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一、国外桥梁建设的发展趋势和特点 1.国外桥梁建设的发展趋势随着人类社会的发展,对于交通运输的要求日益增长。公路、铁路是主要的交通运输命脉,其中桥梁则是这些运输线路的重要组成部分。19世纪初熟铁开始用作建桥材料,至19世纪中叶,钢材的出现进一步促进了桥梁建设的发展。当时,正是欧美各国大量修建铁路之际,相应修建了不少铁路桥梁。在桥梁跨度和型式上有了很大发展,如建于1855年的尼亚加拉瀑布(Niagara Falls)的悬索桥,主跨为821英尺(250.24m);建于1874年的圣路易斯(St.Louis)桥,跨度为497+515+407英尺(151.49+156.97+
First, the development trend and characteristics of foreign bridge construction 1. The development trend of foreign bridge construction With the development of human society, the requirements for transportation are increasing day by day. Roads and railways are the main transport lifebloods, of which bridges are an important part of these transport routes. Early 19th century iron began to be used as a bridge construction material. By the middle of the 19th century, the advent of steel further promoted the development of the bridge construction. At that time, it was exactly the time when a large number of railroads were built in various countries in Europe and the United States that a lot of railroad bridges were constructed. Great strides have been made in the span and type of bridges, such as the suspension bridge built at Niagara Falls in 1855, with a main span of 821 feet (250.24 meters); the St. Louis Bridge built in 1874, The span is 497 + 515 + 407 feet (151.49 + 156.97 +