中国大陆地区建筑结构一致倒塌风险的设计地震动研究

Study on design ground motion for uniform collapse risk of building structures in China's Mainland

基于一致倒塌风险的抗震设计可使不同地区的建筑物在一定时期内达到倒塌风险一致。为了对中国大陆地区建筑结构基于一致倒塌风险的设计地震动的确定进行研究,介绍了一致风险地震动的基本概念及通过设计因子法获取一致风险地震动的原理,并对中国大陆地区一般建筑结构基于一致倒塌风险的地震动计算时采用的结构易损性标准差、目标倒塌风险和设计地震动对应的倒塌概率的合理取值进行分析,结果表明,以一致危险性地震动设防的中国大陆不同地区的一般建筑结构不能达到一致倒塌风险。基于给定的输入参数,使用设计因子法得到了中国大陆基于一致倒塌风险的地震动与当前地震动参数区划图中50年超越概率10%地震动的比值(称为设计因子)的分布,并对不同的输入参数对设计因子的影响进行了分析,发现设计因子与地震动参数有很强的相关性,进而给出了适用于中国大陆的地震反应谱设计因子与地震动参数的拟合式。通过对全国不同烈度分区的算例表明,使用该拟合式得到的一致风险反应谱可以使不同地区和不同周期的结构获得一致的倒塌概率。

Seismic design based on a uniform risk of collapse can be achieved over a period of time for buildings in different areas. The purpose of this paper is to study the determination of design ground motion of building structures in Chinese mainland area based on consistent collapse risk. The basic concept of consistent risk ground motion and the principle of obtaining consistent risk ground motion by design factor method are introduced. The reasonable values of the standard deviation of structural fragility, the target collapse risk and the collapse probability corresponding to the design ground motion used in the calculation of consistent collapse risk-based ground shaking for general buildings in China's Mainland are discussed. The results show that the general buildings in different regions of China's Mainland, which are fortified with uniform hazard ground motion, do not achieve a consistent risk of collapse. Based on the input parameters given in this paper, the distribution of the ratio of ground motion based on consistent collapse risk to the ground motion with a 50-year exceedance probability of 10% in current ground motion parameter zoning map for China's Mainland(referred to as the design factor) is obtained using the design factor method, and the effects of different input parameters on the design factor are analyzed. A strong correlation between the design factor and the ground motion shape parameter is found, which leads to a fitted equation for the design factor of the ground shaking response spectrum and the ground shaking shape parameter applicable to China's Mainland. The numerical examples of different intensity zones in China show that the uniform risk response spectra obtained using the proposed fitted equation can lead to uniform collapse risk of structures in different regions and at different periods.