第1页：桥梁工程概述
Chapter 8 Bridge EngineeringBridges are great symbols of mankind’s conquest ofspace. It is a structure that spans obstacles, such asrivers, lakes, or gorges, to provide a roadway for traffic.By far the majority of bridges are designed to carryautomobile or railroad traffic, but some are intended forpedestrians only. Bridges also support pipes, troughs, orother conduits that transport materials, such as an oilpipeline or a water aqueduct.Section A Bridges（
桥梁工程）（桥梁）桥梁是人类征服空间的伟大象征，它跨越了许多障碍，比如河流、湖泊、峡谷，为交通提供了道路。到目前为止，大多数桥梁的功能是承担汽车和铁路交通，但也有一些为行人所用，另外，桥梁也支持管道、槽或其他运输材料的渠道，比如输油管或者水渡槽等。
第2页：桥梁的发展历史
- Humans have been constructing bridges since ancienttimes. For a few thousand years the classical form in bridgedesign has been the vault or arch. This structure, because ofits inherent contour, utilized masonry as its material.The useof concrete as a building material, however, was notconsidered until late in the nineteen century. The firstapplication of reinforced concrete to bridge structures waspioneered by Hennebique.
- 人类从远古时期就已经开始修建桥梁了。
近千年来拱桥一直是桥梁的传统形式，由于其固有的外形，这类结构可以利用砖石作为它的材料。直到19世纪后期，混凝土才被用作建筑材料。第一次把钢筋混凝土应用于桥梁结构的是Hemmebique。
第3页：预应力混凝土的应用
同一时期Jackson and Doehring提出了预应力混凝土的概念，但是由于混凝土收缩和徐变造成的高预应力损失使得它的应用并不成功。In the same period prestressed concrete concepts werebeing formulated by Jackson and Doehring. Thereapplication was not successful because of the high losses inprestress caused by shrinkage and creep of the concrete.Itwas not until 1926-1928 when Freyssinet was able to controlthese losses with high-strength steel that prestressing wasconsidered feasible.直到1926-1928年Freyssinet
采用高强度钢筋有效的控制了预应力损失，预应力结构才被认为是可行的。
第4页：预应力与钢材的推广
- Prestressedconcretewaswidelyuseforbridgesafterabout1950.Steelbecamemoreusefulforbridgeswiththedevelopmentofstrongerandmorecorrosion-resistantalloys.Aluminumalloys,whichwereusedinbridgesasearlyas1933,greatlyreducethedeadweightofthebridge,buttheyarenotwidelyusedbecausetheyarerelativelyexpensive.
- 预应力混凝土被广泛用于桥梁结构是在1950年以后了。
随着更大强度以及更加抗锈蚀合金的发展，钢材在桥梁上的应用也更加广泛了。铝合金早在1933年就应用于桥梁结构了，它极大的降低了桥梁的自重，但是由于造价昂贵并没有被广泛使用。
第5页：上部结构与下部结构
- The principal portions of a bridge may be said to be the“superstructure” and “substructure”([sʌb′strʌktʃə]n.下部结构). Thisdivision is used here simply for convenience, sine in manybridges there is no clear dividing line between the two.Bridges may also be classed as “deck”([dek]n.桥面，甲板，覆盖物；vt.装饰，修饰，打扮)or “through” types. In thedeck type(上承式) of bridge, the roadway is above the supportingstructure, that is, the load carrying elements of thesuperstructure are below the roadway.
- 桥梁的主要结构被称为上部结构和下部结构，这种划分方法用在这里只是为了方便起见，然而，在许多桥梁中这两者的界限是很不明显的。
桥梁也可以分为上承式和下承式。上承式桥梁的车道位于支撑结构之上，也就是说，承担荷载的上部结构是位于道路以下的。
第6页：下承式桥的优点
- In thethrough type(下承式)of bridge, the roadway passesbetween the elements of the superstructure. Deck structurespredominate([pri′dɔmineit]vi.占支配地位；vt.在…中占优势)，theyhave a clean appearance, provide the motorist with a betterview of the surrounding area, and are easier to widen if futuretraffic requires it.
