地震动滞回能量谱衰减规律研究

Study on attenuation of hysteretic energy spectra of strong ground motion

本文选用美国西部California州15次较大地震中的266条强地震动记录,利用衰减关系建立了滞回能量谱,分析了场地条件、延性系数、震级及距离等参数对滞回能量谱的影响。研究发现,场地条件对滞回能量谱影响很大,随着场地变软,滞回能量谱变大,与A+B类场地相比,C类场地的滞回能量谱平均要高出70%左右,D类场地则要高出170%左右。随着延性系数的增大,滞回能量谱有增大的趋势,尤其是当延性系数由2变到4或6时更为明显,但当延性系数增加到一定程度时,滞回能量谱的差别不大,延性系数为4和6时的滞回能量谱差别不大,甚至在周期较大时,延性系数为6的滞回能量谱反而小于延性系数为4时的滞回能量谱。另外,研究结果表明,大的震级和小的距离对结构产生比较大的滞回能量需求。利用本文结果,可以估计未来地震中结构物所遭受滞回能量的大小。

Based on 266 strong ground motion records from 15 significant earthquakes in California of America, an attenuation relationship was developed for ground motion hysteretic spectra with earthquake magnitude, source-to-site distance, and site class. The effects of parameters such as magnitude, site class and ductility factor on the hysteretic spectra constructed from the attenuation relationship were discussed in the paper. The results show that the site class has a significant effect on hysteretic energy spectra. The increase of hysteretic energy spectra from site A+B to sites C and D is about 70% and 170% respectively. With the increase of ductility factor, the hysteretic energy spectra have an increase trend, especially from 2 to 4 or 6, but there is little difference between the hysteretic energy spectra for ductility factor 4 and 6. On the contrary, the hysteretic energy spectra for ductility factor 4 are larger than that for ductility factor 6 in long period range. Also, the results show that larger magnitude and shorter distance contribute more to hysteretic energy demand of structures. The hysteretic energy demand of structures in future earthquake could be evaluated according to the results of the paper.