考虑结构局部反应特征的时程分析法输入地震波研究

A Study on the earthquake input for time-history analysis based on the local response characteristics of structures

时程分析法在实用中多采用"3+1"的小样本容量地震波输入方式,该选波方案一般依据基底剪力、顶点位移等结构整体反应指标而取得。为提高时程分析法对构件局部地震变形需求的控制能力,以按我国规范设计的典型钢筋混凝土框架为算例,在OpenSees分析平台上,分别进行了30条地震波的大样本和以"3+1"选波方案为例的小样本地震波在罕遇烈度下的非线性时程反应分析。在对地震反应进行统计回归分析后,将小样本分析所得各反应量的均值、均值加1倍标准差等统计特征值与大样本统计结果进行比较,着重考察框架的塑性铰分布、构件转角延性等局部反应。研究结果表明,"3+1"分析方法所得的框架整体变形能较好地与大样本分析结果相符,但多数构件端部转角延性的"3+1"分析均值偏小,建议增加小样本分析的地震波数量。

‘3＋1＇ is the mall sample size of earthquake wave input method commonly adopted in practical time-history analysis. It is generally obtained base on the global structural responses, such as base shear and top displacement. The capability of time-history analysis for controlling the local structural seismic responses is studied. A typical reinforced concrete frame designed according to the Chinese building codes is chosen as the example. Based on the OpenSees framework, a series of nonlinear time-history analyses under a large sample of thirty rare earthquake waves and a small sample of ＂3＋1＂ rare earthquake waves are performed, respectively. Through the statistical calculation of seismic responses, the statistical characteristics, such as mean value and mean plus standard deviation, obtained from the ＂3＋1＂ analysis are compared with the corresponding values from the large sample analysis. Local responses of the frame, namely the plastic hinge distribution and the rotation ductility of beams and columns, are analyzed. The results indicate that the global response from the ＂3＋1＂ analysis matches well with the corresponding results of the large sample analysis, while most of the mean rotation ductility of members from the ＂3＋1＂ method are smaller, and it is suggested that sample size should be increased.