Estimating Downtime from Data on Residential Buildings after the Northridge and Loma Prieta Earthquakes

Abstract

The performance-based earthquake engineering (PBEE) methodology developed by the Pacific Earthquake Engineering Research (PEER) center uses data from recent earthquakes to calibrate its loss models. This paper describes a detailed review of building department permit data from the 1989 Loma Prieta earthquake and the 1994 Northridge earthquake. Although the data is limited to wood-framed residential structures, it provides some insight into the length of time between an event and re-occupancy. Based on a review of approximately 4,900 records, the typical repair of damaged multifamily residential buildings required two years and building replacement required almost four years. When this data is supplemented with additional case studies from other events, the capacity to better calibrate downtime models will improve, particularly if construction-repair times are separated from estimates of the time gap between closure and start-of-repair.