- 因为它外形简洁，能够为汽车驾驶员提供更好的视线范围，而且如果将来由于交通要求需要拓宽道路也比较容易实现。
第7页：中长跨桥的选型原则
每一个中长跨桥梁的设计师都试图设计出一个结构可以最大程度满足那些特殊位置下的条件.以下几段的内容对桥梁一般的类型进行简要的介绍：The designer of each medium andlong-span bridge(大跨径桥)tries to devise a structure that is best suited to theconditions encountered at that particular location.The resultis an almostbewildering[bi′wildəriŋ]adj.(情况)让人困惑的,令人费解的)variety of structures that differ either in basic designprinciple or in design details.General categories of bridges are briefly described in thefollowing paragraphs
其结果往往是不同的设计师会设计出不同的结构类型，无论是就基本的设计原则还是设计细节而言。
第8页：梁桥
- Girder bridges(梁桥)Agirder[′ɡə:də]n.梁,钢桁的支架，纵梁，主梁)bridge is perhapsthe most common and most basic bridge. A log or a piece ofother material across a creek is an example of a girder bridge inits simplest form.That piece of material—called a girder orbeam—rests directly on the ground on each side or issupported on heavy foundations known aspiers([piə]n.（桥）墩,支柱).Girder bridges come in two basic varieties: plate and boxgirders. Simple or continuous beam-type bridges can be madeoftimber([′timbə]n.木材，木料，树木,横梁), steel, concrete,prestressed concrete or other materials.
- 梁桥梁桥或许是最常见和最基本的桥梁。
横跨小河的一块木头或者一根其他材料都是最简单形式的梁桥。这段材料就被称为梁——它直接搁置梁桥在水域的两侧，或者支撑在很重的基础之上也就是众所周知的柱。包括两个基本类型：板梁和箱梁。简支梁桥或者连续梁桥可以由木材、钢材、混凝土、预应力混凝土或其他材料所构成。
第9页：预应力的作用原理
- The precast, prestressed beam type is a popular bridgetype. These bridges can be found both as overpasses and asbridges. This type of bridge became popular in the 1950s.Prestress indicates that the reinforcing is stressed beforeloading, thereby placing the entire concrete beam section incompression or at a low value tension stress.Since concreteis strong in compression and relatively weak in tension, thisprocedure creates a more effective concrete section.
- 预应力就是指在荷载施加之前给予混凝土的预压力，从而使整个混凝土梁截面处于受压状态或者低拉应力状态。
因为混凝土抗压强度较高而抗拉很弱，这种操作产生了更加有效的混凝土截面。
第10页：拱桥
- Arch bridges(拱桥)Astrongpointinfavorof(赞成，支持)archbridgesintheirpleasingappearanceandaestheticelegance.Arch([ɑ:tʃ]n.拱,拱门，拱形物；vt.&vi.(使)弯成拱形)bridgescanbemadeofbricksorstoneblocksthatareheldtogetherbythecompressiveforcecharacteristicofthearch.becausetensilestrengthisnotnecessarilyrequiredforarchconstruction.Reinforcedconcreteandsteelarchesarealtogethermuchlighterstructures.Thestructureconsistsbasicallyofthearch,thedeckandusuallysomesupportsfromthearchtothedeck.
- 拱桥拱桥的优点就是造型美观优雅。
拱桥可以用砖石等块材修建，由于它们受到压力的作用而结合得很紧密。因为对于拱桥抗拉强度几乎是不需要的。钢筋混凝土拱桥和钢拱桥都是非常轻的结构类型。结构的基本组成就是拱、桥面和一些位于拱与桥面之间的支撑构件。
第11页：悬臂桥与悬索桥
- Cantilever bridges(悬臂桥)To solve the problem of increasing the span distance, otheralternatives to beam and arch bridges includedsuspension([sə′spenʃən]n.悬挂，悬浮，吊，悬架)andcantilever([′kæntili:və]n.悬臂(梁),伸臂,突梁)bridges. Among the largest cantilever bridges inthe United States is the Commodore John Barry Bridge.
