Comparison of steel moment resisting frame designed by elastic design and performance based plastic design method based on the inelastic response analysis

Presented in this paper is the comparison of a steel moment resisting frame designed by the Performance based Plastic design method and conventional elastic design method based on the seismic evaluation done by both nonlinear static (Push over Analysis) and nonlinear dynamic analysis (Time history analysis) under different ground motions. The Performance based Plastic design method uses pre-selected target drift and yield mechanisms as key performance criteria from the very start, eliminating or minimizing the need for lengthy iterations to arrive at the final design. The target drifts and the yield mechanism selected in the method are consistent with acceptable ductility and damage, for desirable response and ease of post earthquake damage inspection and reparability. The nonlinear static pushover analysis shows formation of hinges in columns of the frame designed using elastic design approach leading to collapse and formation of hinges in the beams and bottom of base columns of the Performance based Plastic design frame leading to increased Performance based Plastic design frame. Although these ground motions caused large displacements in the Performance based Plastic design frame as it was seen from the acceleration and displacement responses obtained from the nonlinear time history analysis, the structure did not lose stability. Study of hysteretic energy dissipation results reveals that the Performance based Plastic design method is superior to the elastic design method in terms of the optimum capacity utilization.