土木工程专业英语(桥梁)教案.ppt

Cantilever . Often it is not feasible to construct long span bridges by means of intermediate piers. In deep swift-running rivers or in soft subsoil, for example, it may be difficult to construct the piers or to make them deep enough to reach a firm foundation rock. 悬臂。利用中间桥墩方式，建造大跨度桥通常是不可行的。举个例子，在深而流速急的河流或软泥中，很难建造墩使它有足够深度达到基岩层。 In such cases the span of a rigid-beam structure can be extended simply by using two beams-one extending from each bank –with one end of each beam firmly anchored to its foundation, rather than simply resting on it as in ordinary rigid-beam construction. 在这种情况下，刚性梁结构用两根梁就可以延伸——从每岸伸出一根梁——而在两根梁的端部基础进行锚固，这一点与普通刚性梁不同。 * Each of the anchored beams in this kind of structure is called a cantilever. Perhaps the simplest familiar example of a single cantilever is the familiar diving board. 每一根锚固的梁称之为悬臂，或许这种最简单而熟悉的悬臂例子便是跳水板。 In an ordinary cantilever bridge, the gap between the ends of the cantilevers is closed, providing a continuous deck for the roadway, but if the bridge were cut in two at the point of closure each cantilever would support itself. 在普通的悬臂式桥梁中，悬臂梁端部之间的间隙是闭合的，为道路提供了连续的桥面。但是假如把这种桥梁在其闭合点断开，那么每一根悬臂梁都不需要另外设置支撑而可保持稳定。 Usually the gap between the cantilevers is closed by means of a rigid beam , thus extending the span of the cantilevers. 通常悬臂梁中间间隙使用刚性梁来闭合，这样，可延伸悬臂梁的跨度。 * Suspension. Suspension bridges can span even greater distances without intermediate piers than can cantilever bridges. 悬索。在没有中间桥墩的情况下，悬索桥比悬臂桥跨越更大的距离。 The supporting members of a suspension bridge are continuous flexible cables, with each cable anchored at both of its ends. 悬索桥的支撑体系是两端锚固的连续可弯曲的缆绳。 * The simplest example of the suspension bridge is the circus aerialist’s tightrope, and primitive suspension bridges were often no more than several such tightropes tied together to provide both hand and foot holds . 悬索桥最简单的例子是杂技场高空走钢丝杂技演员用的钢丝。原始的悬索桥常常是一把很小的几根这样的钢丝系在一起来提供扶手和立足点的。 In modern suspension bridges a level roadway