土木工程桥梁方向毕业设计外文及翻译

1、毕业设计（论文）资料附件:外文文献原文及译文t=r.号:级:学生姓名: 学 班专业:十木工程（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. transpor

2、tation 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, tr

3、affic 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 U.S.institute of transportation engineers are complete than, the British institut

4、ing 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: t

5、he 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,650,000.fifty

6、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:19556,466,00019609,439,000196512,938,000197014,950,000197417,247,000In order to see the problem in every day terms ,consider high stree

7、t. 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 thesame standard as today, the road might need to be wid

8、ened 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 dif

9、ferent countries are obviously at different stagesin 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 moment

10、um 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:India0.01 cars/personIsrael0.05cars/perso

11、nJapan0.09 cars/personIreland0.13 cars/personNetherlands0.20 cars/personGreat Britain0.21 cars/personWest Germany0.23 cars/personAustralia0.31 cars/personUSA0.44 cars/personin vehicle ownership is only part of the overall trafficBut the growth problem. obviously,if a country has unlimited roads of e

12、xtreme 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

13、 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

14、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 mode

15、rn 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 parkin

16、g 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

17、 still to some extent a status symbol, a symbol of prestige.every family wants to own one, and takes steps saving or borrowing-to get one. as incomes and standards rise the second car becomes the target. any move to restrict the acquisition of the private car would be most unpopular-and politically

18、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 time-i.e. particularly the journey to work it may be less

19、 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 facilitie

20、s 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 o

21、rder 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

22、 U.S. 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 beenconstructed in the United States. Railroad bridges utilizing prastressedconcrete have b

23、ecome 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 (13.7m).It should be understood that this is an arbitrary figure, and there is no definite line of de

24、marcation 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 whe

25、n used on very short spans. The slabs can be made in any convenient width,but widths of 3 or 4 ft (0.9 to 1.2m) have been common.Keys 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,

26、 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 (0.9 to 1.2 m) wide with thicknesses from 18 to 27 in (45.7 to 68.6cm). Precast hollow slabs can be made

27、 in any convenient width and depth, and frequently are used in bridges having spans from 20 to 50 ft (6.1 to 15.2m). 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 c

28、oncrete topping an accecptable appearance and levelness.Transverse reinforcement normally is provided in precast concrete bridge superstructuresfor the purpose of tying the structure together in the transverse direction. Well-designed ties ensure that the individual longitudinal membersformingthe su

29、perstructure 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 t

30、he bars. In some instances,the transverse ties consist of post tensioned tendons 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

31、 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 re

32、inforcement, 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

33、 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 r

34、equires 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 precastslab types of construction, unless precast slabs are used to span between the stringers in

35、 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 be

36、en 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 prestressedconcrete are defined as being from 45 to 80 ft (13.7 to 24.4m). Prestressed concrete bridges in this span ran

37、ge 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

38、 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 composit

39、e, 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 (1.5 to 1.8m). The cast-in-place deck is generally from 6.0 to 8.0 in(15.2 to 20.3cm) in thickness. This type of framing is very much the same as

40、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

41、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 sect ion. Average con struct ion dep ths are requires when stringers with large flanges are used in composite co

42、nstruction, 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 constru

43、ction , 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

44、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 onl

45、y 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 span

46、s 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, wh

47、ich 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 segmenta

48、l 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 sp

49、ans 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 i

50、n 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。虽然如 此交通工程已经部分计划 .可是，训练不同义。 计划的运输涉及计划， 功能的 设计，为运输的任何方式熟练的经营管理， 为了为人和货物的安全，迅速， 舒适，方便，节约和环境运动作准备。在那宽的范围内， 交通工程关于道 路，道路网络，端子点，关于土地和他们的有运输的其他方式的关系处

51、理那 些功能。那些定义，那些定义， 基于那些美国研究院的 1976 个工程师完整 的运输比较英国土木工程的设立， 处理计划的交通和道路的设计， 空地发 展和停放设备并且与一起要提供安全， 方便和节约运动的车辆和行人的掌握 的交通。那些训练的定义变得清楚：那些方法学连续发展并且变得越来越科 学。早的经验法则技术正消失。交通问题这些纪律不成熟： 存在着很大的问题并且仍然增长。 在 1920 辆机动车的 总数，在英国批准是 650，000.50 年以后那些可比较数字在 14，950， 000 一增长系数的 23 倍.在近年成长率已经有点减弱，但是这仍然是相当多的19556,466,00019609,

