地震作用下钢框架结构抗竖向连续倒塌可靠度分析

Vertical Anti-progressive Collapse Reliability Analysis of Steel Frame Under Seismic Action

为了对偶然荷载作用下结构的抗连续性倒塌进行可靠度研究,采用OpenSEES软件建立钢框架连续倒塌分析数值模型,考虑到钢框架结构材料和荷载的不确定性,使用拉丁超立方抽样方法生成钢框架结构随机样本,并采用随机Pushover算法对钢框架结构进行分析,计算得到X、Y两个方向不同地震水平下各钢柱承载能力及变形能力的可靠度指标,根据抗震可靠度相关理论确定目标可靠度指标,通过比较各柱的可靠度指标和目标可靠度,对结构在地震作用下最可能失效构件进行识别。基于所识别的最可能失效构件,结合所生成的100组钢框架结构随机样本,采用拆除构件法对钢框架结构在单柱失效和多柱失效等工况下进行抗连续倒塌IDA分析,得到随机IDA分析曲线。通过结构连续倒塌极限状态方程,计算得到损伤结构发生连续倒塌的概率及连续倒塌条件可靠度指标。采用基于风险的结构连续倒塌概率表达式,分析地震作用下钢框架结构发生局部破坏后的连续倒塌全概率可靠度,为准确评价钢框架结构在地震作用下的抗连续倒塌能力提供依据。

In order to study the reliability of anti-progressive collapse of structures under accidental loads,the numerical model of steel frame progressive collapse analysis was established by OpenSees software.Considering the uncertainty of materials and loads of steel frames,Latin hypercube sampling method was used to generate random samples of steel frames,and random Pushover algorithm was used to analyze steel frames.The reliability indexes of load capacity and deformation capacity of each steel column under different seismic action levels in X and Y directions were calculated,and the target reliability indexes were determined according to the seismic reliability theory.By comparing the reliability indexes and target reliability of each column,the most probable failure members of the structure under seismic action were identified.Based on the identified most probable failure members and 100 groups of steel frame structure random samples,IDA analysis of steel frame structures under various working conditions such as single-column failure and multi-column failure was carried out by the alternative path method,and the random IDA analysis curves were obtained.Through the limit state equation of progressive collapse,the probability of progressive collapse of damaged structures and the conditional reliability index of progressive collapse were calculated.The full probability reliability of progressive collapse of steel frame structure after local damage under seismic action was analyzed through the probability expression of structure progressive collapse at risk,which can provide a basis for accurately evaluating the anti-progressive collapse ability of steel frame structure under seismic action.