桥梁专业毕设文献翻译

1、精选优质文档-倾情为你奉上 毕业设计(文献翻译)译文及原文复印件学生姓名： 左烨 学 号： 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

2、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型梁因其截面类似于数学符号而得名，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。

3、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。因此,在大多数情况下,所有梁桁架桥是直的。桁架梁是由很多小桁架组成，支撑大量的重量，跨越较大的距离。在大多数情况下,设计、制造和安装桁架是相对简单的。然

4、而，一旦组装的桁架占用较大的空间，以复杂的结构形成，就会分散司机的注意力。像梁桥一样，既有简单的桁架桥，又有连续桁架桥。桁架桥的各个部件体积小，使其成为在大型部件或部分部件不能装运或者大型起重机械和重型设备不能使用的地方处理想的桥梁型式。由于桁架是一个空洞的骨架结构，道路可能越过（见插图2）甚至通过（见插图1），同时考虑到桥下的清场，这是其他桥型不能比的。桁架也按基本设计使用来分类。最具代表性的包括华伦桁架，普拉特桁架以及豪威桁架。华伦桁架也许是包括简单或是连续桁架中最常见的型式。对于跨度较小的，无垂直桁架可以给结构一个简单的外观（见插图1）。对于跨度较大的桁架桥，垂直桁架可以提供额外的力（见

5、插图2）。华伦结构跨度通常为50100米。普拉特桁架因其对角线桁架组成除了两边均向跨度中心倾斜而得名。除了靠近中心的对角线桁架，其他所有的桁架只有在垂直短桁架受压力时受到斜拉力。这就使得可以用较为稀薄的桁架构成使得设计更为经济。豪威桁架（见插图4）是普拉特桁架相反的结构。对角线桁架朝向相反方向并承担压力。这对于钢桥来说是非常不经济的，因此它的使用也是很少见的。刚架桥刚构桥梁有时也被称为框架结构的桥梁。在标准的梁桥中，主梁和桥墩是分开的结构。然而刚构桥中主梁和桥墩是一个整体。刚构桥的横截面通常是I型或是箱型。连续刚构桥的设计计算比简支梁桥复杂。桥墩和主梁的连接处制作困难，需要计算准确且注重细节。

6、尽管有许多可能的理论形状，但是近些年来使用的结构形式只有型，斜腿形和V字型框架。斜腿刚构桥特别适合于跨越河流山谷，因为倾斜一定角度的桥墩可以有效的跨越障碍而不需在河流中央修建基础或在山谷中修建桥墩（见插图1）。V型刚构桥可以有效地利用基础。每个V字型墩提供两个支撑梁的力，同时减少基础的数量，从而使得外形更加简单。（见插图3）型刚构结构通常用于内城高速公路的桥墩或是支撑。该框架支撑起高出的公路，同时允许车辆从桥下直接通过。（见插图2）拱桥在梁桥之后，拱桥是第二古老的桥式和经典结构。不像简支梁桥，拱桥非常适合用石材建造。许多古老知名的拱桥时至今日仍然伫立着。穿越山谷与河流拱桥是个很好的选择，因为拱

7、桥在中间部分不需要桥墩支撑。拱桥可以成为更美桥型之一。拱桥使用曲拱结构，提供一个高抗弯力。不像梁桥和桁架桥，拱桥的两端固定在同一水平方向上（即不允许水平方向运动存在于轴之中）。因此当负载在桥上（如一辆车通过时）水平力就会在拱的轴承中产生。这些水平力对于拱桥来说是独特的，因此拱桥只能应用于地面基础牢固稳定的地方。就像桁架桥一样，道路可能越过（见插图1）或者通过拱（见插图4）或者在某种情况下，两者都有（见插图3）。结构上拱桥有四种基本结构形式：无铰拱，双铰拱，三铰拱和系杆拱桥。无铰拱（见插图1）没有铰并且不允许基础的转动。因此基础会承受大量的荷载（水平，垂直，弯曲力），因此无铰拱只能在地面基础十分

8、稳定的情况下修建。然而，无铰拱是一种非常僵硬的结构比其他拱产生的挠度也就相对少了。两铰拱（见插图2）使用了允许转动的铰接轴承。在轴承中只产生水平和垂直力。这或许是最常用的钢拱的更改，通常也是一个经济的设计方式。三铰拱（见插图3）增加了一个铰链在拱的顶部。三铰拱因基础运动（地震，下沉等）受到的影响较小。然而，三铰拱会遭受等多的挠度影响，铰链很复杂，难以制作。因此三铰拱很少使用。系杆拱桥（见插图4）是一种组合式拱桥，允许在地面不够稳固以抵抗水平力的变化的情况下建造。连接拱的两端和本身而不是依赖基础来承受水平力，因此称之为系杆拱桥。斜拉桥一座典型的斜拉桥（见插图1和2）是与一个或多个塔柱连续梁跨度中

