极罕遇地震作用下建筑结构一致风险抗倒塌设计方法研究

结合当前国际上以“抗倒塌”为目标进行地震动参数区划和以“一致倒塌风险”为设防目标进行结构抗震设计的发展趋势，针对我国现行建筑抗震设计规范体系中抗倒塌能力评估的局限性，建议了四种一致风险抗倒塌设计方法，详细介绍了四种方法的评价指标与计算过程。考虑极罕遇地震作用，基于极罕遇地震一致风险谱对地震动记录进行了挑选与调幅。以RC框-剪结构作为典型案例，采用四种抗倒塌设计方法进行验算，结果表明：同时考虑地震危险性与结构不确定性影响的全概率方法验算未通过，其余验算方法均通过，这说明了忽略结构所在场地危险性影响会造成结构倒塌性能评估的不准确性，未考虑结构体系多种不确定性影响会高估结构的抗倒塌性能，因此有必要推行“一致风险”的结构设计理念。

Study on uniform collapse risk design methods for building structures under very rare earthquakes

It is a global trend to take the prevention of collapse of building structures as the fortification target for the zonation of earthquake ground motion parameters and conduct seismic design with a target of uniform collapse risk of building structures. In line with the global trend, four collapse-resistant design methods based on uniform collapse risk were presented to overcome the limitations of the collapse-resistant design method in the current code of seismic design of building structures in China. The evaluation indicators and calculation procedures of the four methods were presented in detail. Very rare earthquakes (VRE) were considered, and the selection and linearly scaling method of ground motions based on the uniform risk spectra of VRE were proposed. Taking RC frame-shear wall structures as a typical case, the four collapse-resistant design methods were applied and compared. The results show that the total probability collapse resistant design method considering seismic hazard and structural uncertainties fails in the checking computations, while the other collapse resistant design methods pass. It is illustrated that neglecting the influence of seismic hazard leads to inaccurate evaluation of collapse-resistant performance of structures, while ignoring the impact of multiple uncertainties in the structural system leads to overestimation of the collapse resistance. Therefore, the concept of ‘uniform risk’ should be implemented in structural seismic design.