摘要
非一致激励其破坏性效应复杂,大跨结构地震反应计算时应合理考虑其影响。该研究针对位移输入法(displacement input method,DIM)计算大跨结构非一致地震响应时存在的误差和来源展开研究。采用Rayleigh阻尼假定,分析了某长跨桥梁结构的地震反应及误差,指出了DIM对不同地震动效应的适用性和误差产生的原因。而后讨论了差动激励的常用算法和模拟理论的差异,最后提出了改进的位移输入法(improved displacement input method,IDIM),并进行了验证。结果表明:DIM用于求解大跨结构的非一致地震响应时存在不可忽略的误差,其大小与输入的地震动特性和刚度比例阻尼系数β相关,且随着β的增大而增大。DIM误差来源于忽略了C_(ts)△X_(s)阻尼项(与地震动增量速度和β相关);通过2种IDIM与已有方法对比可知,DIM对于脉冲地震动作用和β较大的情形(较长自振周期)不再适用;所提出的IDIM对于多点激励结构反应计算精度好、算法易用且可靠。最后建议了通用的非一致地震激励结构反应分析流程,考虑了近断层效应、残余位移等并最小化了大刚度、大质量法的舍入误差,研究成果可推广用于大型结构非一致激励的动力响应计算。
The potential damage effects of spatial seismic ground motions are leading to complicated structure response.They should be considered reasonably in seismic response calculation.In this study,the errors and sources of the displacement input method(DIM)in the calculation of non-uniform seismic response of long-span structures were studied.Considering Rayleigh damping,the seismic responses and errors from different calculation methods for the long-span bridge structure were analyzed.The applicability of DIM under the influence of different types of ground motions were tested,and the reasons for the errors were given.Then,the difference between commonly used multi-point excitation input algorithms and simulation theory was discussed.Finally,the improved displacement input method(IDIM)was proposed and verified.Results show that when DIM is used to solve the non-uniform seismic response of long-span structures,there is an error that cannot be ignored.The magnitude of error is related to the characteristics of input ground motion and the stiffness proportional damping coefficient,β.And it increases withβ.DIM error comes from neglecting the damping term of C_(ts)△X_(s)(which is related to the incremental velocity of ground motion andβ).By comparing with the existing methods,DIM is no longer suitable for the cases of pulse-like ground motions and largeβ(long natural period).Further,the IDIM proposed are of good accuracy,easy to implemented and reliable for structure analysis subjected to multi-support excitation.At last,a general flow chart of structural response analysis under non-uniform seismic excitation was proposed,which takes pulse effect and residual displacement into account and avoids the rounding error of large stiffness and large mass methods.The results can be applied to dynamic response analysis of large structures subjected to non-uniform seismic excitations.
作者
李宁
陈浩
李忠献
LI Ning;CHEN Hao;LI Zhongxian(Key Laboratory of Coast Civil Structure Safety,Ministry of Education,School of Civil Engineering,Tianjin University,Tianjin 300350,China;Key Laboratory of Earthquake Engineering Simulation and Seismic Resilience of China Earthquake Administration,Tianjin University,Tianjin 300350,China)
出处
《振动与冲击》
EI
CSCD
北大核心
2022年第16期85-92,共8页
Journal of Vibration and Shock
基金
国家重点研发计划(2019YFE0112500,2018YFC1504306)
国家自然科学基金(51678407
51427901)。
作者简介
第一作者:李宁,男,博士,教授,1981年生。