9、间桥墩的架设。缆绳从这些塔柱上拉下（通常向两边）来支撑主梁。钢缆绳非常强韧有弹性。钢缆绳非常经济，且可以形成细长结构但仍然能跨越较远距离。尽管少数的缆绳强度就足以支撑整个桥，他们的弹性使得缆绳很难承受我们很难考虑到得力：风力。对于跨度较大的斜拉桥，必须做出仔细研究来确保缆绳和桥梁在风力作用下的稳定情况。桥的重量越轻，对于风力的抵抗能力越弱，但是对于抵抗地震却是有利的。但是，地震或是时间推移下地基的不均匀沉降会使斜拉桥产生破坏，因此必须认真规划基础。斜拉桥即现代又简洁的外观，使之成为有吸引力独特的地标。缆绳的独特属性以及其作为一个整体结构，使得斜拉桥的设计十分复杂。较大跨度的斜拉桥，风力和温度的

10、影响必须考虑，这个计算是非常复杂的，不得不借助计算机和计算机分析。斜拉桥桥索的制作也比较困难。桥索的布线和主塔的附件构造复杂，需要精密制造。斜拉桥没有明显的分类。但是，它可以根据跨越数，塔柱数，主梁类型和缆绳数量区分。塔柱的数量和类型有很多变化，缆绳的数目和排列也有变化。典型的主塔形式有：单柱、双柱、门形或是A型（见插图2和3）。桥索的排列也不尽相同。典型的型式有单面、扇形、竖琴型、星型（见插图4）。在某些情况下，桥索只有在塔柱的一侧安装在梁上，另一侧被锚固在基础上或用以其他力来平衡。悬索桥现如今使用的所有桥型中，悬索桥是跨越距离最长的桥型。乍一看,这和悬浮的斜拉桥可能看起来很相似,但他们有很

11、大的不同。虽然大跨度悬索桥现如今技术领先,但他们其实是一种很古老的形式的桥。一些最原始的悬索桥的例子是使用藤蔓和绳子作为缆索。金属的发展带来了铁棍和锁链的使用。但是知道钢丝索的引进才使得跨越500米以上成为现实。今天明石海峡大桥拥有世界最长的1991米的跨度。典型的悬索桥是与一个或多个桥塔通过缆绳与主梁在桥墩中央相连。主梁本身在较短的跨度下是桁架或是箱梁，板梁并不少见。桥的两端通过放置大型锚固设备或是重物用以固定缆绳。主缆延伸从一个锚锭越过塔顶连接到另一个锚锭处。这种跨越结构的缆绳称之为马鞍（检查图2）。马鞍型允许缆绳从一边到另一边顺利地传递荷载。从主缆悬挂下来的像挂钩一样的小缆绳悬挂下来连接

12、在主梁上。有些悬索桥不适用锚锭，缆绳直接连接主梁的两端。依靠这些自锚悬索桥跨度的重量,以平衡中心跨度和锚定缆绳。因此，不同于普通桥梁依靠墩台承重，悬索桥主梁或是桥面板实际上是悬挂在主索上。桥的大部分重量和车辆荷载都被缆索承担。反过来，缆绳由主塔支撑，因此主塔就必须支撑大量的重量。正如以上解释的斜拉大桥钢缆索强度极强,然而灵活。就像一个很强韧的绳子,那将是很好的为悬挂或拉一些事的选择,但是试图推动物体是没有用的。大跨度悬索桥尽管在普通交通荷载下很强韧，极易受到风荷载的作用。必须采取特殊的措施以确保大桥在强风下不晃动或是振动。最著名的空气动力不稳定的大桥的例子是美国华盛顿州的塔科玛湾海峡大桥。这篇

13、英国布里斯托尔大学对于塔科玛湾海峡大桥灾难的优秀的网页照片和短片会解释为什么空气动力稳定性如此重要。BridgesGirder BridgeA girder bridge is perhaps the most common and most basic bridge. A log across a creek is an example of a girder bridge in its simplest form. In modern steel girder bridges, the two most common girders are I-beam girders and box-g

14、irders.If we look at the cross section of an I-beam girder we can immediately understand why it is called an Ibeam (illustration #1.) The cross section of the girder takes the shape of the capital letter I. The vertical plate in the middle is known as the web, and the top and bottom plates are refer

