transverse tie usually extends from one side of the bridge to the other.The shear forces imposed on the stringers in short-span bridges frequently are too large to be resisted by the concrete alone. Hence, shear reinforcement normally is required. The amount of shear reinforcement required may be relatively large if the webs of the stringers are relatively thin.Concrete diaphragms, reinforced with post-tensioned reinforcement or nonprestressed reinforcement, normally are provided transversely at the ends and at intermediate locations along the span in stringer-type bridges. The disaphragms ensure the lateral-distribution of the live load to the various stringers and prevent individual stringers from displacing or rotating significantly with respect to the adjacent stringers.No generalities will be made here about the relative cost of each of the above types of construction; construction costs are a function of many variables which prohibit meaningful generalizations. However, it should be noted that the stringer type of construction requires a considerably greater construction depth that is required for solid, hollow, or channel slab bridge superstructures. Stringer construction does not require a separate wearing surface, as do the precast slab types of construction, unless precast slabs are used to span between the stringers in lieu of the more commonly used cast-in-place reinforced concrete deck. Stringer construction frequently requires smaller quantities of superstructure materials than do slab bridges (unless the spans are very short). The construction time needed to complete a bridge after the precast members have been erected is greater with stringer framing than with the slab type of framing.Bridges Of Moderate SpanAgain for the purpose of this discussion only, moderate spans for bridges of prestressed concrete are defined as beingfrom 45 to 80 ft to . Prestressed concrete bridges in this span range generally can be divided into two types: stringer-type bridges and slab-type bridges. The majority of the precast prestressed concrete bridges constructed in the United States have been stringer bridges using I-shaped stringers, but a large number of precast prestressed concrete bridges have been constructed with precast hollow-box girders (sometimes also called stringers). Cast-in-place post-tensioned concrete has been used extensively in the construction of hollow-box girder bridges-a form of construction that can be considered to be a slab bridge.Stringer bridges, which employ a composite, cast-in-place deck slab, have been used in virtually all parts of the United States. These stringers normally are used at spacing s of about 5 to 6 ft to . The cast-in-place deck is generally from to in to in thickness. This type of framing is very much the same as that used on composite-stringer construction for short-span bridges.Diaphram details in moderate-span bridges are generally similar to those of the short spans, with the exception that two or three interior diaphragms sometime are used, rather than just one at midspan as in the short-span bridge.As in the case of short-span bridges, the minimum depth of construction in bridges of moderate span is obtained by using slab construction, which may be either solid – or hollow – box in cross section. Average construction depths are requires when stringers with large flanges are used in composite construction, and large construction depths are required when stringers with small bottom flanges are used. Composite construction may be developed through the use of cast-in-place concrete decks or with precast concrete decks. Lower quantities of materials normally are required with composite construction , and the dead weight of the superstructure normally is less for stringer construction than for slab construction.Long-Span BridgesPrestressed concrete bridges having spans of the order of 100ft are of the same general types of construction as structures having moderate span lengths, with the single exception that solid slabs are not used for long spans. The stringer spacings are frequently greater (with stringers at 7 to 9 ft) as the span lengths of bridges increase. Because of dead weight considerations, precast hollow-box construction generally is employed for spans of this length only when the depth of construction must be minimized. Cast-in-place post-tensioned hollow-box bridges with simple and continuous spans frequently are used for spans on the order of 100 ft and longer.Simple, precast, prestressed stringer construction would be economical in the United States in the spans up to 300 ft under some conditions. However, only limited use has been made of this type of construction on spans greater than 100 ft. For very long simple spans, the advantage of precasting frequently is nullified by the difficulties involved in handling, transporting, and erecing the girders, which may have depths as great as 10 ft and weigh over 200 tons. The exceptions to this occur on large projects where all of the spans are over water of sufficient depth and character that precast beams can be handled with floating equipment, when custom girder launchers can be used, and when segmental construction techniques can be used.The use of cast-in-place , post-tensioned, box-girder bridges has been extensive. Although structures of these types occasionally are used for spans less than 100ft, they more often are used for spans in excess of 100 ft and have been used in structuresHaving spans in excess of 300 ft. Structurally efficient in flexure, especially for continuous bridges, the box girder is torsionally stiff and hence an excellent type of structure for use on bridges that have horizontal curvature. Some governmental agencies use this form of construction almost exclusively in urban areas where appearance from underneath the superstructure,as well as from the side, is considered important.交通工程介绍什么是交通工程交通工程仍然是在土木工程的总的界限内的一种相对新的训练。