基于推覆分析的结构倒塌安全储备系数

DETERMINATION OF STRUCTURAL COLLAPSE MARGIN RATIO USING PUSHOVER ANALYSIS

基于增量动力分析(英文简称IDA)的倒塌安全储备系数(英文简称CMR)计算是ATC-63报告建议的方法,该方法需要做大量的非线性时程分析,计算非常耗时且效率不高,不适于结构方案设计阶段针对倒塌安全储备能力的快速评估。该文提出了基于推覆静力分析的倒塌安全储备系数(CMR)的实用计算方法,该方法中以改进的Park-Ang损伤模型作为结构整体倒塌判别准则,倒塌性能点则是通过推覆分析得到的能力曲线,并结合由各个地震动的反应谱以及Nassar-Krawinkler塑性谱生成相应的塑性需求曲线来确定。该方法结合了ATC-63报告中计算思路和推覆分析的特点,考虑了所选地震动对倒塌性能点的差异性,计算效率大大提高,且计算结果偏于保守地合理,上述特点通过一8层钢筋混凝土框架结构的算例得以证明。

The incremental dynamic analysis(IDA) method suggested in ATC-63 report requires a large amount of time history analyses in determining a structural collapse margin ratio(CMR). It is time-consuming and computationally inefficient, not suitable for a quick assessment on collapse margin during the scheme design stage of structures. A practical method proposed herein to evaluate CMR is on the basis of the pushover analysis procedures, in which the collapse performance points of all selected strong ground motions are determined by the improved Park-Ang global damage model and the combination of the capacity curve obtained from the pushover analysis and the demand curves generated from the response spectra of the motions of concern and Nassar-Krawinkler inelastic spectrum. The proposed method has incorporated the concepts addressed in ATC-63report and the characteristics of the pushover analysis, as well the consideration of variation in the collapse performance point caused by different motions. The computational efficiency has been substantially improved and reasonably conservative. These have been validated through an 8-story reinforced concrete frame structure.