Browsing by Author "Crempien, J. G. F."

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A computational workflow for rupture‐to‐structural‐response simulation and its application to Istanbul
(Wiley, 2020-10) Zhang, W. Y.; Restrepo, D.; Crempien, J. G. F.; Erkmen, Bülent; Taborda, R.; Kurtuluş, Aslı; Taciroglu, E.; Civil Engineering; ERKMEN, Bülent; KURTULUŞ, Asli
Scenario-based earthquake simulations at regional scales hold the promise in advancing the state-of-the-art in seismic risk assessment studies. In this study, a computational workflow is presented that combines (i) a broadband Green's function-based fault-rupture and ground motion simulation-herein carried out using the "UCSB (University of California at Santa Barbara) method", (ii) a three-dimensional physics-based regional-scale wave propagation simulation that is resolved at fmax=11.2 Hz, and (iii) a local soil-foundation-structure finite element analysis model. These models are interfaced with each other using the domain reduction method. The innermost local model-implemented in ABAQUS-is additionally enveloped with perfectly matched layer boundaries that absorb outbound waves scattered by the structures contained within it. The intermediate wave propagation simulation is carried out using Hercules, which is an explicit time-stepping finite element code that is developed and licensed by the CMU-QUAKE group. The devised workflow is applied to a 80x40x40 km3 region on the European side of Istanbul, which was modeled using detailed soil stratigraphy data and realistic fault rupture properties, which are available from prior microzonation surveys and earthquake scenario studies. The innermost local model comprises a chevron-braced steel frame building supported by a shallow foundation slab, which, in turn, rests atop a three-dimensional soil domain. To demonstrate the utility of the workflow, results obtained using various simplified soil-structure interaction analysis techniques are compared with those from the detailed direct model. While the aforementioned demonstration has a limited scope, the devised workflow can be used in a multitude of ways, for example, to examine the effects of shallow-layer soil nonlinearities and surface topography, to devise site- and structure-specific seismic fragilities, and for calibrating regional loss models, to name a few.
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Regional-scale seismic fragility, loss, and resilience assessment using physics-based simulated ground motions: An application to istanbul
(Wiley, 2023-05) Zhang, W.; Chen, P. Y.; Crempien, J. G. F.; Kurtuluş, Aslı; Arduino, P.; Taciroglu, E.; Civil Engineering; KURTULUŞ, Asli
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.
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A suite of broadband physics-based ground motion simulations for the Istanbul region
(Wiley, 2023-04) Zhang, W.; Crempien, J. G. F.; Kurtuluş, Aslı; Chen, P.-Y.; Arduino, P.; Taciroglu, E.; Civil Engineering; KURTULUŞ, Asli
Physics-based earthquake ground motion simulations (GMS) have acquired significant growth over the last two decades, mainly due to the explosive developments of high-performance computing techniques and resources. These techniques benefit high/medium seismicity regions such as the city of Istanbul, which presents insufficient historical ground motion data to properly estimate seismic hazard and risk. We circumvent this reality with the aid of the Texas Advanced Computing Center (TACC) facilities to perform a suite of 57 high-fidelity broadband (8–12 Hz) large-scale physics-based GMS for a region in Istanbul, Turkey. This paper focuses on the details of simulated GMS: (i) validation of the GMS approach against recorded ground motions produced by the 2019 (Formula presented.) Silivri earthquake; (ii) characteristics of 57 different source models, which aim to consider the uncertainties of many fault rupture features, including the length and width, dip, strike, and rake angles of considered fault planes, as well as hypocenter locations and earthquake magnitudes ranging between (Formula presented.) 6.5 and 7.2; (iii) high-resolution topography and bathymetry and seismic data that are incorporated into all GMS; (iv) simulation results, such as PGAs and PGVs versus (Formula presented.) and distances to fault ruptures ((Formula presented.)), of 2912 surface stations for all 57 GMS. More importantly, this research provides a massive database of displacement, velocity and acceleration time histories in all three directions over more than 20,000 stations at both surface and bedrock levels. Such site-specific high-density and -frequency simulated ground motions can notably contribute to the seismic risk assessment of this region and many other applications.