大质量法在桥梁非一致弹塑性地震响应分析中的误差与改进  

Error analysis and improvement of the large mass method used in elastic-plastic response analysis of bridges subjected to non-uniform seismic

作　　者：雷虎军 黄炳坤 刘伟 黄江泽 LEI Hujun;HUANG Bingkun;LIU Wei;HUANG Jiangze(College of Civil Engineering,Fujian University of Technology,Fuzhou 350118,China;Fujian Provincial Key Laboratory of Advanced Technology and Informatization in Civil Engineering,Fuzhou 350118,China)

机构地区：[1]福建工程学院土木工程学院,福州350118 [2]福建省土木工程新技术与信息化重点实验室,福州350118

出　　处：《振动与冲击》2020年第22期28-34,共7页Journal of Vibration and Shock

基　　金：国家自然科学基金项目(51878173,51608120);福建省高校杰出青年科研人才培育计划项目(GY-Z18159)。

摘　　要：针对大质量法计算大跨桥梁非一致弹塑性地震响应可能存在的误差。基于结构弹塑性分析理论,以某(56+100+56)m大跨连续刚构桥为工程背景,采用Midas Civil 2015建立弹塑性分析模型并利用大质量法处理模型边界形成非一致弹塑性分析模型,通过输入3条实测地震波计算结构的弹塑性地震响应,探讨了大质量法存在的误差并提出了修正方法。结果表明:大质量法直接用于求解桥梁结构的非一致弹塑性地震响应存在误差,会使求得的桥墩关键断面弯矩偏小,其根本原因是大质量法改变了结构的边界条件,使固定约束改为滑动约束,导致求得的恒载弯矩偏小;通过在原大质量法中沿地震动输入方向添加刚度为K的弹性约束同时按照公式ug+αu·g+u g修正输入地震波可实现大质量法的高精度修正,K可与大质量系数M取相同值;对于相应的计算条件,修正后的大质量法求得的桥墩关键断面弹塑性弯矩相对误差降低至0.135%;研究成果可用于任意大跨结构的非一致弹塑性地震响应计算。Aiming at the error of the large mass method(LMM)used in elastic-plastic responses analysis of long-span bridges subjected to non-uniform seismic,a continuous rigid frame bridge with spans of(56+100+56)m was used as an engineering background.Based on the elastic-plastic theory,the non-uniform elastic-plastic analysis model set up by Midas Civil 2015 was utilized,in which the boundary conditions were modeled by the LMM.Then,the elastic-plastic seismic responses of the bridge were calculated by inputing three field measured seismic waves,the error of LMM was discussed,and the improved method for the LMM was proposed.The results show that there are errors resulted from the LMM used in elastic-plastic seismic responses analysis of long-span bridges and the bending moment at the key section of the bridge pier tends to be smaller.The fundamental reason is that the LMM changes the boundary conditions of the structure,it changes the fixed constraints into the sliding constraints,and results in less bending moment under constant load.By adding an elastic constraint with stiffness of K along the input direction of ground motion in the original LMM and modifying the input seismic wave according to the formula ug+αu·g+u g,a high-precision correction of the LMM was realized,where K took the same value as the large-mass coefficient M.With the calculation condition in the paper,the relative error of the elastic-plastic bending moment at the key section of bridge pier is reduced to 0.135%by the modified LMM.The results can be used to calculate the non-uniform elastic-plastic seismic response of large span structures.

关 键 词：连续刚构桥 大质量法(LMM) 一致激励法 弹塑性分析 恒载效应 

分 类 号：U24[交通运输工程—道路与铁道工程] TB123[理学—工程力学]