Seismic Retrofit Decision-Making based on Life Cycle Cost Criteria

The life-cycle cost can be regarded as a benchmark variable in decision making problems involving the seismic retrofit and upgrading of existing structures. A methodology is presented which takes into account both the uncertainty in the occurrence of future earthquake events and also the deterioration of the structure as a result of a series of earthquake events. In order to satisfy life safety conditions, the probability of exceeding the limit state of collapse is constrained to be smaller than an allowable threshold. The presented methodology is applied to retrofit decision-making for a set of viable upgrade options for upgrading of an existing RC building. The upgrade solutions considered include (a) reinforcing with fiber reinforced polymers (FRP), (b) addition of buckling restrained axial dampers (BRAD), (c) reinforcing with steel angles and steel ribbons (the CAM system), (d) applying both the FRP reinforcement and the BRAD, (e) applying both the CAM solution and the BRAD.