不同设防标准RC框架结构基于易损性分析的抗震性能评估

借助非线性动力时程分析,对严格按照规范Ⅶ、Ⅷ、Ⅸ度设计的5个三跨6层钢筋混凝土框架结构开展易损性分析,建立了基于峰值加速度的易损性曲线。从易损性的角度对不同设防标准RC框架结构的抗震性能做了定量评价,并探讨了设防标准对RC框架结构易损性的影响。分析表明,对应于设防小震、中震及大震水平的峰值加速度,结构“小震不坏”、“中震可修”和“大震不倒”的失效概率均在18%以内,可认为结构满足三水准的性态控制目标。随着结构设防标准的提高,其易损性随之降低,相同峰值加速度对应的各个破坏状态的超越概率均有所降低。此外,将框架结构的设防烈度提高1度,其“大震不倒”的失效概率会明显减小。而将框架结构的设防烈度降低1度,其“大震不倒”的失效概率会显著增加,最高可达4倍。

Seismic Performance Evaluation of RC Frames with Different Seismic Precautionary Intensity Based on Vulnerability Analysis

Five RC frames of three-span and six-story were designed with seismic precautionary intensities of Ⅶ、Ⅷ and Ⅸ degree. Vulnerability analysis of the five frames was performed by means of nonlinear dynamic time history analysis. Vulnerability curves based on peak ground acceleration were developed. Seismic performance of the five RC frames was quantitatively evaluated at the point of vulnerability. The effect of fortification criterion on vulnerability was discussed. It shows that, when meeting peak ground acceleration corresponding to small, moderate and large earthquake levels, the failure probabilities of "Undamaged under small earthquake", "Repairable under moderate earthquake" and "No-collapsing under large earthquake" are less than 18%, which satisfies the three level seismic performance targets. With the increase of seismic precautionary intensity, the exceedance probability of each damage state corresponding to a given peak ground acceleration is reduced. In addition, with increasing one degree of the seismic precautionary intensity, the failure probability of "No-collapsing under large earthquake" decreases. With reducing one degree of the seismic precautionary intensity, the failure probability of "No-collapsing under large earthquake" increases significantly, even up to four times.