基于一致可靠度的地震动记录样本容量确定方法研究

Sample Size Determination for Strong Ground Motion Inputs Based on Reliability—Consistent Method

确定地震动输入样本容量是开展结构动力地震反应分析的重要环节,目前国内外关于地震动输入样本容量的讨论往往忽略或尚难以定量考虑结构地震反应估计的可靠度水平。以一实际钢筋混凝土框架结构为例,首先分析在大样本地震动作用下结构非线性地震反应的统计特征,研究估计结构地震反应时取样本最大值和平均值的差异,然后借助于假设检验分析结构地震反应的概率分布模型,给出基于一致可靠度的地震动样本容量确定方法,并对比分析单周期点、多周期点、谱值匹配调整地震动及人工合成地震动对样本容量需求的影响,为保证在小样本地震动输入下结构地震反应估计值满足给定可靠度和容许误差提供分析方法和判断依据。本文方法适应于定量确定不同结构类型和不同地震强度水平下的地震动样本容量需求,对建筑结构抗震性能评估及设计规范研究有一定意义。

Sample size determination for strong ground motion inputs is one of the most critical issues in carrying out nonlinear dynamic analyses.Most popular studies about ground motion sample size at home and abroad often ignore or barely consider the reliability of the structural seismic response estimation.In this paper,the reliability-consistent sample size determination method is presented to ensure a certain reliability of structural seismic response estimation.First,the statistical characteristics of structural nonlinear dynamic response under large ground motions sample for a typical reinforced concrete frame building are analyzed to discuss the difference between the maximum and mean values of structural responses.Then,based on the hypothesis testing of structural response probability distribution models,a sample size determination method for strong ground motion inputs based on the reliability-consistent method is proposed.In addition,the impacts of synthesized ground motions and single-period and multi-period spectral-matching methods for generating synthetic strong motions on the sample size demand are discussed to provide a determination method and estimation basis and ensure reliability and allowable error of structural response estimation using small sample size strong ground motions.The results show that distribution models of structural response highly accept the logarithmic extremum distribution and lognormal distribution hypotheses and completely reject the normal distribution hypothesis.This method is suitable for various types of building structures and ground motion intensities in determining ground motion sample size demand,which is very significant as regards seismic performance and the study of seismic design code.