基于强震动数据的等强度延性谱影响因素分析

Analysis of Influencing Factors on the Constant-strength Ductility Spectra based on the Strong Ground Motions

基于5500余条峰值加速度大于50 gal的水平向地震动数据,采用双线性模型计算了单自由度体系弹塑性反应,从地震信息参数和地震动参数2方面分析了影响等强度延性谱的因素。首先在场地分类的基础上按震中距和震级大小将地震动分组,分析了震中距远近和震级大小对等强度延性谱的影响;然后在地震动参数方面分析了反映幅值、频谱以及持时的峰值速度(PGV)、有效峰值加速度(EPA)以及Bolt持时等代表参数,并且根据PGV,EPA和Bolt持时的大小分组,分析了其对等强度延性谱的影响,结果表明:①在大部分周期内,各组等强度延性谱值差异较大,在各个场地内震中距和震级较大时,对应的延性谱值较大;②分组效果最好的地震动参数为PGV,其次是Bolt持时,当根据EPA分组时,分组结果最不理想。

To study the effect of different factors on the constant-strength ductility spectra,based on more than 5500 horizontal ground motion data with peak ground acceleration greater than 50 gal,the elastoplastic response of single degree of freedom system(SDOF)is calculated by bilinear model,and the factors affecting the constant-strength ductility spectra are analyzed mainly from the aspects of seismic information parameters and ground motion parameters.First,in the analysis of seismic information parameters,ground motions are grouped according to the epicenter distance and magnitude on the basis of site classification,and the effects of epicenter distance and magnitude on the constant-strength ductility spectra are analyzed.Second,in terms of ground motion parameters,the representative parameters reflecting amplitude,frequency spectrum and duration,such as peak ground velocity(PGV),effective peak acceleration(EPA)and Bolt duration,are analyzed,and their effects on constant-strength ductility spectra are analyzed by grouping them according to the magnitude of PGV,EPA and Bolt duration.The results show that:①In most of the periods,there is a greater difference in the constant-strength ductility spectra of each group,and when the epicenter distance and magnitude are larger in each site,the corresponding ductility spectrum values are larger.②The best grouping effect is PGV,followed by Bolt duration.When grouped according to EPA,the grouping result is the most unsatisfactory.Therefore,when establishing constant-strength ductility spectra based on the strong ground motion records,it is necessary to consider the comprehensive effects of epicenter distance,magnitude,PGV and other parameters.