近断层速度脉冲的地震动特性研究

CHARACTERISTICS OF NEAR-FAULT GROUND MOTION CONTAINING VELOCITY PULSES

在搜集了大量近断层具有速度脉冲的记录后,对有速度脉冲和无速度脉冲的记录的反应谱和特征周期进行了对比,将近断层记录的反应谱与我国规范标准反应谱进行了比较,还将各次地震有速度脉冲记录的反应谱和特征周期与规范标准谱及规范给出的特征周期进行了比较.通过比较可知,在长周期段(大约在1.5s以后),有速度脉冲记录的反应谱值要比无速度脉冲记录的反应谱值大;计算特征周期时,对于近断层记录,T1和T2有后延的趋势,采用不固定频段的方法计算更加合理;无论是相对我国规范的Ⅰ类还是Ⅱ类场地,有速度脉冲记录的特征周期比规范中给出的值都要大,均在规范值的2倍以上.

Through collection of a large number of near-fault records containing velocity pulses, the response spectra and the characteristic periods of records containing no pulses are compared with those of records containing pulses. Response spectra of near-fault records are compared with standard spectra given by code; furthermore, the response spectra and the characteristic periods of each earthquake are compared with that given by the code. The result shows that at long periods （longer than 1.5 s）, the response spectrum of puls-containing records is bigger than the response spectrum of no pulse-containing records; when the characteristic period of near-fault records is calculated, the method that does not fix frequency is more reasonable because the T1 and T2 have a lagging tendency; regardless of the site Ⅰ and site Ⅱ, the characteristic period of pulse-containing records is over twice bigger than the characteristic period given by the code.