On the optimal performance-based seismic design objective for steel moment resisting frames based on life cycle cost

Abstract

The present study attempts to propose an optimum performance objective in the performance-based design method based on life cycle cost. For this purpose, the optimum hazard level which corresponds to the Life Safety performance level is explored in order to minimize the total cost of standard commercial office buildings. Furthermore, the effect of some parameters such as building depreciation over time, building lifetime, and monetary discounting rate on the optimal seismic hazard level is evaluated. The uncertainties involved in seismic loss assessment are considered according to the FEMA-P-58 methodology. To achieve the objectives of this study, three buildings with steel moment frame structures having 5, 10, and 15 stories are investigated. The buildings are optimally designed at different seismic hazard levels with a performance-based approach and then evaluated for the probabilistic life cycle cost. Among the five designs with different design objectives for each building, the design with the minimum total cost is chosen as the optimal design and the corresponding seismic hazard level is presented as the optimal hazard level. The results show that an increase of up to 25.1% in initial structural cost by selecting the optimal hazard level leads to a decrease of up to 57.7% and 16% in life cycle cost and total cost, respectively.