输水管道水锤效应作用下斜拉桥结构动力响应研究

摘要

In order to study the dynamic response of cable-stayed bridge induced by the water hammer action in the large-scale water pipeline laid on the bridge,a single-tower cable-stayed bridge was investigated,and the dynamic effect of pipeline was simplified as the dynamic loading.By establishing the pipeline water hammer calculation model and bridge dynamic calculation model,respectively,the bridge-downward impact force at the valve and its variation with time can be obtained when the water hammer effect occurs.Furthermore,the impact force is taken as the dynamic loading and applied to the bridge model.The calculation results suggest that the impact force of water hammer may vary periodically,and relatively large impact loading is generated when the valve is switched off in a short time.The dynamic responses of various components of single-tower cable-stayed bridge under water hammer impact are mainly in the bridge-downward direction with accompanied vertical displacement and stress.The stress changes in girder can be neglected,and stress variations in tower and stayed cables can approach 0.7MPa and 1.5MPa,respectively.The pipeline laid at single side may produce eccentric effect,leading to the nonsymmetric dynamic response of structure.%为研究斜拉桥上铺设的大型输水管道发生水锤效应时桥梁结构的动力响应,以某独塔斜拉桥为工程背景,根据水锤效应的基本理论和作用方式,将管道对桥梁的动力效应简化为一随时间变化的动力荷载.通过分别建立管道水锤计算模型和桥梁动力计算模型,得到水锤效应发生时阀门位置顺桥向冲击力随时间的变化情况,再将此冲击力作为动力荷载施加到桥梁模型上.计算结果表明:水锤冲击力随时间呈周期性变化,阀门短时间关闭时将产生较大的冲击荷载;漂浮体系独塔斜拉桥各构件在水锤冲击作用下的动力响应以顺桥向方向为主,同时伴随有竖向的位移与应力.主梁上的应力变化可忽略不计,桥塔及斜拉索中应力变化分别可达0.7MPa和1.5MPa左右.单侧布置的管道还会产生偏心作用,使结构的动力响应呈现非对称性.