- 悬臂桥为了解决持续增加的跨径问题，除了梁桥和拱桥外，可以选择的有悬臂桥和悬索桥。
在美国跨度最大的悬臂桥是Commodore John Barry桥。
第12页：悬臂桥的构造
A cantilever bridge is a bridge built using cantilevers, acantilever is a structure or beam that is unsupported at oneend but supported at the other, like diving boards. Whenanchored firmly, a cantilever is a very strong structure.Itconsists of three parts: the outer beams, the cantilevers,and the central beam. This configuration made longerspans possible and wider clearance beneath
悬臂桥是采用了悬臂结构的桥型，悬臂是一端支撑而另一端没有支撑的结构，就像跳水板。如果锚固牢固悬臂是强度很高的一种结构。它由三部分组成：边梁，悬臂，中梁。这种构造可以获得更长的跨径和更宽的净空。
第13页：悬臂桥的应用演变
- For small footbridges, the cantilevers may be simple beams;however, large cantilever bridges designed to handle road orrail traffic use trusses built from structural steel, orbox---girders(箱形梁)built from prestressed concrete.
- 对于小型人行桥，悬臂是一种简单的梁型。
- The cantilever bridge was a popular type of bridge in the firsthalf of the twentieth century, but at present, some commentatorsbelieve that thecable-stayed bridge(斜拉桥)will replace it forcomparable spanning distances.
- 在20世纪前半段时期，悬臂梁桥是一种非常普遍的桥梁形式。
但目前，一些评论家认为，斜拉桥将由于更大的跨越能力而取代悬臂桥。
第14页：悬索桥
- Suspension bridges(悬索桥)Suspension bridges are used for very long spans or for shorterspans where intermediate piers cannot be built. Of all the bridgetypes in use today, the suspension bridge allows for the longestspans.The principal structural elements of a suspension bridgeare:flexible main cables(柔性主缆),towers, anchorages,hangers, deck andstiffening([′stifn]vt.&vi.变硬，加强，加劲)girder. Some primitive examples of suspension bridges usevines([vain]n.藤本植物,藤)and ropes for cables.
- 悬索桥应用于那些无法修筑中间墩台的大跨径或稍短一些跨径的桥梁结构。
在当今使用的所有桥梁形式中，悬索桥具有最大的跨越能力。悬索桥主要的结构组成包括：柔性主缆、塔架、锚锭、吊杆、桥面板和加劲梁。一些原始的悬索桥使用藤或绳索作为缆索。
第15页：下部结构的分类
The portion of the bridge structure below the level of thebearing and above the foundation is generally referred to assubstructure. Substructure of bridge fall into two distinctcategories:end supports(端部支撑)andintermediatesupports(中间支撑).The end supports are normally described asthe “abutments”([ə′bʌtmənt]n.桥台，桥墩，桥基), whilst thegeneral term for the intermediate supports of amulti-spanbridge(多跨桥)is the “piers”.The abutments and piers areusually constructed from in situ concrete, but precast sectionscan be employed to speed up the construction process.Section B Substructure of Bridge（
桥梁的下部结构）桥梁支座以下基础以上的结构通常称其为下部结构。下部结构可以分为两个不同的类别：端部支撑和中间支撑。端部支撑通常称为桥台，而对于多跨桥的中间支撑一般称为桥墩。桥台和桥墩通常是现场混凝土浇注而成，但是预制构件的应用可以加快施工进度。
第16页：桥墩的设计
- PiersSpecial attention must often be given to the design of thebridge piers, since heavy loads may be imposed on them bycurrents, and floating ice and debris.
