Browsing by Author "Zhang, W."

Now showing 1 - 8 of 8

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A cost-benefit analysis of sensor quality and spatial density for rapid regional post-event seismic damage assessment: Application to Istanbul
(Elsevier, 2022-12) Cheng, Q.; Liao, W.; Fei, Y.; Tian, Y.; Lu, X.; Zhang, W.; Ghahari, F.; Kurtuluş, Aslı; Taciroglu, E.; Civil Engineering; KURTULUŞ, Asli
A quantitative evaluation of the influence of sensor quality and spatial density on the results of rapid regional seismic damage evaluations of buildings can provide an important reference for the deployment of a strong-motion network. However, the influence of sensor quality and spatial density on seismic damage assessment is still unclear. Therefore, a cost-benefit analysis framework of sensor quality and spatial density for rapid regional post-event seismic damage assessment is proposed. In this framework, a simulation method for sensor-recorded ground motions and an interpolation-based ground motion field refinement method are used to consider the influence of the quality and density of the sensor network. The accuracies of seismic damage assessments with different sensor layout schemes were compared using the time-history analysis-based regional seismic damage assessment method, through which the influence of sensor quality and spatial density on the seismic damage assessment can be quantitatively evaluated. Finally, the Zeytinburnu district of Istanbul was selected as an example for illustrating the proposed framework. The main conclusions are as follows: (1) the spatial density of the sensors used is more significant for improving the accuracy of a seismic damage assessment than the quality of the sensors used; (2) the influence of population density can be considered using the proposed framework; and (3) the proposed framework can quantitatively consider the influence of sensor quality and spatial density on the rapid regional seismic damage assessment of buildings, which provides an important reference for the deployment of a strong-motion network for a given budget.
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Coverage properties of clustered wireless sensor networks
(ACM, 2010-08) Machado, R.; Zhang, W.; Wang, G.; Tekinay, Şirin; Electrical & Electronics Engineering; TEKİNAY, Şirin
This article studies clustered wireless sensor networks (WSNs), a realistic topology resulting from common deploymentmethods.We study coverage in naturally clustered networks of wireless sensor nodes, as opposed to WSNs where clustering is facilitated by selection. We show that along with increasing the vacancy in random placement of nodes in a WSN, it also alters the connectivity properties in the network.We analyze varying levels of redundancy to determine the probability of coverage in the network. The phenomenon of clustering in networks of wireless sensor nodes raises interesting questions for future research and development. The article provides a foundation for the design to optimize network performance with the constraint of sensing coverage.
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Diffusion-based approach to deploying wireless sensor networks
(Inderscience, 2010) Machado, R.; Tekinay, Şirin; Zhang, W.; Wang, G.; Electrical & Electronics Engineering; TEKİNAY, Şirin
An important objective of Wireless Sensor Networks (WSNs) is to reliably sense data about the environment in which they are deployed. Reliability in WSNs has been widely studied in terms of providing reliable routing protocols for message dissemination and reliability of communication from sink to sensors. In this work, we define a reliability metric by the amount of data sensed by the network. In order to satisfy this reliability constraint, we propose a diffusion-based approach for a deployment pattern for the sensor nodes. We show that this deployment pattern achieves sufficient coverage and connectivity and requires lesser number of sensors than popular regular deployment patterns. We further obtain the bounds on establishing connectivity between nodes in the WSN and extend this analysis for heterogeneous WSNs.
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Influence of accelerometer type on uncertainties in recorded ground motions and seismic damage assessment
(Springer, 2022-07) Liao, W.; Fei, Y.; Ghahari, F.; Zhang, W.; Chen, P. Y.; Kurtuluş, Aslı; Yen, C. H.; Cheng, Q.; Lu, X.; Taciroglu, E.; Civil Engineering; KURTULUŞ, Asli
Strong motion data recorded by strong-motion networks are essential for preventing and mitigating earthquake disasters, such as earthquake early warning and earthquake emergency responses, and the type of accelerometer can significantly influence the quality of recorded ground motions (GMs) and the subsequent usage. Different types of accelerometers vary significantly in both the price and the quality of collected data, because cheap accelerometers generate non-negligible self-noise and reduce the quality of the collected GMs. However, the effects of the accelerometer type and spatial density on the accuracy of GM-based seismic damage assessment are still unknown. The present study attempts to quantify these effects comprehensively at a regional scale. First, a method to simulate recorded data from different quality sensors is devised, using characteristics of existing low-, medium-, and high-quality accelerometers. These simulations use input data from either the Pacific Earthquake Engineering GM database or from a high-fidelity fault rupture and regional wave propagation simulation. Subsequently, the simulated sensor data are used to assess the seismic damage to typical buildings at a city scale. The results indicate that low-quality sensors found in most smartphones are currently insufficient for assessing seismic damage. Medium-quality accelerometers (MEMS-based instruments), on the other hand, can provide feasible solutions for cost-effective city-scale deployment and may offer deployment options that are superior to sensor networks with high-quality accelerometers.
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Influence of sensor density on seismic damage assessment: A case study for istanbul
(Seismological Society of America, 2022-08) Cheng, Q.; Fei, Y.; Lu, X.; Liao, W.; Zhang, W.; Chen, P. Y.; Kurtuluş, Aslı; Ghahari, F.; Vela, V.; Taciroglu, E.; Civil Engineering; KURTULUŞ, Asli
The strong ground motions (GMs) recorded by strong motion networks are significant to increase the accuracy of seismic damage assessment. However, the influence of sensor density on seismic damage assessment remains unclarified. Therefore, a workflow is proposed in this study to quantitatively analyze the influence of sensor density on seismic damage assessment. The scenario-based earthquake simulation method is first used to provide the time history of GM at each location as the ground truth of the analysis. Subsequently, a GM prediction method, namely the interpolation method, is adopted to predict GMs at locations without sensors using measuring data from the limited sensors. Finally, the building scale and region scale seismic damage under different sensor densities are compared to quantitatively analyze the influence of sensor density on seismic damage assessment. A detailed case study for Zeytinburnu District, Istanbul, Turkey, is performed to demonstrate the proposed methods. The findings of this study can provide an important reference for seismic damage assessment and the deployment of strong motion networks.
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An investigation of the effects of surface topography on the seismic structural demands for a region of istanbul
(CRC Press, 2019) Zhang, W.; Taciroglu, E.; Restrepo, D.; Taborda, R.; Kurtuluş, Aslı; Ansal, Mustafa Atilla; Civil Engineering; Silvestri, F.; Moraci, N.; KURTULUŞ, Asli; ANSAL, Mustafa Atilla
In this study, we provide preliminary results from an ongoing study—funded by The Scientific and Technological Research Council of Turkey, TUBITAK—investigating the effects of site-specific surface topography and soil stratigraphy on dynamic soil-structure interaction (SSI) behavior of structures located within a region of Istanbul. To achieve this, nonlinear time-domain responses of various soil-foundation-structure systems subjected to strong remote earthquake excitations for various site conditions will be investigated. The goal is to transform SSI analyses to consider realistic site conditions. An important part of this effort involves the creation of a map of topography-induced SSI response amplification factors for the south European side of Istanbul by performing 3D simulations using real site topography and soil stratigraphy data, and realistic bedrock ground motions, which are available from previously completed earthquake scenario and seismic microzonation studies. This paper presents preliminary results of large-scale 3D simulations performed for the south European side of Istanbul.
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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.