Preliminary Results of a Cost-Benefit Assessment of Replacing Seismically Vulnerable Non-Ductile Reinforced Concrete Frame Structures

摘要

This study uses cost-benefit assessment to evaluate the cost-effectiveness of replacing existing seismically deficient reinforced concrete frames to improve their seismic safety. This assessment is based on a set of typical older California reinforced concrete frame structures, whose seismic performance, measured in terms of the risk of earthquake-induced collapse, fatalities and repair costs have been evaluated in previous studies (Liel et al. 2009, Liel and Deierlein 2008). The cost-benefit assessment accounts for the costs of replacement and the benefits of these actions, including improved seismic safety and reduced earthquake damage and repairs. While the assessments show that replacing these vulnerable structures can significantly reduce the life safety and repair cost risks, the cost-benefit rates (assuming a value of life saved of $2 million) are generally greater than one, suggesting that the costs outweigh the benefits. The breakeven point in the cost-benefit analyses (for building replacement) occurs at a cost per life saved of approximately $5 million. Alternatively, if building retrofit could achieve comparable life safety to a new building, it would be cost effective (assuming a value per life saved of $2 million) for retrofit costs less than $98 per square foot of building (on average).