Risk-benefit-based design decisions for low-probability/high consequence earthquake events in Mid-America

Decision-making under uncertainty is a difficult task when the information available is scarce and consequences are large. Such is the case in assessing vulnerabilities of buildings and transportation facilities to earthquakes in Mid-America where large events have occurred in the past and yet very few events have been recorded at intensity levels of interest to engineers. A rational approach to this problem requires careful consideration of both aleatory and epistemic uncertainties in the demand and capacity of the systems under consideration, the performance of those systems, the consequences of unsatisfactory performance in terms of direct damages and costs incurred over time, and costs required for retrofitting existing systems or building new systems. A balance must be achieved between risk and benefit for an optimal design decision. Some recent developments in this approach as it applies to design and retrofit for earthquake effects are briefly reviewed. A risk-benefit-based procedure is proposed and illustrated for buildings that must withstand earthquake effects in Mid-America.