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概论一、桥梁演进:通都大邑,往往有通航河道,穿贯其中,将一大城市划分为二,如天津的海河和运河,上海的黄浦江和苏州河,武汉的长江、汉水,广州的珠江,诸如此类,为数不少。为水陆交通双方兼顾计,从前多设立浮桥,如天津的老东浮桥,上海的老外白渡桥等。嗣后市内交通日形发达车辆载重日增,复以汽车电车通行,而老式浮桥渐不适应现代交通工具的要求;河上船舶,由帆船改进为汽轮,高大无比,而桥下水上的净空又大为增高,因而将旧式浮桥改建为开关活动桥梁,如天津解放桥、
Introduction First, the evolution of the bridge: Dayu Dayu, there are often navigable rivers, which runs through, will be a major city is divided into two, such as the Haihe River and the canal in Tianjin, Shanghai Huangpu River and Suzhou River, the Yangtze River in Wuhan, Han River, Pearl River in Guangzhou, and so on, a large number. For both water and land transport account, in the past more than the establishment of pontoon, such as the old pontoon in Tianjin, Shanghai’s foreigner White Bridge and so on. Subsequent urban traffic day-shaped vehicles carrying an increasing number of complex, with the car tramway, and the old-style pontoon gradually adapt to the requirements of modern transport; river vessels, sailing improved steam turbine, very large, and the bridge under the water headroom and Greatly increased, so the old pontoon converted into a switch activity bridge, such as Tianjin Jiefang Bridge,