Regional‐scale seismic fragility, loss, and resilience assessment using physics‐based simulated ground motions: An application to Istanbul

Abstract

Using results from 57 large‐scale physics‐based fault‐rupture and wave propagation simulations, this research aims to evaluate the seismic risk, loss, and resilience of more than 16,000 reinforced concrete buildings in the Zeytinburnu district of Istanbul, Turkey. For each building and under each earthquake scenario, the spatially varying site‐specific simulated ground motions were used for performing three‐dimensional nonlinear time‐history analyses. The resulting structural responses—such as peak story drift ratios (PSDR) and peak floor accelerations (PFAs)—were utilized to conduct three region‐scale tasks: (i) building‐ and site‐specific seismic fragility analysis for both structural and nonstructural components of each building; (ii) intensity‐based seismic loss assessment using the FEMA P58 methodology and Monte Carlo simulations; and (iii) resilience evaluation based on the expected time of recovery predicted through FEMA P58. Moreover, both inertial and kinematic soil–structure interaction (SSI) effects were considered using a substructuring method for all three tasks. Site‐specific soil properties were utilized to compute the coefficients of soil springs and dashpots, as well as the foundation input motions. The SSI effects were investigated by comparing the fragility, loss, and resilience indices obtained with and without considering SSI.

Engineering validation of BB-SPEEDset, a data set of near-source physics-based simulated accelerograms

“…near-source regions and very soft basin sites), without making use of either linear scaling or of spectral matching, which may alter significantly the physical nature of the input motions and, consequently, the meaningfulness of results; Provide ensembles of input motions for NLTHA of critical structures (e.g. Nuclear Power Plants, see Abell et al, 2018;Castro-Cruz et al, 2021;Smerzini et al, 2023), containing those source-, region-, and site-specific features that may not be included in suite of motions extracted from global ground motion data sets; Better constrain the input definition particularly for: (1) the calibration of both empirical and analytical fragility curves (Rosti et al, 2023;Zhang et al, 2023); (2) spatially variable multi-support excitations for the seismic analysis of infrastructure systems (Smerzini, 2018;Taslimi and Petrone, 2023); (3) specific near-field studies requiring sets of pulse-like ground motion series; (4) region-specific ground motions in large urban areas, including their spatial correlation (e.g. Chen and Baker, 2019;Infantino et al, 2021b;Schiappapietra and Smerzini, 2021).…”

“…Better constrain the input definition particularly for: (1) the calibration of both empirical and analytical fragility curves (Rosti et al, 2023; Zhang et al, 2023); (2) spatially variable multi-support excitations for the seismic analysis of infrastructure systems (Smerzini, 2018; Taslimi and Petrone, 2023); (3) specific near-field studies requiring sets of pulse-like ground motion series; (4) region-specific ground motions in large urban areas, including their spatial correlation (e.g. Chen and Baker, 2019; Infantino et al, 2021b; Schiappapietra and Smerzini, 2021).…”

A suite of broadband physics‐based ground motion simulations for the Istanbul region

“…Three intertwined factors that highly affect the accuracy and usability of physics‐based GMS are: (1) maximum frequency, $$f_{\text{max}}$$; (2) minimum shear wave velocity, $$V_{s\nobreakspace \text{min}}$$; and (3) number of simulations. $$f_{\text{max}}$$ not only determines the maximum discernible frequency in the time‐series of ground motions, which significantly controls some important ground motion IMs that only exist in the high‐frequency range, for example, PGA, 28 but also influences its applicability for nonlinear time‐history analysis of structures, particularly, with short periods. However, higher simulation frequencies require finer meshes and a cubically growing number of FEs, which demands more computational power.…”

Framework for a City’s Performance Assessment in the Case of an Earthquake

“…Moreover, the project aimed to create a Fragility Function Manager tool for large-scale vulnerability assessment including the fragility curve library [30]. However, it is worth mentioning that due to all the various factors influencing the seismic response of structures in relation to both structural and foundation components (e.g., steel and confinement ratios, shear walls, softstories, irregularities, foundation dimensions, and types), the accuracy of fragility curves may differ considerably [31]. To address the issue of inaccuracy, recent studies have tried to move beyond the rough building classification by suggesting various supplementations and additional criteria for a more precise vulnerability evaluation [25,32,33].…”