基于MPA考虑土-结构相互作用的RC框架抗震性能的研究

Research on method of MPA with considering SSI in evaluating seismic performance of RC frame

采用ATC-40推荐的土集中参数模型,将土-结构相互作用引入MPA分析中,并考虑重力荷载下的P-Δ效应,研究RC框架的抗震性能。利用SAP2000对一10层RC框架分别进行考虑SSI的MPA分析、Accel和Mode1侧向加载模式的Pushover分析以及非线性动力时程分析,进行不同场地类型下结构抗震性能的评估。多遇地震结果表明:考虑SSI的MPA分析最接近时程分析的结果,顶点位移和层间位移角误差分别在10%和20%以内。罕遇地震结果表明:考虑SSI效应后,常规Pushover分析的误差较大,已不能满足精度要求;而考虑SSI的MPA在一定程度上能评估结构的抗震性能。若结构未倒塌,考虑SSI的MPA能较好地估计塑性铰的分布;若结构倒塌,考虑SSI的MPA得到的梁铰分布与时程分析较一致,然而低估了底层柱铰的塑性变形,但不影响对结构薄弱层的判断。

This paper used the lumped parameter model of soil recommended by ATC-40 to consider soil-structure interaction into MPA,meanwhile including the P-Δ effect under gravity load. A 10-story RC frame was set up by SAP2000 to conduct SSI research respectively through MPA, Pushover analysis with loading mode Accel or Mode1 and nonlinear dynamic time history analysis, evaluating the seismic performance of structure under different types of ground. Research under frequent earthquakes shows that the results of MPA are most close to the results of time history analysis, with errors of roof displacement are all within 10% and errors of story drift are all within 20%. Research under severe earthquakes shows that with considering SSI, the errors of Pushover analysis with Accel or Mode1 are extremely large, not meeting precision requirement; While MPA with considering SSI can evaluate the seismic performance of the structure to a certain extent. If the structure is not collapsed, MPA can estimate the distribution of plastic hinge; if the structure collapsed, the beam hinges distribution of MPA are similar to time history analysis. MPA underestimate the plastic deformation of bottom column hinge, but it does not affect the judgment of the weak layer.