近场脉冲型地震对结构非弹性位移比谱的影响

Influence of Near-fault Pulse-type Ground Motions on Inelastic Displacement Ratio Spectra

将选择的746条各国强震记录按照我国建筑抗震设计规范中的规定进行场地分类.按照最新的识别近场强速度脉冲地震记录的定量方法,将选择的地震记录划分为中远地震、近震及近场强脉冲地震记录.利用这些强震记录,统计得到了近场强脉冲地震对应Ⅰ,Ⅱ,Ⅲ,Ⅳ四类场地的等延性位移比谱、等强度位移比谱的计算公式,并由此研究了场地条件及各种地震动参数对等延性位移比谱、等强度位移比谱的影响.结果表明:近场地震动的脉冲作用在中短周期段[0.3s,5s]对等延性位移比谱的影响较大,近场地震动的脉冲作用在中短周期段[0.5s,3s]对等强度位移比谱的影响较大且部分可达80%以上,场地条件对影响周期段的范围有重要影响;峰值地面速度与峰值地面加速度比(PGV/PGA)是影响近场地震动位移比谱最大的参数.

Based on the classified site criterion in current seismic design code of building （GB 50011- 2010） and quantitative classification scheme of near-fault ground motions proposed by Baker, the sites of 746 accelerograms from the strong-motion databank of some countries were classified as four site classes, and the 746 accelerograms were classified as far-field, near-fault and near-fault pulse-type ground motion accelerograms. Using the selected accelerograms, the empirical equations of near-fault pulse-type ground motion corresponding to four kinds of sites were presented for the inelastic displacement ratio spectra of constant ductility and constant yielding strength. The effects of site condition and different ground motion parameters on inelastic displacement ratio spectra were also evaluated. It is concluded that the influences of near-fault pulse-type ground motion on displacement ratio spectra of constant ductility and constant yielding strength are significant at periods [0.3 s,5 s] and periods [0.5 s,3 s] respectively, and site condition can control the period ranges of the above significant effect. PGV/PGA can provide the largest influence on displacement ratio spectra for near-field ground motions.