长周期地震动的能量反应谱

Energy Response Spectra of Long-period Ground Motions

选取139条长周期地震动记录作为输入,研究了恢复力模型参数(恢复力模型、刚度比η、阻尼比ξ、位移延性比μ)和地震动特性(周期T、震级M_W、场地、PGA)对长周期地震的输入能量谱S_(EI)、滞回耗能谱S_(EH)和阻尼耗能谱S_(ED)的影响.研究表明:1)恢复力模型对长周期(常规)地震能量谱的影响很大(小);η对长周期和常规的地震动的能量谱的影响都很小;随着ξ增加,长周期(常规)地震的S_(EI)的长周期段谱值增大(减小);随着μ增加,长周期(常规)地震的S_(EH)的峰值平台段延长(缩短)且峰值降低(增大).2)M_W越大,结构损伤越大;场地土越软,能量谱值越大;若已知基准PGA_(ref)的能量谱,其他PGA_(oth)的能量谱可由(PGA_(oth)/PGA_(ref))^(2)调整得到.基于以上的参数影响研究,采用三段式拟合函数,建立了长周期地震弹性输入能量设计谱,并拟合了μ和ξ对长周期地震能量谱的影响公式,进而得到长周期地震非弹性输入能量设计谱.

A total of 139 long-period ground motion(GM)records are selected to study the effects of the parameters of restoring force models(restoring force models,stiffness ratioη,damping ratioξ,displacement ductility ratioμ)and GM characteristics(period T,earthquake magnitude MW,site,PGA)on the input energy spectra SEI,hysteretic energy spectra SEH and damping energy spectra SED of the long-period GMs.Therefore,it can be found that:1)there is a significant(slight)influence of the restoring force model on the long-period(conventional)seismic energy spectra,while there is a slight influence of the restoring force model on the conventional one;there is a slight influence ofηon the long-period and conventional seismic energy spectra;with the increase ofξ,the spectral values in the long-period region of the long-period SEI increases,but for the conventional one it decreases;with the increase ofμ,the peak platform and peak value of the long-period SEH is prolonged and decreases,but for the conventional one they are shortened and increases,respectively.2)the larger MW results in the greater structural damage,while the softer site soil leads to the larger energy spectra value;the seismic energy spectra with other PGAoth can be obtained by multiplying the known seismic energy spectra with the reference PGAref by the equation of(PGAoth/PGAref)2.Then,based on the above parametric studies,the elastic long-period input energy design spectra are established by using a three-segment fitting function,and the influence formulas ofμandξon the long-period spectra are fitted.And then the inelastic long-period input energy design spectra are obtained.