大跨异形钢管混凝土拱桥车载冲击效应分析

大跨度异形钢管混凝土拱桥的复杂造型使其结构动力特性极为特殊,车辆激励引起的桥梁振动十分复杂.为研究该类桥梁车辆冲击效应的特点和规律,以在建的长春市伊通河大桥为对象,应用自编的车桥耦合振动分析程序,对该桥进行了车桥耦合振动响应分析.从理论上分析了路面粗糙度、车速、结构阻尼对桥梁主梁、拱肋挠度和吊杆索力冲击效应的影响.结果表明:路面不平度对多拱肋异型拱桥振动响应的影响十分显著,维持路面平整可有效降低冲击系数;行车速度对冲击效应的影响与发生的卓越振动振型密切相关,并不一直随车速成正比增大;结构阻尼值在规范给定范围内变动时,对冲击系数影响不明显,设计中可偏安全地取阻尼比为0.5%.研究给出了该桥各主要构件的设计冲击系数取值的参考范围.

Impact effect study on long-span irregular concrete filled steel tube arch bridge under moving vehicles

A long span irregular CFST arch bridge has very special dynamic characteristics for its complex form. Bridge vibration caused by moving vehicles is also very complicated. In order to research impact effect characteristic of the bridge type, in this paper, the dynamic response analysis of vehicle and bridge interaction was carried out for the under-construction Yitong river bridge in Changchun city by the self-compiling computing program. The influence of road surface roughness, vehicle speed and damping on impact effect of bridge was studied by theory analysis. The following conclusions can be drawn according to analyzing results: the effect of road surface roughness on vibration response of irregular arc bridge is significant, keeping good roughness level would decreased impact factor; The effect of vehicle speed on impact factors is related with the primary modes inducing the response, and hence increasing vehicle speed may not increase impact factors; Damping ratio of structure does not affect impact factors significantly when it changed in given scope by specification, 5% can be used in design on security. At last, impact factor referent value of the bridge was given in the study.