- 桥墩设计桥墩时必须特别注意，因为桥墩可能要承担由水流、浮冰或其他漂浮物产生的重荷。
- The general shape and features of a pier depend to a largeextent on the type, size anddimensions([di′menʃən]n.尺寸，度量，量纲)of the superstructure and also on the environment in whichthe pier is located. Piers can be solid,cellular([′seljulə]adj.多孔的，格状的),trestle[′tresl]n.支架，栈桥，高架桥orhammerhead[′hæməhed]n.倒梯形，锤头types.
- 桥墩的形状和形式在很大程度上取决于上部结构的型式、尺寸和规格以及桥墩所处的周边的环境。
桥墩可以是实心式、空心式、排架式，倒梯形。
第17页：实体桥墩与空心桥墩
- Solid and cellular piers for river bridges should be providedwithsemicircular([′semi′sə:kjulə]adj.半圆的)cut waters tofacilitate streamlined flow and to reduce scour.Other designssuch as reinforce concrete framed type have also been used.Solid piers are of masonry or mass concrete.It is permissible touse stone masonry for the exposed portions and to fill theinterior withlean concrete(素混凝土).This would save expensesonshuttering([′ʃʌtəriŋ]n.模板（壳）)and would also enhanceappearance.Cellular, trestle and hammerhead types usereinforced concrete.
- 跨河桥梁的实心桥墩或空心桥墩应当提供半削减水域，以适应水流的流向和减轻冲刷。
其它设计，如钢筋混凝土框架形式也有应用。实心桥墩一般由圬工材料或大体积混凝土构成。对于暴露在外的部分容许使用石砌圬工结构，内部填注素混凝土。这样可以减少利用模板并且外表面也得以加强。空心式、排架式和倒梯形桥墩采用钢筋混凝土。
第18页：桥墩的荷载扩散
- Vertical and horizontal loads transmitted from thesuperstructure disperse rapidly from the top of a pier. Hence,the overall design of a pier is normally conducted on a meterstrip basis, assuming auniform distribution(均匀分布)of axialand bending effects.The magnitude of the axial compressivestresses in a concrete pier is normally between 0.5~1.0N/mm2under dead loading and it is unlikely to be more than 2 N/mm2under the most severe live load conditions.The degree ofbending will depend upon the articulation of the deck and thelength of the superstructure.
- 从上部结构传递下来的垂直荷载和水平荷载在桥墩顶部迅速扩散。
因此，通常桥墩的整体设计是取单元宽度进行的，并且假定轴向力和挠度的影响都是均匀分布的。在恒载作用下，混凝土桥墩中轴向压应力的大小通常在0.5~1.0N/mm2的范围内，并且在最不利活载条件的作用下，其值一般弯曲的程度取决于桥面板的联结情况和上部结构的长度。也不会超过2N/mm2。
第19页：钢筋混凝土排架式桥墩
- Reinforced concrete framed type of piers has been usedin recent years. The main advantage in their use is due toreduced effective span lengths for girders on either side ofthe centre line of the pier leading to economy in the cost ofsuperstructure.
- 在最近几年，钢筋混凝土排架式桥墩已经普遍应用。
它的主要优势就是可以降低在桥墩中心线两侧梁的跨径，从而提高了上部结构造价的经济性。
第20页：混凝土墩柱
- Individual concrete columns are often used to supportfootbridges([′futbridʒ]n.人行桥)and bridge decks with highskew or greater height than the minimumheadroomclearance(净空高度).Columns may be vertical, inclined oreven curved in shape to produce greater aesthetic appeal. Acolumn section is normally required to resistbi-axial([bai′æksiəl]adj.双轴的，双向的)bending and significant axialloading.Concrete columns are therefore often circular orsquare, buthexagonal( [hek′sæɡənəl]adj.六角形的，六边形的)andoctagonal[ɔk′tæɡənl]adj.八边（角）形的；n.六边（角）形sections are also common.
