Risk-Based Prioritization of a Building Portfolio for Retrofit

This paper puts forward a risk-based approach to prioritize a portfolio of buildings for retrofit. A new set of local sensitivity measures is proposed to rank the buildings based on the optimal mitigation of risk to the entire portfolio. The proposed measures employ the derivative of various risk measures with respect to the cost of retrofit for each building. These risk measures are the mean and higher moments of the total portfolio cost probability distribution. The total portfolio cost comprises the construction cost due to retrofit and the repair cost due to damage. The proposed sensitivity measures quantify the reduction of risk to the entire portfolio per dollar spent on retrofitting each building. They provide the flexibility to prioritize under risk-neutrality and risk-aversion. To quantify the risk, reliability methods were employed in which many interacting probabilistic models evaluate the costs. The proposed methodology was applied to prioritizing 114 masonry school buildings in Iran for seismic retrofit. To this end, models were developed to predict the repair and the retrofit cost of masonry structures.