桥梁设计存在的主要问题中英文翻译.doc

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1、道路桥梁与渡河工程专业英语Road Bridge and River-Crossing EngineeringSpecialized English学 院：土木工程班 级：道桥09-01班姓 名：*学 号：090580136日 期：2011-11-4THE MAIN PROBLEMS OFDOMESTIC BRIDGE DESIGNINGNow, the countrys structural design process, such tendencies: more intensity considered in the design and durability consider less

2、 attention intensity limit to the use of state without limit state, and throughout the life cycle of the most important when it is precisely the use of performance; attention to the construction of the structure without attention to the maintenance of the structure. In fact, the current design of th

3、e bridge for more durability is a concern, as a concept, did not explicitly put forward the request of the use of life, nor the durability of specialized design. These tendencies to a certain extent, led to the current project accidents, the use of poor performance, the short life of the adverse con

4、sequences of structural engineering with the increasing emphasis on international durability, safety, contrary to the trend of applicability; does not conform to the structure dynamic and comprehensive economy requirements.Bridge safety, durability, the main reason for poor 1) Construction and manag

5、ement of low level More bridges at home and abroad destruction and the sudden collapse of the bridge has been engineering more concerned about security issues. The general view is that the current project is barbaric incident management and construction caused by corruption. For the short term, such

6、 as the destruction and collapse of a sudden, mostly because of construction quality did not meet specifications and design requirements, typical problems include inadequate and construction materials intensity of failure; also exist, such as individual bridge jerry serious management issues, but al

7、so on bridge safety of the fatal damage.And a large number of bridges in the far did not achieve the expected life time, there has been affecting the normal use of disease and deterioration, especially in a number of bridges in use only a few years, or even just completed soon on the serious problem

8、 of insufficient durability, which and the low quality of construction is an important relationship, the typical problems of inadequate protection of reinforced and the current widespread in the construction site of the serious problem of cracking component. These construction, although short-term d

9、eficiencies of the bridge will not be the normal use of a clear impact, but the long-term durability of the structure will have a very negative hazards.2) Design theory and structure of the system is not perfect enoughWhile acknowledging the existence of the problem, but it also, it is undeniable th

10、at bridge design fields, in particular on the bridge construction and use of the issue of safety there is still much improvement. Structural design first and foremost task is the choice of reasonable economic programmer, followed by the structural analysis and design of components and connections, a

11、nd access to regulate the safety factor specified or reliability of indicators to ensure the safety of the structure.Many designers often complacent with norms on the structural strength of the safety of the need, and ignore the structural system, structure, structure, structure of materials, struct

12、ure maintenance, as well as from the structural durability of the design and construction process to make use of that often appear in the man-made wrong areas to strengthen and guarantee the safety of the structure. Some structural integrity and ductility inadequate redundancy small, but some of Sch

13、ema and the uncertainty of the line, causing partial excessive force; some concrete strength grade too low to protect slice through small diameter steel micromanage , a thin cross-section components of these structures have weakened the durability, it would seriously affect the safety of the structu

14、re. Many bridges, although the design specifications meet the requirements of the strength of only 5 to 10 years because of the durability of the problems affecting structural safety. Structural Durability shortage has become one of the most realistic security issues, from design to construction and

15、 materials, such as angle of measures to strengthen the durability of the structure.Of the environment and the use of different conditions, different design of the structural system will target different aspects of the layout and structure requirements. Norms can not cover in detail the design staff

16、 should solve the various problems in the updated norms faster can also adapt to new understanding, new technologies, new materials, rapid development of the structure of the new requirements. Therefore, reasonable and reliable addition to the structures is designed to meet the requirements of norms

17、, and to design a structure to the correct understanding of nature, rich experience and accurate judgments.And the need to improve efforts in the direction 1) Should pay more attention to the durability of structural problemsBridge in the construction and use of the process, will be subject to envir

18、onmental, and the erosion of harmful chemical substances, and to bear vehicles, wind, earthquake, fatigue, overloading, human factors, such as external role, and bridge materials used by the self-degradation of performance will continue , resulting in the structure of the different degrees of damage

19、 and deterioration. In the field of long-span bridges, and from the country since the 1980s, the construction of a large number of cable-stayed bridge, although so far there collapse or serious damage to the few examples, but has more bridges because of the durability of cable to the problem advance

20、 for cable, and this not only affects the use of increased economic losses.Needs to be pointed out is that many of these problems and did not conduct a reasonable durability of the design, which has also prompted renewed awareness of durability of the bridge. Diseases are a lot of examples of that,

21、in addition to construction materials and the reasons for a decisive impact on the durability of the structure from the structural factors (is design) flaws. From the country in the 1990s started to attach importance to the durability of the structure of the study, has also made quite a few successe

22、s. Most of these studies and statistics from the analysis of the material point of view, on how to structure and design from the perspective of how and the design and construction staff to be readily accepted and operation of the bridge approach to improving the durability has been little research.

