一致风险谱作用下 RC 框架结构响应预测及其设计值确定

Seismic design based on uniform risk spectra (URS) can consider both seismic hazard and structural fragility, resulting in a uniform collapse risk of the structures in different regions. In order to determine the seismic design values of risk-targeted ground motions and the maximum inter-story drift ratio (MIDR) with uniform collapse risk, the ground motions were selected based on the URS of very rare earthquake and maximum considered earthquake. Then, the point of comparison method was used to predict the response (i. e., MIDR) of an 8-story 3-bay RC frame structure. Also, the incremental dynamic analysis (IDA) of the structure was conducted using the selected ground motions, and the seismic design value of MIDR was determined using the sample mean of structural response multiplied by the correction coefficient. Finally, the relationship between the seismic design value of the MIDR and its predicted value was studied, and the seismic design value of risk-targeted spectral acceleration was also determined on the basis of the IDA results. The results show that the MIDR of the RC frame structure designed based on the URS of very rare earthquake and maximum considered earthquake in the median IDA curve is 0. 010 and 0. 007, respectively, which not only meets the target collapse risk of 1% in 50 years, but also meets the requirements of CECS 392:2021 ‘Standard for anti-collapse design of building structures’ on MIDR (i. e., 1/50) of RC frame structures without collapse under earthquakes.