a shear-based adaptive pushover procedure for momentresisting frames

The effects of higher modes are neglected in conventional pushover analysis procedures. among the improved pushover methods, the adaptive pushover procedures are attractive for their multi-mode capability. in such procedures, the dynamic characteristics of buildings are updated in each stage of analysis consistent with the extent of the non-linear action throughout the structure. in this paper an adaptive pushover procedure is introduced that works with inter-story shear forces. it is compared with the conventional adaptive pushover methods where story accelerations or displacements are the bases of analysis. in the proposed method, the inter-story shears are calculated and updated based on the current dynamic characteristics of structure at each analysis step. they are then converted to the equivalent lateral forces for pushover analysis. through using a correction factor based on the fundamental period of the building, a procedure is also developed for modifying the story drifts. comparison with the average results of exact nonlinear dynamic analysis of a number of buildings under several earthquakes shows accuracy similar to the most precise procedure within the available conventional adaptive pushover methods. for the comparative analysis, 5, 10 and 15-story buildings and seven ground motions are utilized. moreover, the proposed method is practically more adaptable to the current commercial softwares