Cost-benefit analysis of seismic-isolated structures with viscous damper based on loss estimation

This paper presents a methodology to utilise performance-based seismic design procedure for evaluating isolated structures with or without viscous dampers (VD) considering cost-benefit analysis. A non-linear four-story archetype of conventional steel structure, a lead-rubber-bearing isolated structure and a natural rubber-bearing isolated structure with the linear VD are compared with each other under far-field (FF) and near-field (NF) ground motions. Also, loss parameters, such as expected annualised loss, expected annualised repair time, expected annualised fatalities and expected annualised injuries based on loss estimation process, are utilised for evaluating the structures. Sensitivity analysis is used to study the effect of modelling uncertainty variations in the loss estimation process. It has been found that the effectivity of supplemental damping for low damping isolated structures increases in the NF comparing with the FF ground motions. Finally, the cost-benefit analysis is done to calculate payback period of investment for additional cost of the isolation system with or without the supplemental damping. The advantage of loss estimation is an improved method to evaluate the effectiveness of the isolation system in terms of loss parameters that are useful in the cost-benefit studies and for determining rational insurance premiums.