Performance evaluation of damaged steel frame buildings subjected to seismic loads

This paper presents a systematic evaluation approach that allows the design professional to estimate the performance of damaged buildings subjected to sets of ground motions representing different hazard levels. The performance of damaged buildings for a future seismic event prior to repair and/or rehabilitation was evaluated using an elastic model and stiffness of the structure. The linear static model using the damaged state of brittle fractured connections in steel moment resisting frame buildings provides a reasonable estimation of the interstory drift of the damaged buildings when compared to nonlinear time history analysis. Then, this result was incorporated in a reliability-based procedure that provides a degree of confidence that a building before and after the damage will exceed the given performance levels. Finally, examples of confidence level calculations are presented. The results showed that the linear static model and the performance evaluation procedure are very useful and allow the design professional to determine the level of safety of damaged buildings.