概率地震需求分析的简化方法研究

概率地震需求分析的主要工作是获得不同地震动强度水平下结构地震需求的概率分布。本文采用与结构基本周期对应的线弹性加速度反应谱Sa作为地震动强度指标，结构的位移延性为地震需求指标。通过对大量单自由度体系非线性时程分析结果的统计及回归分析，获得了在给定结构强度折减系数R、周期T的条件下，延性需求的均值和标准差的拟合公式，并建立了概率的等R延性需求谱。基于该谱，提出了简化的概率地震需求分析方法。算例分析表明，建议方法的计算结果与增量动力分析方法的计算结果接近，但计算量却大为减少。

A Simplified Probabilistic Seismic Demand Analysis Method

The main work of probabilistic seismic demand analysis is to obtain the probabilistic distribution of structural seismic demand at different intensity of ground motions. In this paper, linear-elastic response spectra acceleration S. at the structural fundamental period is treated as the intensity index of ground motions, and structural displacement ductility is treated as seismic demand index. Using the results of comprehensive dynamic analyses, empirical expressions based on regression analysis are derived for the mean and standard deviation of ductility demands conditional on given natural period and strength reduction factor R. Then led to the construction of probabilistic constant-R ductility demand spectra. Based on the spectra, a simplified procedure is proposed for probabilistic seismic demand analysis. In the end, an illustrative example is presented. The results of probabilistie seismic demand by proposed procedure are closed to that by incremental dynamic analysis, but the computation efforts are largely saved.