Earthquake Loss Estimates and Policy Implications for Nonductile Concrete Buildings in Los Angeles

The collapse potential of nonductile concrete buildings represents a substantial life safety hazard globally that can be mitigated through carefully crafted policy. Mitigation policy should be approached incrementally by (1) understanding problem scale, (2) screening for low- and high-risk buildings, (3) performing engineering analysis for potentially vulnerable buildings, and (4) retrofit or replacement of high-risk structures. This research addresses initial stages of this sequence for Los Angeles, California. The intent was to investigate approaches for informing mitigation priorities by: characterizing the inventory of approximately 1,500 pre-1976 concrete buildings; estimating risk, including identification of building types that contribute most substantially to the risk; and investigating the impact of retrofit policy alternatives. Loss estimates for scenario events are based on the HAZUS™ Advanced Engineering Building Module. Depending on model assumptions, losses range from $1.8 to $28.5 billion and <50 to 8,300 fatalities. We investigate proposals targeting vulnerable buildings for retrofit as compared to retrofitting all buildings in the inventory. Awareness raised by this research contributed to the formation of the Los Angeles Mayoral Seismic Safety Task Force, which developed policy proposals.