不同频谱特性输入地震动对场地设计地震动反应谱的影响

Influence of Input Ground Motions with Different Spectral Characteristics on the Response Spectra of Design Ground Motion

频谱特性是地震动的三要素之一,具有不同频谱特性的输入地震动对场地设计地震动反应谱会产生不同影响效果。基于一维土层地震反应分析计算方法,选取4条历史地震实测记录[1989年美国加州洛马普列塔(Loma Prieta)6.9级地震、1994年美国加州北岭(Northridge)6.6级地震、2008年汶川8.0级地震和2013年甘肃岷县漳县6.6级地震]和1条典型人工合成地震动(濮阳市人工拟合地震动)进行对比,研究具有高频和低频特性的输入地震动对场地设计地震动反应谱的影响。结果表明,以高频成分为主的历史地震动较以低频为主的人工拟合波对反应谱的影响表现为在短周期阶段具有集中放大的影响效果。这主要表现在两个方面:其一,对峰值平台值具有放大效果,历史地震动结果峰值平台值为2.75～2.80间,人工拟合波结果峰值平台值为2.65;其二,对反应谱特征周期具有缩短效果,历史地震动较人工拟合波减小0.05～0.15s。产生上述影响效果,其可能与其高频成分地震动对固有周期较短的场地特点具有一定的共振影响有关。该结果可为建筑物抗震设防方面的研究提供参考。

Incorporating the one-dimensional seismic response analysis method of site soils,four historic earthquake observation records and one typical artificial fitting wave were selected for analysis,i.e.,the Loma Prieta M6.9 earthquake of 1989,the Northridge M6.6 earthquake of 1994,the Wenchuan M8.0 earthquake of 2008,the Minxian M6.6 earthquake of 2013,and the artificial fitting ground motion in Puyang city.The influences of input seismic waves with high and low frequency characteristics on the response spectra of the design ground motions were studied.The results showed that,as compared with the artificial fitting wave consisting mainly of low-frequency components,the input seismic waves consisting mainly of high frequency components had the effect of centralized amplification in a short period.The possible explanation could be that the input seismic waves with high frequency characteristics will cause a certain resonance effect on the sites having a short inherent period.The research results could provide some reference for the study of earthquake resistance building protection.