土木工程专业英语[武汉理工大学出版社]lesson8.pptVIP

§8 Bridge Design and Construction桥的设计与建造; Planning. The first step leading to the construction of a modern major bridge is a comprehensive study to determine whether a bridge is needed. 规划设计 现代重要的桥梁建造的第一步是广泛地研究以确定桥梁的必要性。 If it is to be a highway bridge, in the United States for example，a planning study is initiated by a state bridge authority，possibly in cooperation with local government or the federal government . 比如：如果是美国的高速公路桥，是由州桥管理局研究规划并确定，同时当地的政府或联邦政府一起参与。; Studies are made to estimate the amount of bridge traffic, the relief of jammed traffic in nearby highway network, the effects on the regional economy, and the cost of the bridge. 桥梁的交通流量、对附近高速公路网交通堵塞的调剂，对当地经济的影响和桥的造价等因素进行评估研究。 The means for financing the project, such as public taxes or sale of revenue bonds repaid by toll charges, are considered. Bond n.结合(物), 粘结(剂), 联结, 公债, 债券, 合同 revenue bond收益债券 这就决定了工程的投资方式，如公众收费，依靠过通行费来支付的发行债券的规模都要被考虑进来。 If the studies lead to a decision to go ahead with the project, the land needed for the bridge and its approaches is acquired at the selected site. 如果研究认为其可行信，那么桥选址和占地问题将着手处理。; At this point, field engineering work is started. Accurate land surveys are made. land survey 土地测量 在确定场地时，现场测绘工作开始进行，做好精确的实地测量。 Tides, flood conditions，currents, and other characteristics of the waterway are carefully studied. 潮汐，洪水因素，水流和排水的其它的特征都要仔细研究， Boring samples of soil and rock are taken at possible foundation locations, both on land and under the water. 在陆地和水下的泥土和岩石的钻孔取样在基础可能的位置都要尽可能地进行。; Selection of bridge design.桥梁设计类型的选择 The chief factors in deciding whether a bridge will be built as a girder , cantilever , truss , arch , suspension , or some other type are： (1) location；for example, cross a river ;(2)purposes ; for example , a bridge for carrying motor vehicles ; ( 3 ) span length ; ( 4 ) strength of available materials ; ( 5 ) cost ; ( 6 ) beauty and harmon