15、red to as flanges. To explain why the I shape is an efficient shape for a girder is a long and difficult task so we won't attempt that here. A box girder is much the same as an I-beam girder except that, obviously, it takes the shape of a box. The typical box girder has two webs and two flanges

16、(illustration #2.)However, in some cases there are more than two webs, creating a multiple chamber box girder.Other examples of simple girders include pi girders, named for their likeness to the mathematical symbol for pi, and T shaped girders. Since the majority of girder bridges these days are bui

17、lt with box or I-beam girders we will skip the specifics of these rarer cases.Now that we know the basic physical differences between box girders and I-beam girders, let's look at the advantages and disadvantages of each. An I-beam is very simple to design and build and works very well in most c

18、ases. However, if the bridge contains any curves, the beams become subject to twisting forces, also known as torque. The added second web in a box girder adds stability and increases resistance to twisting forces. This makes the box girder the ideal choice for bridges with any significant curve in t

19、hem.Box girders, being more stable are also able to span greater distances and are often used for longer spans, where I-beams would not be sufficiently strong or stable. However, the design and fabrication of box girders is more difficult than that of I beams. For example, in order to weld the insid

20、e seams of a box girder, a human or welding robot must be able to operate inside the box girder. TrussThe truss is a simple skeletal structure. In design theory, the individual members of a simple truss are only subject to tension and compression forces and not bending forces.Thus, for the most part

21、, all beams in a truss bridge are straight. Trusses are comprised of many small beams that together can support a large amount of weight and span great distances. In most cases the design, fabrication, and erection of trusses is relatively simple. However, once assembled trusses take up a greater am

22、ount of space and, in more complex structures, can serve as a distraction to drivers.Like the girder bridges, there are both simple and continuous trusses. The small size of individual parts of a truss make it the ideal bridge for places where large parts or sections cannot be shipped or where large

23、 cranes and heavy equipment cannot be used during erection. Because the truss is a hollow skeletal structure, the roadway may pass over (illustration #2) or even through (illustration #1) the structure allowing for clearance below the bridge often not possible with other bridge types.Trusses are als

24、o classified by the basic design used. The most representative trusses are the Warren truss, the Pratt truss, and the Howe truss. The Warren truss is perhaps the most common truss for both simple and continuous trusses. For smaller spans, no vertical members are used lending the structure a simple l

25、ook (illustration #1.) For longer spans vertical members are added providing extra strength (illustration #2.) Warren trusses are typically used in spans of between 50-100m.The Pratt truss (illustration #3) is identified by its diagonal members which, except for the very end ones, all slant down and

26、 in toward the center of the span. Except for those diagonal members near the center, all the diagonal members are subject to tension forces only while the shorter vertical members handle the compressive forces. This allows for thinner diagonal members resulting in a more economic design.The Howe tr

27、uss (illustration #4) is the opposite of the Pratt truss. The diagonal members face in the opposite direction and handle compressive forces. This makes it very uneconomic design for steel bridges and its use is rarely seen.Rigid FrameRigid frame bridges are sometimes also known as Rahmen bridges. In

28、 a standard girder bridge, the girder and the piers are separate structures. However, a rigid frame bridge is one in which the piers and girder are one solid structure.The cross sections of the beams in a rigid frame bridge are usually I shaped or box shaped. Design calculations for rigid frame brid

29、ges are more difficult than those of simple girder bridges. The junction of the pier and the girder can be difficult to fabricate and requires accuracy and attention to detail.Though there are many possible shapes, the styles used almost exclusively these days are the pi-shaped frame, the batter pos

30、t frame, and the V shaped frame.The batter post rigid frame bridge is particularly well suited for river and valley crossings because piers tilted at an angle can straddle the crossing more effectively without requiring the construction of foundations in the middle of the river or piers in deep part

31、s of a valley (illustration #1).V shaped frames make effective use of foundations. Each V-shaped pier provides two supports to the girder, reducing the number of foundations and creating a less cluttered profile (illustration #3.)Pi shaped rigid frame structures are used frequently as the piers and

32、supports for inner city highways. The frame supports the raised highway and at the same time allows traffic to run directly under the bridge (illustration #2.)ArchAfter girders, arches are the second oldest bridge type and a classic structure. Unlike simple girder bridges, arches are well suited to

33、the use of stone. Many ancient and well know examples of stone arches still stand to this day. Arches are good choices for crossing valleys and rivers since the arch doesn't require piers in the center. Arches can be one of the more beautiful bridge types.Arches use a curved structure which prov

