反应谱特征周期分析

Analysis of characteristic period of acceleration response spectrum

特征周期是反应谱的重要参数，《建筑抗震设计规范》（GB 50011-2010）规定特征周期为设计反应谱曲线下降段起点对应的周期．根据概率法选取28条完整地震记录，利用自编Fortran程序进行地震影响系数的计算，得到反应谱曲线．通过概率法计算不同面积百分比下的特征周期；按美国ATC3-06规范确定有效峰值速度和有效峰值加速度，计算特征周期，进行反应谱特征周期的统计分析．统计表明：特征周期随面积百分比减小逐渐增大．特征周期与反应谱曲线形状有关，当平台段末端的反应谱曲线波动时，特征周期值会有明显变化．概率法求特征周期当面积百分比在90％～97％时，特征周期取值比较稳定，和平均值接近．概率法计算得到的特征周期平均值与美国ATC3-06规范计算得到的特征周期平均值相差不大，有较好的参考价值．

As defined in Code for Seismic Design of Buildings （GB 50011-2010）, the characteristic period is the starting point of descending stage in acceleration response, which is considered as an important parameter of acceleration response spectrum. 28 complete ground motion records are selected in line with the means of probabilistic method, and horizontal earthquake influence coefficient is calculated hy the self-complied Fortran program, on which the response spectrum curves are given. The characteristic period at different area percentage is calculated by probabilistic method and the effective peak velocity, and effective peak acceleration for calculating characteristic period is determined in accordance to ATC 3-06, under which statistical analysis of characteristic periods of response spectrum are made. Results indicate that the characteristic period goes larger with the decrease of the area percentage. The characteristic period is relevant to the shape of acceleration response spectrum curve. And as the end platform of acceleration response spectrum curve fluctuated, the characteristic period varies obviously. The characteristic period that is calculated by probabilistic method is relatively stable and is close to the average, when the area percentage at 90 %-97 %. The average of characteristic period calculated by probabilistic method does not have much difference from that calculated by ATC 3-06, which has a good referenced value.