Seismic Hazard Epistemic Uncertainty in the San Francisco Bay Area and Its Role in Performance-Based Assessment

Abstract

be approximately estimated as a function of the mean exceedance probability. The distribution of the epistemic uncertainty is found to be dependent on the set of alternative ground motion prediction equations used, but is frequently well approximated by the lognormal distribution. The correlation in the hazard uncertainty is observed to be a function of the separation between the two different intensity levels, and a simple predictive equation is proposed based on the data analysed. Three methods for the propagation of seismic hazard epistemic uncertainty are compared and contrasted using an example of the 30-year collapse probability of a structure. It is observed that, for this example, epistemic uncertainty in the collapse capacity is more influential than that in the seismic hazard.

The seismic demand hazard and importance of the conditioning intensity measure

“…This variation can be considered small in comparison with the magnitude of uncertainties in the estimation of seismic hazard and seismic response itself. For example, Bradley illustrated that epistemic uncertainties in the results of seismic hazard analyses are typically in the range of 0.5–1.5 (lognormal standard deviation in exceedance probability), whereas the uncertainties in seismic response are in the order of 0.4. As discussed in the subsequent section, the additional 5–10% error ratio observed in Figure due to the interpolation of EDP | IM j (i.e.…”

Consideration and Propagation of Ground Motion Selection Epistemic Uncertainties to Seismic Performance Metrics

“…Conducting RHAs requires an appropriate representation of the seismic hazard at the site, which can be achieved by selecting ground motion time series recorded during past earthquakes and/or from an ensemble of simulated ground motions. While various methods have been proposed to select ground motions for seismic response analysis (e.g., Baker 2011, Bommer and Acevedo 2004, Bradley 2012b, Jayaram et al 2011, Kottke and Rathje 2008, McGuire 1995, Shome et al 1998 Postdoctoral Fellow, University of Canterbury, Christchurch, New Zealand; karim.tarbali@canterbury.ac.nz b) Professor, University of Canterbury, Christchurch, New Zealand c) Visiting Professor, Stanford University, Stanford, CA d) Associate Professor, Stanford University, Stanford, CA Wang, 2011) and to address epistemic uncertainty in seismic hazard (e.g., Abrahamson and Bommer 2005, Bommer et al 2010, Bommer and Scherbaum 2008, Bradley 2009, Cotton et al 2006, Douglas et al 2014, Kulkarni et al 1984, McGuire et al 2005, Musson 2005), the only past study concerned with the explicit consideration of seismic hazard epistemic uncertainty in the selection of ground motions is by Lin et al (2013), which focused on epistemic uncertainty in empirical ground motion models (GMMs) and the subsequent computation of conditional pseudo-spectral acceleration (SA) as the target for the ground motion selection process.…”

A ground motion selection procedure for enforcing hazard consistency and estimating seismic demand hazard curves

“…In particular, the relatively wide CIs near collapse in Figure a indicate that the SDHC estimate from a single execution with n = 100 is not very repeatable; that is, another execution with n = 100 will likely produce a different estimate of the SDHC. The repeatability of an SDHC estimate is measured herein by the standard deviation of the logarithm of the collapse rate, denoted by σ C , because exceedance rates may be considered to be approximately lognormally distributed ; the values of σ C for each choice of sample size are displayed in Figure .…”

“…If smaller values of σ C are desired, then n should be increased. To provide some context for such values of σ C , note that the epistemic uncertainty in seismic hazard and in seismic response is on the order of 0.5–1.5 and 0.4, respectively . The recommended range of is tantamount to performing 25–50 RHAs at 10 intensity levels in a PSDA, except that a nonparametric approach is employed in the proposed procedure (Equation ), whereas a parametric approach is typically employed in PSDA.…”