assessment of conventional nonlinear static procedures with fema load distributions and modal pushover analysis for high-rise buildings

the nonlinear static pushover analysis technique is mostly used in the performance-based design of structures and it is favored over nonlinear response history analysis. however, the pushover analysis with fema load distributions losses its accuracy in estimating seismic responses of long period structures when higher mode effects are important. some procedures have been offered to consider this effect. fema and modal pushover analysis (mpa) are addressed in the current study and compared with inelastic response history analysis. these procedures are applied to medium high-rise (10 and 15 storey) and high-rise (20 and 30 storey) frames efficiency and limitations of them are elaborated. mpa procedure present significant advantage over fema load distributions in predicting storey drifts, but the both are thoroughly unsuccessful to predict hinge plastic rotations with acceptable accuracy. it is demonstrated that the seismic demands determined with mpa procedure will be unsatisfactory in nonlinear systems subjected to individual ground motions which inelastic sdf systems related to significant modes of the buildings respond beyond the elastic limit. therefore, it’s inevitable to avoid evaluating seismic demands of the buildings based on individual ground motion with mpa procedure.