Decision analysis for seismic retrofit of structures

This paper presents a methodology that can be used to make informed decisions on whether or not to retrofit structures for seismic events based on the expected economic benefit due to retrofitting. The seismic fragility of a given structure as well as the seismic hazard at a specific building location is incorporated into the decision-making process. The prescribed methodology is used to study two identical reinforced concrete buildings, one located in Memphis, Tennessee and one in San Francisco, California. The probabilities of failure and generalized reliability indices are calculated for the identical structures in both locations. A parametric analysis is performed to determine the effects that achievable loss reduction, investment return period, and retrofit cost have on the economic feasibility of seismic retrofitting in Memphis and San Francisco. A case study is conducted to find the impact of a modest retrofit strategy applied to the identical buildings in Memphis and San Francisco. The probabilities of failure and generalized reliability indices are calculated for the retrofitted building in both locations and compared to the corresponding values for the original buildings. The results of the parametric analysis and case study are used to determine the effects of building location on retrofit feasibility.