Design of Low-Rise Controlled Rocking Braced Frames for Life Cycle Costs

Controlled rocking braced frames (CRBFs) are being developed as a seismic force resisting system with promising structural performance and minimal residual drift. Allowing CRBFs to uplift and rock while controlling their response with energy dissipation devices and post-tensioning strands can reduce structural losses and provide self-centring behaviour to avoid residual drifts. Previous studies have shown that even CRBFs designed with a large response modification factor (R) have high drift capacity and low collapse probability. To complement CRBFs’ excellent structural performance, it is also necessary to consider the demands on nonstructural components, which may account for more than 80% of the building’s investment. In this study, three- and six-story CRBFs with different R factors are designed and loss assessment analysis is performed. The results show that less than 30% of losses were due to structural damage, including complete building loss due to collapse or excessive residual drift. Conversely, acceleration-sensitive structural components accounted for a substantial percentage of the damage in buildings with CRBFs. In all cases, the total annualized repair cost was small relative to the initial construction cost of the building.