反应谱特征周期的统计分析

特征周期是反应谱的重要参数,是工程抗震设计的关键参数,但物理意义不明确、涉及因素多、结果离散,研究成果相对较少.从反应谱的本质出发,提出了反应谱特征周期的概率法.搜集近期1491条地震记录,采用概率法（97%）和美国FEMA-450（2003）法,以中国抗震规范特征周期分类为依据,研究了反应谱特征周期的统计规律.研究表明：概率法从面积比确定特征周期,力学概念明确,确定标准统一,与美国FEMA-450（2003）法有较好的一致性;近期地震波的特征周期分布特征表明,抗震规范规定的不同场地、不同地震分组的特征周期区段,地震记录数量不同,长周期效应不容忽视.特征周期与震级、场地类别和震中距的关系复杂且离散,特征周期呈区间分布规律,分布区间值较大,区间内部定量关系仍较难确定.特征周期与震级、场地类别和震中距的相关性不明显,反应谱特征周期按场地类别、震中距（地震分组）确定,存在不确定的风险,美国抗震规范以反应谱参数直接确定特征周期的方法,抗震规范修订时值得借鉴.

Empirical Statistical Analysis of Characteristic Period of Acceleration Response Spectrum

The characteristic period is an important engineering parameter of acceleration response spectrum, but there are many problem such as illegible physical concept, involving many factors,discrete result distribution and less research inpossession. The paper proposes a probabilistic method according to the essence of acceleration response spectrum. The characteristic period was calculated by area ratio of acceleration response spectrum at the point of the characteristic period. Therefore, the characteristic period has distinct mechanics significance. The statistical analysis rules of characteristic period are derived from 1491 recent ground motion records by means of probabilistic method and FEMA-450 method. The results indicate that probabilistic method and FEMA-450 method are good in coherence. The different amounts distribute in different characteristic period range of site and design earthquake group in seismic code of China. And consequently, ＇the long period dynamic effects should not be ignored. The characteristic period covers a large range and disperses. There are no obviously coherence among characteristic period, magnitude of earthquake, site categories and site-source distance. The characteristic period which is determined by site and design earthquake group has more indeterminacy. Thus the suggestion which the characteristic period should be determined by parameters of acceleration response spectrum similar to USA code is proposed when the version of the former ＂code for seismic design of buildings GB 50011-2001＂ in China is revised.