大型橋梁及施工外文翻譯--大跨度橋梁-橋梁設(shè)計-文庫吧資料
2025-05-22 04:22本頁面
【正文】 due to wind might result in the collapse of the structure, as illustrated in the tragic failure in 1940 of the first Taa Narrows Bridge. The side span to main span ratio varies from to .The span to depth ratio for the stiffening truss in existing bridge lies between 85 and 100 for spans up to 1,000m and rises rather steeply to 177. The ratio of span to width of deck for existing bridges ranges from 20 to 56. The aerodynamic stability will have be to be investigated thoroughly by detailed analysis as well as wind tunnel tests on models. 2. The cablestayed bridge During the past decade cablestayed bridges have found wide application, s\especially in Western Europe, and to a lesser extent in other parts of the world. The renewal of the cablestayed system in modern bridge engineering was due to the tendency of bridge engineering in Europe, primarily Germany, to obtain optimum structural performance from material which was in short supplyduring the postwar years. Cablestayed bridges are constructed along a structural system which prises an 1 orthotropic deck and continuous girders which are supported by stays, . inclined cables passing over or attached to towers located at the main piers. The idea of using cables to support bridge span bridge span is by no means new, and a number of examples of this type of construction were recorded a long time ago. Unfortunately the system in general met with little success, due to the fact that the statics were not fully understood and that unsuitable materials such as bars and chains were used to form the inclined supports or stays. Stays made in this manner could not be fully tensioned and in a slack condition allowed large deformations of the deck before they could participate in taking the tensile loads for which they were intended. Wide and successful application of cablestayed systems was realized only recently, with the introduction of highstrength steels, orthotropic decks, development of welding techniques and progress in structural analysis. The development and application of electronic puters opened up new and practically unlimited possibilities for exact solution of these highly statically indeterminate systems and for precise stoical analysis of their threedimensional performance. Existing cablestayed bridges provide useful data regarding design, fabrication, erection and maintenance of the mew system. With the construction of these bridges many basic problems encountered in their engineering are shown to have been successfully solved. However, these important data have apparently never before been systematically presented. The application of inclined cable gave a new stimulus to construction of large bridges. The importance of cablestayed bridges increased rapidly and within only one decade they have bee so successful that they have taken their rightful place among classical bridge system. It is interesting to note now how this development which has so revolutionized bridge construction, but which in fact is no new discovery, came about. The beginning of this system, probably, may be traced back to the time when it was realized that rigid structures could be formed by joining triangles together. Although most of these earlier designs were
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