Framework for Lifecycle Cost Assessment of Steel Buildings under Seismic and Wind Hazards

Despite the importance of considering multiple extreme events when designing structures, the current treatment of multiple hazard design in code provisions and assessment guidelines is rather vague. This is primarily because design and assessment of structures have traditionally been geared toward meeting the demand of a single hazard. In recent years, there has been a spike in interest by researchers and engineers in evaluating and designing structures for different hazard combinations. In this paper, a probabilistic framework is provided for assessing design alternatives based on estimating the lifecycle cost for two steel buildings with different heights subjected to different seismic and wind intensities. The intensities are specified based on probability of exceedance as per code standards. The total lifecycle cost is estimated using the initial cost and failure cost where the failure cost is a function of the probability of failure, which is calculated based on specified performance objectives that are evaluated using nonlinear time-history analyses in combination with the first-order reliability method. The analysis results clearly show that obtaining a minimum lifecycle cost depends on the probability of exceedance being combined for every hazard and the natural frequency of the structure considered. The results highlight the importance of considering lifecycle cost as an essential component of performance-based engineering for the design of new structural systems to meet the demand of multiple hazards. (C) 2016 American Society of Civil Engineers.