23、Moreover, for a long time, people have always been emphasis on the methods of calculation on the structure; it ignores the details of the overall structure and processing concern. Design and durability of the structure of the structural design of a conventional nature of the difference between the c

24、urrent efforts will be needed on the durability of the qualitative analysis to the quantitative analysis of development.2) Emphasis on the study of fatigue damageBridge structure to withstand the vehicle load and wind load are dynamic load will be in a cycle of change within the structure of the str

25、ess, not only will cause the vibration of the structure, but also from the structure of the accumulated fatigue damage. The bridge is not used by the material is uniform and continuous, in fact there are many tiny flaws in the role of cyclic loading, these deficiencies will be progressive developmen

26、t of micro, a merger of injury, and gradually formed in the material macro cracks. If the crack is not effective macro-control, is very likely to cause material, the structure of brittle fracture. Early fatigue damage is not always easy to be detected, but the consequences are often disastrous.Fatig

27、ue damage has been considered in the design of steel bridge is the core issue of fatigue caused by the steel structure of steel crack more cases, many caused by fatigue fracture bridge collapse example. Over the past 20 years, fatigue injury research has entered the concrete structure, but by the us

28、e of corrosion of reinforced concrete structures dynamic performance and fatigue properties of need to be strengthened. On the fatigue damage of not only refers to the entire structure, the bridge structure often as a matter of fact some of the key parts of local fatigue failure of the entire struct

29、ure and lead to failure, such as the cable-stayed bridge cables anchoring end of the fatigue damage.3) Pay full attention to the problem of overloading the bridgeThere are three main vehicle overloading: One is the early construction of the old bridge overage load carriers and the other is the passa

30、ge of vehicular traffic bridge over the original design; the other is illegal overloading of vehicles. The first two are the main reasons for the changes in the design load and the increase in the volume of traffic; users of the latter are illegal overloading of vehicles operating, the latter two ph

31、enomena of overloading in road transport in China is more common.On the one hand, overloading the bridge may trigger fatigue. Overloading bridge would increase the rate of fatigue stress injury aggravated, or even some structural damage caused by overloading accidents. On the other hand, due to over

32、loading of the bridge caused internal damage can not be restored, the bridge will be made of the work under normal load conditions change, which could endanger the safety of bridges and durability. For example, the concrete bridge has always been regarded as an adequate durability, but the overloadi

33、ng of the vehicle, cracking may occur; cracks even in the load will be able to divest closed, but the internal structure of concrete has been damage, cracking component from the lower bend, Stiffness decline was in the normal use of load, should not have been cracking or structural cracks have becom

34、e smaller cracks in excess of the norms to allow a larger cracks or deformation. These will be used for structural performance and long-term durability has a negative impact, in addition to the Traffic Control departments should strengthen management, but also the need for overloading the consequenc

35、es of research, analysis.4) Actively learn from foreign experience and results Domestic bridge design the main problems is the use of the normal structure of poor performance (referring compared with the design expectations can be attributed to poor performance of the application, including the brid

36、ge too much vibration, linear irregularity, joints, diarrhea, excessive structural cracking and deformation, etc.), durability and safety of the poor (including short life span, high maintenance costs, and more frequent accidents, etc.). While these issues have with the current domestic construction

37、 quality and management level lower, but to be fair, since this situation can not be resolved in the short term, then as engineers we should address this issue in the premise, are fully taken into account stage of construction and management and materials technology, the use of appropriate security,

38、 the appropriate way to ensure that the design of a bridge to the use of the performance, this is a more proactive and effective means. Especially the durability of the bridge and safety of many problems with the structure or the use of material selection are unreasonable and improper handling of th

39、e structural details.In European countries (such as Germany, Denmark, etc.), attached great importance to the structure of a performance-based design (PBD, Performance Based Design), which includes structural deformation, cracks, vibration, strong, handsome, durability, fatigue and so on. PBD study

40、is to enable operators in the structure of the process, in addition to the guaranteed minimum security requirements; the idea of the use of performance should be good (including life and durability, corrosion resistance, fatigue resistance, aesthetics, etc.). By their very nature, the European count

41、ries PBD theory, research in the use of structure in the course of performance out of service, the performance by the weakening of the reasons for its occurrence and the mechanism of the law, to seek a new structural design concepts and methods.From the point of view of Europeans, PBD seems to be to

