多塔悬索桥活载效应简化分析  

Simplified Analysis of Live Load Responses in Multi-tower Suspension Bridges

作　　者：孙斌[1] 胡志坚[2] 张力文[1] 秦一栋 肖汝诚[1] 

机构地区：[1]同济大学土木工程学院,上海200092 [2]武汉理工大学交通学院,湖北武汉430063

出　　处：《中国公路学报》2015年第11期60-66,81,共8页China Journal of Highway and Transport

基　　金：国家重点基础研究发展计划("九七三"计划)项目(2013CB036303);国家自然科学基金项目(51008223)

摘　　要：为简化多塔悬索桥在活载作用下变形与内力的计算,将相邻跨主缆对加载跨主缆的约束效应等效为主缆弹簧,并基于全微分理论和平衡方程推导得到了等效主缆弹簧刚度,再计入桥塔抗推刚度后得到了加载跨主缆两端的总约束刚度;采用单位集中荷载加载得到活载位移影响线,进而得到活载作用下的结构响应;与有限元分析结果进行对比以验证该方法作为概念设计阶段可靠估算方法的可行性。结果表明:与典型双塔悬索桥不同,多塔悬索桥位移影响线在加载跨内几乎不出现变号区域,且最大位移发生在跨中附近,对应全跨满布活载的加载方式;参数分析表明桥塔刚度增大有助于提高结构总刚度,但桥塔弯矩也随之增大;桥塔刚度较小时结构竖向刚度随主缆垂跨比增大而减小,桥塔刚度较大时规律相反;所提出的计算方法可作为概念设计阶段的可靠估算方法。In order to simplify the calculation of deflection and internal forces of multi-tower suspension bridges under the live load,the restriction effect of the main cables in adjacent spans on the loaded span was equivalent to cable springs.The cable spring＇s stiffness was derived through total differential theory and structural equilibrium equation.The restriction stiffness at both ends of the main cable in the loaded span was derived after taking the tower rigidity into account.Then,the structural responses of multi-tower suspension bridges under the live load were investigated by using the influence line of displacement which was derived through the deflection profile of the bridge under a unit concentrated force.Comparison with the results from FEM analysis showed that the simplified analytical method was a reliable method for conceptual design.The results show that different from that of typical suspension bridges with two towers,the displacement influence line in multi-tower suspension bridges keeps being downward all over the loaded span.Moreover,the maximum displacement occurs approximately at the middle of main span,which corresponds to the load method all over the loaded span.The parameter study shows that a larger tower rigidity increases the total structural stiffness of the bridge,while the bending moment in the tower increases at the same time.When the tower rigidity is smaller,thevertical structural stiffness decreases with the increase of the cable sag ratio,while the tendency turns to the opposite side with a larger tower rigidity.The proposed calculation method can act as a reliable estimation method at the stage of conceptual design.

关 键 词：桥梁工程 多塔悬索桥 简化分析 活载效应 主缆弹簧 等效刚度 位移影响线 

分 类 号：U442.5[建筑科学—桥梁与隧道工程]