TWO-STAGE MULTI-DIMENSIONAL PUSHOVER ANALYSIS FOR BI-DIRECTIONAL EARTHQUAKE EXCITATIONS

The nonlinear relationship between force and displacement of a structure obtained by modal pushover analysis is only suitable for the response of the corresponding structural mode, and it can not be used to analyze the elastic-plastic development process of the structure. Thus, for the asymmetric structures subjected to bi-directional earthquake excitations, a two-stage multi-dimensional pushover analysis procedure is presented. The first stage: the modal multi-dimensional pushover analysis procedure is used to obtain the responses of structures. The second stage: the new pushover load pattern is established according to combined structural modes and the second time multi-dimensional pushover analysis is implemented, in which the nonlinear force-displacement relationship of structures is analyzed. An example analysis shows that: 1) the procedure presented in the paper may be used as an effective method to estimate the distribution of deformation response along the structural floors. 2) With the increases of nonlinear responses and storey numbers, the deviations of estimation increase gradually. 3) The multi-dimensional pushover, based on the combined modal pushover load pattern, is suitable for analyzing the elastic-plastic development process of structures.