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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.

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Among important issues in progressive collapse behavior of a building is tracking down the type and location of the damaged elements. This paper deals with identifying the distribution of collapse from the first element to the entire building due to earthquake loads. Here, 3D collapse propagations in symmetric and asymmetric reinforced concrete buildings are compared using nonlinear time history analyses. The variables of such analyses are earthquake load intensity and the level of in plan one directional mass eccentricity. Results show that collapse distribution is dependent on the degree of asymmetry in building. Some patterns to predict progressive collapse scenarios in similar symmetric and asymmetric buildings are also determined. One main pattern shows that the propagation of collapse is horizontal through the stories, but not vertical through the height of the buildings. Spread of the collapse is independent of the earthquake records also according to the results, damage concentration is larger in places with larger mass concentration.