地面运动强度指标对RC桥墩地震需求的影响

Influence of the selection of strong-motions intensity measures on the seismic demands for RC bridge columns

强地面运动指标(IM)的选择对桥梁结构工程需求参数(EDP)的概率估计影响很大。文章分别采用峰值地面加速度PGA和峰值地面速度PGV作为IM,选择实际地震波并进行合理的调值,对一座RC桥墩进行非线性动力时程分析;结果表明,对于中等周期的桥墩结构,以PGA作为IM计算的EDP概率估计值离散度明显更大。因此应根据所分析结构的周期范围,选择不同的IM,通过合理的调值对EDP进行概率估计。

There is a significant influence of the selection of earthquake strong-motions intensity measures on the probabilistic evaluation of engineering demand parameters（EDP）. A series of nonlinear dynamic time history analyses using real accelerograms with reasonable scaling are made of a RC bridge column when peak ground acceleration （PGA） and peak ground velocity （PGV） are selected as intensity measures（IMs）. The analytic results reveal that the probabilistic estimators of the EDPs which are gained using PGA as an IM generally have larger dispersions as the bridge columns with middle periods are considered. It is noted that the PSDM can be developed accurately and efficiently on the basis of the periods of structures analyzed by selecting different IMs and reasonable sealing to estimate different EDPs.