Outrigger Braced System Placement Effect on Seismic Collapse Probability of Tall Buildings

The placement of bracing can affect the seismic response and energy balance in the outrigger braced systems. In this study, it is attempted to investigate the effect of placement optimization of outrigger braced system on the seismic response of a 50-story structure. IDA curves are used to investigate the seismic responses. Sa and Sd are considered as intensity measure (IM) Parameters. Maximum story drift and inelastic strain energy considered as Engineering Demand Parameters (EDP). At first, IDA curves are derived based on maximum story drift in the structures. When the performance level is determined, their fragility curves are derived and compared. In the next step, the energy balance is investigated in the structures and the strain energy parameter is selected as EDP, which the damage level is determined in accordance with. Fragility curves are plotted and the results are assessed using the plastic strain energy. The results show that the placement optimization of outrigger braced system improves all structural parameters and reduces the collapse probability. Moreover, the fragility curves obtained from plastic strain energy as EDP are quite similar to the fragility curve derived from the selection of story drift as EDB.