52、439,000196512,938,000197014,950,000197417,247,000为了看见在每天条件的问题，考虑高速公路。如果提出趋势，继续， 预 计在交通在这道路上的如此的今后 15 年内将以百分之 40 的大约增加到百 分之 50 .如果交通的这被增加的卷是成为在与今天相同的标准的计量， 行人 穿过，道路可能通过相似的百分之 40 到 50 或许交通的额外的小路需要加 宽。 在人情况里， 接受可预知的将来的需求将破坏整个都市的环境的性格,并且显然不可接受。交通问题具有世界范围关心， 但是不同的国家显而易 见在在交通与逐步上升的遥遥领先美国里的不同的阶段， 当一个县有很少 道

53、路和相对低的问题时， 那些国家一被打开以道路系统，那些生活水平和 那些需求就适合电动机运输都上升 ,迅速抽打冲力 .最终和舞台对这发生哪 个易受到相当多辩论需求适合变得满足的小汽车，公共汽车和运货汽车。 . 这一阶段被称为饱和阶段。对比较来说，汽车所有权把不同国家计算进去在 1970 年印度0.01 辆/人以色列0.05辆/人日本0.09辆/人爱尔兰0.13辆/人荷兰0.20辆/人英国0.21辆/人西德0.23辆/人澳大利亚0.31辆/人美国0.44辆/人但是在车辆所有权方面的发展只是总的交通问题的一部分 .显而易见，如 果一个国家有极端的宽度无限的道路，交通问题将不上升。世界上的没有国 家能

54、满足这要求：除其它任何事情外，不将适合每辆车辆使用道路做经济。 这个数字正稳定地减少。3 个可能的解决办法基本问题的交通因此简单一不断增加车辆的数量想办法使用太少道路空间。解决的方法问题其他一不也困难选择从 3 可能性：建造，应付需求的足够的大小的足够的道路。通过限制批准的车辆的数量限制对道路的需求。在(A)和(b)之间的妥协建造一些额外的道路，使用和那些已经存在的道路网络兑一他们的全部潜能， 并且同时使用一些抑制测量，限制，尽可能 需求增加。汽车仍没有需求的可见的结局可以看见， 以及 216 由于在英国在大楼道路的 每公里费用 100 万英镑左右范围应付一个无限制的需求的现代使道路的费用 将

55、太大。增加这项费用，如此狭小，喧嚣的岛一样的使用空间不能被认真地 考虑。.在洛杉矶，城市在那些停车空地到处建造适合，那些汽车。我们的城 市已经被基本上建造， 没有人将考虑通过在汽车周围使他们虚弱和再造毁坏 他们的性格， 因此第一个可能的解决办法就是规章。即使今天， 在一个至少半富裕的时代在大多数西方的世界里， 然在某种程度上是身份象征，一个威望的象征。每家庭想要拥有一辆车，并 且采取措施救或者借得到一辆。当收入和标准上涨时，二手车成为目标。限 制获得私人汽车的任何行动将是非常不受欢迎的和在政治上不太可能。很多目的个人运输理想，它使用可能接受的买得起挨门挨户的私人汽车 观念的灵活性。很多目的个人

56、运输理想，它使用可能适应的买得起挨门挨户 的私人汽车观念的灵活性 .那些群众，运动的人以来沿着具体走廊在有限时期 内即. 特别要设法安排的那些旅行可能被较少容易容纳。 其他运输方式可能更 有效率。有点妥协解决办法是不可避免 基本的交通问题的答案。这是执行 这个妥协解决办法那，交通工程得到它所应得。交通工程保证任何新设备没 被过于屈尊正确地位于满足需求。它保证现有的设备被完全使用，以非常有 效率的方式。 . 那些履行的这些职责需要那些选择需求的调节可能： 在那些山 峰时期内使那些使用的那些不那么有吸引力的汽车， 为了公共运输可能更 有效地使用有限的道路空间。这样的抑制措施经常伴随着在公开传送服务方面的改进，以便接受对他 们的额外的需求。预应力混凝土桥梁预应力混凝土自 20 世纪 90 年代末期首次在欧洲发明以来，被广泛应用 于美国桥梁的建设。在美国，上千的公路桥梁建设中使用了后张预制预应力 混凝土和现浇混凝土。而且，预应力混凝土在铁路桥梁中的应用也变的非常 普及。并且，近些年来预应力混凝土桥梁在不断的应用和改进。短跨径桥梁：跨径小于 13.7m 的桥梁，称为短跨径