- 单个混凝土墩柱常用来支撑人行桥和桥面板，这些桥面板斜度更大，高度也比最小净空高度高很多。
为了使结构更加美观，柱可以是垂直的、倾斜的甚至是弯曲的。柱截面通常要求可以抵抗双向弯曲和很大的轴向荷载。因此混凝土柱通常为圆形或方形，六角形和八角形截面也比较普遍。
第21页：桥台的功能
- Abutments (桥台）An abutment serves two principal functions. It is thesubstructure which supports oneterminus（[′tə:minəs]n.终点站,终点，边界,界限,极限）of the superstructure of a bridgeand, at some time, laterally supports theembankment（[im′bæŋkmənt]n.路堤，岸堤，堤）which serves as an approachto the bridge.For a river bridge, the abutment also protects theembankment from scour of the stream. Bridge abutments canbe made of masonry,plain concrete（素混凝土）or reinforcedconcrete.Hence, an abutment combines the functions of a pierand a retaining wall.
- 桥台有两个主要功能：它是下部结构，支撑桥梁上部结构的一个端部，有时它也为紧接桥梁的路堤提供横向支撑。
对于跨河桥梁，桥台还要保护路堤免受水流冲刷。桥台可以由圬工材料、素混凝土或钢筋混凝土构成。因此，桥台综合了桥墩和挡土墙的功能。
第22页：重力式桥台
One of the most common types of abutment is the gravityabutments with wing walls.It consists of a central pier supportingthe bridge seat, and two wing walls to retain the fill. All threeelements rest on a single footing.If the wing walls are at rightangles to the pier, the structure is known as a U abutment.The wing walls of a U abutment are sometimes tied togetherto reduce their tendency to overturn.角，就是众所周知的U
形桥台，其侧墙有时绑定在一起以防止结构倾覆。最常见的桥台形式是带有两个侧墙的重力式桥台。它由一个支撑桥梁支座的中心桥墩和两侧起挡土作用的侧墙组成。所有这三个部分都位于同一个基础之上。如果侧墙与桥墩呈直
第23页：敞开式与穿通式桥台
- Thespill-through(穿通式的)oropen abutment(敞开式桥台)isalso widely used. It consists of two or more vertical columnscarrying a beam that supports the bridge seat.The fill extendson its natural slope from the bottom of the beam through theopenings between the columns. In its extreme form a spill-through abutment is no more than a row of piles driven throughthe fill and supporting a bridge seat.Another common variationis a simple pier with small wings near the top. The fill in thiscase spills around the abutment.
- 穿通式或敞开式桥台的应用也比较普遍。
它是由两个或更多的支撑桥主梁的竖直柱所构成。填注材料按照其自然坡度从梁底部通过柱之间的空隙。它的极端形式穿通式桥台只是一排从填注材料中延伸出的支撑桥梁支座的桩。另外一种常见的形式就是简单的一个在顶部带有小型翼墙的桥墩，在这种情况下填注材料位于桥台周边。
第24页：桥台的设计要点
- The design of an abutment consists in assuming preliminarydimensions depending on the type of the superstructure andfoundation, and checking the stresses at thesill([sil]n.底梁，底座，基础，底面)level.The front face of the breast wall shouldhave abatter([′bætə]n.倾斜，坡度，倾斜度)of not less than 1 in25, preferably at 1 in 12.The rear batter is adjusted to get thewidth required to restrict the net pressures within theprescribed limits.
- 桥台的设计包括：根据上部结构和基础的形式拟定初步尺寸，验算地基土压应力。
胸墙前侧应该有不小于1/25的坡度，最背部的坡度要进行适当的调整，以获取所需的好是在1/12左右。宽度来限制静压力在规定的范围内。
第25页：桥台的失效模式
- A bridge abutment may fail in several ways as below, andthe final design should be checked to avoid these failures.The breast wall may fail by tensile cracks, crushing or shear.The wall maytilt([tilt]n.倾斜，车篷；vt.&vi.(使)倾斜，斜置)forward due to excessiveoverturning moment(倾覆力矩)dueto earth pressure.The wall may slide forward due to earthpressure if the vertical forces are inadequate. Though thewall may be structurally strong, failures may occur along acurved surface byrupture([′rʌptʃə]n.破裂，断裂；vt.&vi.(使)破裂)of the soil due to inadequateshear resistance(抗剪力).
