大型橋梁及施工外文翻譯--大跨度橋梁-橋梁設(shè)計(存儲版)
【正文】 amples 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 based on sound principles and assumptions, the girder stiffened by inclined cables suffered various misfortunes which regrettably resulted in abandonment of the system. Nevertheless, the system in itself was not at all unsuitable. The solution of the problem had unfortunately been attempted in the wrong way. The renaissance of the cablestayed, however, was finally successfully achieved only 1 during the last decade. Modern cablestayed present a threedimensional system consisting of stiffening girders, transverse and longitudinal bracings, orthotropictype deck and supporting parts such as towers in pression and inclined cables in tension. The important characteristics of such a threedimensional structure is the full participation of the transverse construction in the work of the main longitudinal structure. This means a considerable increase in the moment of inertia of the construction which permits a reduction in the depth of the girders and economy in steel. Long span concrete bridges are usually of posttensioned concrete and constructed either as conditions beams types or as free versatile structures. Many methods have been developed for continuous deck construction. If the clearance between the ground and bottom of the deck is small and the soil is firm, the superstructure can be bu
畢業(yè)設(shè)計相關(guān)推薦
鄂ICP備17016276號-1