四川地区抗弯钢框架结构基于性态的地震易损性分析

Performance-based Seismic Vulnerability Analysis of Moment-resisting Steel Frames in Sichuan Region

为研究四川地区抗弯钢框架结构在设防烈度提高情况下的地震易损性能,按上一代抗震规范设计了5层、10层、15层在四川地区建造的3个抗弯钢框架结构,考虑了钢材强度、弹性模量、层高及跨度等主要参数不确定性因素的影响,利用拉丁超立方抽样方法建立了3组40个抗弯钢框架结构样本。通过选取汶川地震中四川境内实测的40条地震记录反映地震输入的不确定性,并分别同3组40个抗弯钢框架结构样本进行随机组合。采用非线性时程分析方法获得3组40对抗弯钢框架结构-地震动样本集的最大层间位移角响应,结合已定义的钢框架结构的性态水平,建立了以结构第1周期谱加速度SA表征的抗弯钢框架结构在不同性态水平下的地震易损性曲线,评估了原地震水准及地震水准提高情况下钢框架结构的抗震性能。此外,还建立了对应于现行抗震规范规定的多遇及罕遇地震水准结构层间位移角限值水平下抗弯钢框架结构的地震易损性曲线,并进行了抗震性能评估,为今后震害预测提供参考。

To investigate the seismic vulnerability of moment-resisting steel frame in Sichuan region under the upgrade of seismic fortification intensity,a series of five-,ten-,and fifteen-story moment resisting steel frames located in Sichuan region were designed according to former seismic code.The uncertainties including steel strength,elastic module of steel,span,and story height were considered,and a total of 40 steel frame specimens for each group were developed on the basis of the Latin hypercubic sampling approach.A set of 40 earthquake ground motions recorded in Sichuan region from Wenchuan earthquake was chosen to consider the uncertainty of ground motions,and then combined randomly with 40 steel frame specimens.The maximum inter-story drifts of 40 steel frame specimens were obtained on the basis of nonlinear time history analysis method.Combined with the structural performance levels of steel frame,the seismic vulnerability curves of steel frames at the different structural performance level representing by spectral acceleration at the first period were proposed,and the seismic behavior of steel frames was evaluated.In addition,the seismic vulnerability curves of steel frames at given inter-story drift limit value according to current seismic code were constructed,and the seismic behavior of steel frames was also evaluated,which could provide some useful references for future seismic damage prediction.