- 如果垂直压力不足，在土压力的作用下墙体会产生滑移。
即使墙体强度比较高，也有可能因为土体开裂造成抗剪不足导致墙体弯曲变形而失效。桥台可能在以下几种情况下失效，而最终的设计必须保证前墙可能由于张拉裂缝、冲击或是剪切能够避免这些失效。而发生破坏。由于地震引起的过度的倾覆弯矩会造成墙体倾斜。
第26页：三峡工程主体结构
- The main structure of theThree Gorges Project(三峡工程)consists of thewater impounding dam(蓄水大坝),floodreleasing installations(泄洪设施), power plants, andnavigation facilities.The dam is a concrete gravity type with amax height of 175～185m and total 1ength of 2,500~2,800m.Thespillway([′spilwei]n.溢洪道,泄洪道)section is built in themiddle of the river channel.There are two power plants at thetoe of the dam. The navigation facilities are arranged on the leftbank.
- 在大坝底有两个电站，导航设施安排在左岸。
三峡工程的主体结构的组成包括蓄水大坝，泄洪设施，发电站，和导航设施.大坝是一个混凝土重力坝，最大高度175-180米和总长2500〜2800米，溢洪道部分建立在河道的中间
第27页：练习一 填空题
ExercisesⅠ. Fill in the blanks with the information given in the text.1. Gravity abutment consists of a central ________supporting the bridge seat, and two ________ walls to retainthe fill.2. Piers can be solid, ________, trestle or ________ types.3.Substructure of bridge fall into two distinct categories:________ supports and ___________supports.3. In some recent designs, concrete hinges have beenintroduced between the top of columns and the ________cap in order to avoid moments being transferred from deck tothe ________.pierwingcellularhammerheadendintermediatebentcolumns
第28页：桥墩与桥台的基础
- Translate the following passages from English intoChinese.Common elements of the substructure of bridge are abutments (usuallyat the bridge ends) and piers (between the abutments). Piers andabutments often rest on separately constructed foundations such asconcrete spread foundations or pile foundations, these foundations arepart of the substructure.An abutment serves two principal functions. Itsupports the end of a bridge span, and it provides at least some lateralsupport for the soil or rock on which the roadway rests immediatelyadjacent to the bridge. Hence, an abutment combines the functions of apier and a retaining wall.
- 桥梁的下部结构一般包括桥台（一般在桥两端）和桥墩（在桥台之间）。
桥墩和桥台通常建在单独施工的基础之上，基础的种类包括扩大基础和桩基础，基础是下部结构的一部分。桥台有两个主要作用，它既能支撑着桥跨结构的端部，又为衔接桥梁的路堤填土或石提供一些横向支撑力，因此桥台起着桥墩与挡土墙共同所起的作用。
第29页：翼墙与胸墙基础
- For typical forms of reinforced concrete abutments, thewing walls have been cantilevered without extending the baseof breast wall for support, as would have been necessary formasonry abutment.The slope of the bottom edge of the wingshould be such as to have this edge below the level of therevetment of the embankment.
- 对于典型的钢筋混凝土桥台，由于没有延伸胸墙基础来做支撑，翼墙处于悬臂状态，这一点对圬工桥台是很有必要的。
翼墙底面边缘设置斜坡的目的是使这个底边低于路堤的挡土墙的底面。
第30页：墩身顶部尺寸的确定
- The dimensions of the top of a pier shaft for a bridge aredetermined by practical considerations such as the magnitudeof the bridge-shoe reactions, the distance required to providefor expansion of the superstructure, and the distance betweentrusses or girders.If the shaft extends through a body of water,its shape may be streamlined below high water to preventeddy currents and scour.
- 桥梁墩身顶部的尺寸取决于实际条件，如桥梁支座反力的严重程度、需要提供扩大的上部结构的距离，以及桁架或梁之间的距离。
如果墩身延伸时通过水体，它的形状有可能由水位决定，以防止涡流和冲刷。
