不同截面类型简支梁桥动力冲击系数研究  

Dynamic impact factors for simply supported bridges with different cross-section types

作　　者：邓露[1] 何维[1] 王芳[1] 

机构地区：[1]湖南大学土木工程学院,长沙410082

出　　处：《振动与冲击》2015年第14期70-75,共6页Journal of Vibration and Shock

基　　金：国家自然科学基金(51208189);湖南省杰出青年基金(14JJ1014)

摘　　要：针对我国《公路桥涵设计通用规范》JTJ 021-89及JTG D60-2004中分别采用跨度、基频计算桥梁动力冲击系数IM时均只考虑影响车桥耦合振动中一个因素不够准确问题,基于通用图集建立5座桥梁有限元模型,并用数值方法计算设定工况下的IM。将计算结果与两种规范设计值进行对比;分别比较跨径、基频相同的不同截面类型桥梁IM差异。结果表明,中等路面桥梁的IM计算结果较04规范设计值小,与89规范较接近;差路面情况下两规范设计值均远小于IM计算结果;不同截面桥梁的IM相差较大,说明仅用跨径或基频计算动力冲击系数不完全合理,由桥梁截面类型引起的动力冲击系数差异不可忽视。In the General Code for Design of Highway Bridges and Culverts,namely,JTJ 021-89 and JTG D60-2004,the impact factor （IM）is specified as the function of the length of bridge span and the fundamental frequency of bridge,respectively.These codes provisions consider only one parameter that has influence on vehicle-bridge interaction system.However,some studies have suggested that the use of single parameter may be insufficient to account for dynamic impact of moving vehicles.In this study,the finite-element models of five bridges based on standard drawings were built. The IMs of these bridges were calculated using numerical methods suitable for different cases.The rationality of code provisions was examined.The IMs for bridges of three different cross sections with the same span length and fundamental frequency were then compared.The results show that：under average road surface condition,the IMs calculated are lower than those specified in JTG D60-2004 but are relatively consistent with these specified in JTJ 021-89,nevertheless,under poor road surface condition,both design codes significantly underestimate the IM;there exists significant variation of IM for bridges with the same span length and fundamental frequency but different cross sections,indicating that evaluating IM using either span length or fundamental frequency alone is not accurate generally and engineers should also pay attention to the difference in IMdue to cross-section types.

关 键 词：车桥耦合振动 动力冲击系数 规范设计值 数值模拟 有限元 

分 类 号：U44[建筑科学—桥梁与隧道工程]