This paper examines the question of which sources of uncertainty most strongly affect the repair cost of a building in a future earthquake. Uncertainties examined here include spectral acceleration, ground-motion details, mass, damping, structural force-deformation behavior, building-component fragility, contractor costs, and the contractor's overhead and profit. We measure the variation (or swing) of the repair cost when each basic input variable except one is taken at its median value, and the remaining variable is taken at its 10 th and at its 90 th percentile. We perform this study using a 1960s highrise nonductile reinforced-concrete moment-frame building. Repair costs are estimated using the assembly-based vulnerability (ABV) method. We find that the top three contributors to uncertainty are assembly capacity (the structural response at which a component exceeds some damage state), shaking intensity (measured here in terms of damped elastic spectral acceleration, S a ), and details of the ground motion with a given S a .

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A seismic risk assessment is often performed on behalf of a buyer of commercial buildings in seismically active regions. One outcome of the assessment is that a probable maximum loss (PML) is computed. PML is of limited use to real-estate investors as it has no place in a standard financial analysis and reflects too long a planning period. We introduce an alternative to PML called probable frequent loss (PFL), defined as the mean loss resulting from shaking with 10% exceedance probability in 5 years. PFL is approximately related to expected annualized loss (EAL) through a site economic hazard coefficient (H) introduced here. PFL and EAL offer three advantages over PML: (1) meaningful planning period; (2) applicability in financial analysis (making seismic risk a potential market force); and (3) can be estimated using a single linear structural analysis, via a simplified method called linear assembly-based vulnerability (LABV) that is presented in this work. We also present a simple decision-analysis framework for real-estate investments in seismic regions, accounting for risk aversion. We show that market risk overwhelms uncertainty in seismic risk, allowing one to consider only expected consequences in seismic risk. We illustrate using 15 buildings, including a 7-story nonductile reinforced-concrete moment-frame building in Van Nuys, California, and 14 buildings from the CUREE-Caltech Woodframe Project.

We examine seismic risk from the commercial real estate investor's viewpoint. We present a methodology to estimate the uncertain net asset value (NAV) of an investment opportunity considering market risk and seismic risk. For seismic risk, we employ a performance-based earthquake engineering methodology called assembly-based vulnerability (ABV). For market risk, we use evidence of volatility of return on investment in the United States. We find that uncertainty in NAV can be significant compared with investors' risk tolerance, making it appropriate to adopt a decision-analysis approach to the investment decision, in which one optimizes certainty equivalent, CE, as opposed to NAV. Uncertainty in market value appears greatly to exceed uncertainty in earthquake repair costs. Consequently, CE is sensitive to the mean value of earthquake repair costs but not to its variance. Thus, to a real estate investor, seismic risk matters only in the mean, at least for the demonstration buildings examined here.

Most seismic risk assessments for economic decision-making of commercial buildings are based on a risk metric called probable maximum loss (PML) that is associated with losses from an earthquake shaking severity with a 500-year return period. For various reasons, PML is a poor metric for economic performance assessment. This paper introduces an analogous measure, the probable frequent loss (PFL), defined as the mean loss resulting from shaking with 10% exceedance probability in 5 years (an approximately 50-year event). It overcomes many of the problems of PML, and offers the advantage that expected seismic lifecycle costs and expected annualized loss are approximately proportional to PFL through a seismic hazard coefficient that depends on site characteristics, fundamental period, and damage shaking threshold, and can be tabulated for ready use. A brief review is given of a building-specific seismic vulnerability method that may be used to calculate PFL.