42、 the durability of the structure at the core of the comprehensive use of performance indicators to consider. This is the domestic engineering should be based on the Enlightenment. At present the domestic design can be seen as static design, built only at the design definition of a structures ability

43、 and performance, and during the performance of operating time and the actual deterioration of the performance of the lack of sufficient awareness and consideration; In other words, the economic point of view is to consider only the construction cost, the expense of operating and maintenance costs a

44、nd service life should be the relative cost-effectiveness.Bridge safety and durability shortage has become an urgent need to address the problem, we should actively learn from successful foreign experiences and practices, in addition to strengthening the construction quality management, bridge desig

45、n concepts and from the structure and tectonic perspective to the design of durability. At the same time need to study fatigue and overloading the durability of the bridge structure effects.国内桥梁设计存在的主要问题现在，国内的构造设计过程中，有这样的倾向：设计中考虑强度多而考虑耐久性少；重视强度极限状态而不重视使用极限状态，而构造在整个生命周期中最重要的却恰恰是使用时的性能表现；重视构造的建造而不重视构造

46、的维护。实际上，目前的桥梁设计中，对于耐久性更多的只是作为一种概念受到关注，既没有明确提出使用年限的要求，也没有进展专门的耐久性设计。这些倾向在一定程度上导致了当前工程事故频发、构造使用性能差、使用寿命短的不良后果；也与国际构造工程界日益重视耐久性、平安性、适用性的趋势相违背；也不符合构造动态与综合经济性的要求。 桥梁平安性、耐久性差的主要原因 1施工与管理水平低 国内外多座桥梁的突然破坏与倒塌，已使工程界对桥梁平安性问题倍加关注。一般的看法认为当前的工程事故主要是野蛮施工与管理腐败所导致。对于短期内发生的诸如突然破坏与倒塌，多是由于施工质量没有到达标准与设计要求，典型的问题包括材料强度缺乏与

47、施工工艺不合格等；也有个别桥梁存在诸如偷工减料、以次充好等严重的管理问题，更是对桥梁平安造成致命的损害。 而大量的桥梁在远没有到达预期使用寿命时，出现了影响正常使用的病害与劣化；特别是一些桥梁在只使用了几年、甚至刚建成不久就出现严重的耐久性缺乏的问题，这也与施工质量低下有重要关系，典型的问题有钢筋保护层缺乏及目前广泛存在于施工现场的严重的构件开裂问题。这些施工上的缺陷虽然短期不会对桥梁的正常使用产生明显的影响，但却会对构造的长期耐久性产生非常不利的危害。 2设计理论与构造构造体系不够完善 在成认施工存在问题的同时，也不可否认，在桥梁设计领域，特别是关于桥梁施工与使用期平安性的问题还有许多可以改

48、良的地方。构造设计的首要任务是选择经济合理的构造方案，其次是构造分析与构件与连接的设计，并取用标准规定的平安系数或可靠性指标以保证构造的平安性。 许多设计人员往往只满足于标准对构造强度计算上的平安度需要，而无视从构造体系、构造构造、构造材料、构造维护、构造耐久性以及从设计、施工到使用全过程中经常出现的人为错误等方面去加强与保证构造的平安性。有的构造整体性与延性缺乏，冗余性小；有的计算图式与受力路线不明确，造成局部受力过大；有的混凝土强度等级过低、保护层厚度过小、钢筋直径过细、构件截面过薄；这些都削弱了构造耐久性，会严重影响构造的平安性。不少桥梁、虽然满足了设计标准的强度要求，仅用了510年就因

49、为耐久性出了问题影响构造平安。构造耐久性缺乏已成为最现实的一个平安问题，设计时要从构造、材料等角度采取措施加强构造耐久性。 不同的环境与使用条件、不同的设计对象都会对构造体系提出不同的布局与构造等方面的要求。标准再详细也不能包罗本应由设计人员解决的各种问题、标准更新得再快也适应不了新认识、新技术、新材料快速开展对构造提出的各种新的要求。因此，合理可靠的构造设计除了满足标准的要求外，还要求设计人员具有对构造本性的正确认识、丰富的经历与准确的判断。 需要改良与努力的方向 1应该更加重视构造的耐久性问题 桥梁在建造与使用过程中，一定会受到环境、有害化学物质的侵蚀，并要承受车辆、风、地震、疲劳、超载、人为因素等外来作用，同时桥梁所采用材料的自身性能也会不断退化，从而导致构造各局部不同程度的损伤与劣化。在大跨桥梁领域，国内从上世纪80年代以来，修建了大量的斜拉桥；虽然迄今为止出现倒塌或严重损害的例子很少，但已经有多座桥梁因为拉索的耐久性问题而不得