34、ides a high resistance to bending forces. Unlike girder and truss bridges, both ends of an arch are fixed in the horizontal direction (i.e. no horizontal movement is allowed in the bearing). Thus when a load is placed on the bridge (e.g. a car passes over it) horizontal forces occur in the bearings

35、of the arch. These horizontal forces are unique to the arch and as a result arches can only be used where the ground or foundation is solid and stableLike the truss, the roadway may pass over (illustration #1) or through an arch (illustration #4) or in some cases both (illustration #3.) Structurally

36、 there are four basic arch types: hinge-less, two-hinged, three hinged and tied arches.The hinge-less arch (illustration #1) uses no hinges and allows no rotation at the foundations. As a result a great deal of force is generated at the foundation (horizontal, vertical, and bending forces) and the h

37、inge-less arch can only be built where the ground is very stable. However, the hinge-less arch is a very stiff structure and suffers less deflection than other arches.The two hinged arch (illustration #2) uses hinged bearings which allow rotation. The only forces generated at the bearings are horizo

38、ntal and vertical forces. This is perhaps the most commonly used variation for steel arches and is generally a very economical design.The three-hinged arch (illustration #3) adds an additional hinge at the top or crown of the arch. The three-hinged arch suffers very little if there is movement in ei

39、ther foundation (due to earthquakes, sinking, etc.) However, the three-hinged arch experiences much more deflection and the hinges are complex and can be difficult to fabricate. The three-hinged arch is rarely used anymore.The tied arch (illustration #4) is a variation on the arch which allows const

40、ruction even if the ground is not solid enough to deal with the horizontal forces. Rather than relying on the foundation to restrain the horizontal forces, the girder itself "ties" both ends of the arch together, thus the name "tied arch."Cable StayedA typical cable stayed bridge

41、 (illustration #1 & 2) is a continuous girder with one or more towers erected above piers in the middle of the span. From these towers, cables stretch down diagonally (usually to both sides) and support the girder.Steel cables are extremely strong but very flexible. Cables are very economical as

42、 they allow a slender and lighter structure which is still able to span great distances. Though only a few cables are strong enough to support the entire bridge, their flexibility makes them weak to a force we rarely consider: the wind.For longer span cable-stayed bridges, careful studies must be ma

43、de to guarantee the stability of the cables and the bridge in the wind.The lighter weight of the bridge, though a disadvantage in a heavy wind, is an advantage during an earthquake. However, should uneven settling of the foundations occur during an earthquake or over time, the cable-stayed bridge ca

44、n suffer damage so care must be taken in planning the foundations. The modern yet simple appearance of the cable-stayed bridge makes it an attractive and distinct landmark.The unique properties of cables, and the structure as a whole, make the design of the bridge a very complex task. For longer spa

45、ns where winds and temperatures must be considered, the calculations are extremely complex and would be virtually impossible without the aid of computers and computer analysis. The fabrication of cable stay bridges is also relatively difficult. The cable routing and attachments for the girders and t

46、owers are complex structures requiring precision fabrication.There are no distinct classifications for cable-stayed bridges. However, they can distinguished by the number of spans, number of towers, girder type, number of cables, etc. There are many variations in the number and type of towers, as we

47、ll as the number and arrangement of cables. Typical towers used are single, double, portal, or even A-shaped towers (illustration #2 & 3.)Cable arrangements also vary greatly. Some typical varieties are mono, harp, fan, and star arrangements (illustration #4.) In some cases, only the cables on o

48、ne side of the tower are attached to the girder, the other side being anchored to a foundation or other counterweight.SuspensionOf all the bridge types in use today, the suspension bridge allows for the longest spans. At first glance the suspension and cable-stayed bridges may look similar, but they

49、 are quite different. Though suspension bridges are leading long span technology today, they are in fact a very old form of bridge. Some primitive examples of suspension bridges use vines and ropes for cables.The development of metals brought the use of linked iron bars and chains. But it was the in

50、troduction of steel wire ropes that allowed spans of over 500m to become a reality. Today the Akashi Kaikyo bridge boasts the world's longest center span of any bridge at 1,991 meters.A typical suspension bridge (illustration #1) is a continuous girder with one or more towers erected above piers

51、 in the middle of the span. The girder itself it usually a truss or box girder though in shorter spans, plate girders are not uncommon. At both ends of the bridge large anchors or counter weights are placed to hold the ends of the cables.The main cables are stretched from one anchor over the tops of the tower(s) and at