弹塑性时程分析中地震动输入处理方式影响

IMPACT OF STRONG GROUND MOTION'S PROCESS PROCEDURE ON THE STRUCTURAL NONLINEAR TIME-HISTORY ANALYSIS

以包含残余永久位移和(或)速度脉冲的强震动记录为重点分析对象,针对强震动滤波以及基线校正方式等不同处理方式对结构弹塑性响应的影响展开对比研究。考虑了多项式基线校正,Butterworth因果滤波,以及基于残余位移趋势线基线校正等几种常用的强震动记录处理流程和方法。首先以2018年台湾花莲地震,2014年云南鲁甸地震,日本311地震等代表性的强震动记录为输入,通过单(多)自由度体系以及典型平面RC框架的数值模拟结果,从结构弹塑性反应谱,层延性需求,以及最大层间位移角等方面对比研究了不同记录处理方式的影响。对比结果表明速度脉冲形状与相位是否完整保留对于结构的弹塑性响应有很大影响,对于包含速度脉冲或(及)永久位移的强震动记录,Butterworth因果滤波在滤除噪声的同时不仅消除了地表残余永久位移,同时使速度脉冲形状产生了畸变,并会传递到最后的弹塑性时程分析结果中,且对短,中,长周期结构均可能产生影响,该文推荐采用基于基线趋势线校正的处理方法对该类近断层记录进行逐条处理。最后,对于不含速度脉冲也不含永久位移的强震动记录,该文中弹塑性时程分析结果表明记录处理方式的影响并不显著。为了尽量消除因果滤波对记录时程相位谱的影响,我们给出了基于非因果滤波的批量化强震动记录处理流程供参考。

In this study,we focus on the records with permanent displacement and(or)velocity pulse and compared the impact of different process procedures on structural responses.We firstly classified the strong ground motion into four categories and picked typical records from different earthquake events,e.g.2018 Taiwan Hualien earthquake,2014 Ludian earthquake in Yunnan,and the 2011 Tokyo earthquake in Japan.These records were processed using different filtering and baseline correction process methods.The corresponding SDOF/MDOF inelastic demand and EDPs of RC frames were computed and compared.For the records with pulse-like velocity and(or)permanent displacement,the Butterworth filtering method will significantly distort the pulse portion and erase the permanent displacement,which will further influence structural responses regardless of the structural fundamental periods.For this kind near-fault ground motion,it is recommended to use the baseline trend line correction processing method before structural time-history analysis.For ground motions without pulse-like velocity and permanent displacement,the process procedure have a negligible effect on structural responses.In order to eliminate the effect of causal filtering on the time-history’s phase spectrum,we propose a batch-processing procedure based on a causal Butterworth filtering method.