Site dependence and record selection schemes for building fragility and regional loss assessment

Abstract

Summary When performing loss assessment of a geographically dispersed building portfolio, the response or loss (fragility or vulnerability) function of any given archetype building is typically considered to be a consistent property of the building itself. On the other hand, recent advances in record selection have shown that the seismic response of a structure is, in general, dependent on the nature of the hazard at the site of interest. This apparent contradiction begs the question: Are building fragility and vulnerability functions independent of site, and if not, what can be done to avoid having to reassess them for each site of interest? In the following, we show that there is a non‐negligible influence of the site, the degree of which depends on the intensity measure adopted for assessment. Employing a single‐period (e.g., first‐mode), spectral acceleration would require careful record selection at each site and result to significant site‐to‐site variability of the fragility or vulnerability function. On the other hand, an intensity measure comprising the geometric mean of multiple spectral accelerations considerably reduces such variability. In tandem with a conditional spectrum record selection that accounts for multiple sites, it can offer a viable approach for incorporating the effect of site dependence into fragility and vulnerability estimates. Copyright © 2017 John Wiley & Sons, Ltd.

Quantification of modelling uncertainty in existing Italian RC frames

“…Future research could investigate different IMs that are more efficient by reducing the associated dispersion in the resulting demand parameters. Some potential candidates would be those that are not linked solely to the T 1 of the building, such as those recently proposed that define the IM as a function of the spectral demands in range of periods above and below the T 1 .…”

Seismic intensity measures for above‐ground liquid storage tanks

“…It should be noted that behind the choice of such high period, upper bounds for the AvgS a lie in the nonlinear‐elastic nature of the joystick model, which forces the system to remain on the low‐stiffness hardening branch during loading/unloading and reloading, in contrast to the elastic segments of unloading/reloading of an elastic‐hardening system. In general, the concept of combined S a values may also be deemed a strong candidate IM for the seismic risk evaluation of a group of tanks with varying geometry (and thus T i and T c ) . This is an interesting problem that requires thorough investigation and is expected to be covered in a future direction of our research.…”

“…Studies by many researchers have shown that a wide variety of IM s defined according to the general frame of Equation can offer substantial efficiency and sufficiency for building structures …”

“…In general, the concept of combined S a values may also be deemed a strong candidate IM for the seismic risk evaluation of a group of tanks with varying geometry (and thus T i and T c ). 22,28,29 This is an interesting problem that requires thorough investigation and is expected to be covered in a future direction of our research. Finally, the vectors of {PGA, S a (T c )} and {S a (T i ), S a (T c )} are considered as a potentially more accurate way of incorporating the effect of T c without compromising that of T i as done in a scalar combination.…”

Q-Factor Verification of a 6-Storey Concentrically Braced Frame via the Innoseis Risk-Based Approach

“…If considerable difference exists among the different first mode periods, one should consider using two different definitions of AvgSa, one for low/mid-rise structures (shorter periods) and another for high-rise ones (longer periods), for better fidelity. In any case, ground motion records need to be selected for each definition of AvgSa at a given set of sites [12,13], while mean hazard curves are required for each definition of AvgSa and at each separate site.…”