Understanding the seismic risk to infrastructure and society is critical for building resilient communities. Recent developments in seismic risk assessment methodologies have equipped engineers with more powerful toolsets for quantifying risk and explicitly linking risk to design and policy decisions. One such development is the FEMA P-58 (P-58) methodology, which can be used to assess risk in terms of dollars, deaths and downtime for individual buildings (FEMA 2012). P-58 has seen increased use in recent years by the engineering profession for both new building design and the assessment of existing structures (Haselton 2018). However, as the adoption of P-58 grows, the question remains; can we trust P-58 results? In particular, how well do the numbers from a P-58 analysis match what we have observed from previous earthquakes and more mature seismic loss methodologies, especially Hazus (FEMA 2003)?
To evaluate the quality of results obtained through a P-58 assessment, this paper compares the repair costs estimated using the P-58 methodology, with repair costs predicted by Hazus for over 50,000 representative building models that vary based on structural systems, configuration, age, and location. Hazus is selected for comparison because it is based on observations from several major U.S. earthquakes and has been relied upon by the engineering and risk assessment community for over 20 years. This study finds that P-58 repair costs compare well with Hazus predictions for building types, configurations, locations, and ages for which HAZUS predictions are based on earthquake observations. Deviations in comparisons occur where Hazus is essentially extrapolated from available earthquake data and based solely on engineering judgement. The study also illustrates the greater resolution of the P-58 framework to capture variations in building characteristics beyond those captured in Hazus.
FEMA . Seismic Performance Assessment of Buildings. FEMA P-58, Prepared by ATC.
FEMA . HAZUS-MH Technical Manual. FEMA, Washington D.C.
Haselton and Hamburger . Resilient Design and Risk Assessment using FEMA P-58 Analysis, Structures Magazine, March 2018.