考虑脉冲效应的近断层地震动能量谱研究  

Energy spectrum of near-fault ground motion considering pulse effects

作　　者：陈曦[1,2] 陈清军[1,2] 廖聪 CHEN Xi;CHEN Qingjun;LIAO Cong(State Key Lab of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Department of Disaster Mitigation for Structures,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程防灾减灾全国重点实验室,上海200092 [2]同济大学结构防灾减灾工程系,上海200092

出　　处：《振动与冲击》2024年第22期305-317,共13页Journal of Vibration and Shock

基　　金：国家自然科学基金(51778489);科技部国家重点实验室基础研究资助项目(SLDRCE19A-02)。

摘　　要：基于能量的设计方法被广泛应用于结构抗震设计与性能评估,而确定结构能量耗散需求是设计过程中需解决的首要问题。目前针对近断层脉冲型地震动能量谱特征的研究仍然不够充分,很可能低估其对结构的破坏作用。为此,从PEER(Pacific Earthquake Engineering Research Center)强震数据库中选取了789条近断层地震动作为输入,并从中识别出192条脉冲型地震动,重点分析了近断层脉冲型地震动与无脉冲地震动的能量谱差异,研究了地震动特征参数及恢复力模型参数对能量谱的影响,并建立了考虑脉冲效应的近断层地震动实用设计能量谱。结果表明:(1)场地越软,近断层地震动能量谱谱值越大,且各类场地下脉冲型地震动能量谱平均谱的谱值明显大于无脉冲地震动;(2)阻尼比ξ增大对输入能量谱具有削峰作用,并减缓其长周期段的衰减速度,延性比μ增大会提高输入能量谱及阻尼耗能谱峰值,并降低滞回耗能谱峰值,屈服后刚度比α对能量谱影响较小,可近似忽略其影响;(3)脉冲型地震动的输入能量设计谱平台段长度远大于无脉冲地震动,所建立的设计能量谱可为近断层区域基于能量的抗震设计提供参考。Energy-based design methods play a pivotal role in the seismic design and performance evaluation of structures.A critical initial step in the design process is to determine the energy dissipation requirements.Notably,existing studies often overlook characterizing near-fault pulse-like ground motions,potentially underestimating the damaging effects of pulse-like motions.789 near-fault ground motions were selected as inputs from the Pacific Earthquake Engineering Research Center(PEER) earthquake database,with 192 pulse-like ground motions identified among them.The energy spectra differences under various seismic characteristic parameters and resilience model parameters were systematically compared.The practical design input energy spectrum for the near-fault ground motion,considering pulse effects,was established.Key findings include:(1)softer sites yield larger spectral values for near-fault ground motion energy spectra.Importantly,the average spectral value of pulse-like ground motions exceeds that of pulseless ground motions under different site conditions.(2)The damping ratio ξ clips the input energy spectrum,decelerating long-period section attenuation.The ductility ratio μ increases the peak values of input energy and damping dissipation spectra while reducing the peak values of hysteretic dissipation spectrum.The post-yield stiffness ratio α minimally impacts the energy spectrum.(3)The platform segment length of the input energy design spectrum for pulse-like ground motions is notably larger than that for pulseless ground motions.The established design energy spectrum can serve as a reference for the energy-based seismic design in near-fault regions.

关 键 词：近断层地震动 速度脉冲 能量谱 输入能量设计谱 

分 类 号：TU311.3[建筑科学—结构工程]