Maximum displacement profiles for the performance based seismic design of plane steel moment resisting frames

New relations to estimate maximum seismic displacement profiles of plane steel moment resisting frames are proposed. These expressions associate maximum floor displacements with local member deformation seismic demands and are based on statistical analysis of the results of several hundred nonlinear dynamic analyses of steel frames. The influence of specific parameters, such as the number of stories, the number of bays, the joint capacity design factor and the level of inelastic deformation induced by the seismic excitation, is studied in detail. It is concluded that the main structural characteristic that affects the shape of the displacement pattern is the number of stories. Furthermore, the present study reveals that a differentiation between the profile of a frame in the elastic and the inelastic range of response is necessary. A comparison between the proposed displacement patterns and other existing ones is also made to demonstrate the merits of the former.