Browsing by Author "Poulos, A."

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    Construction and risk evaluation of a water distribution network under seismic hazard in central Chile
    (2021) Llera Martin, Juan Carlos de la; Castro, S.; Arróspide, F.; Poulos, A.; Alberto, Yolanda
    Water distribution is of critical importance under regular conditions, and more so in times of an emergency induced by a large natural event, which also stresses the performance of other lifelines and critical infrastructure. Being able to compare the network operation in normal conditions with, that during an extreme event, is useful for decision makers in defining investment priorities for mitigation plans. This work aims to perform risk analysis under seismic hazard on the water network of a large conurbation in central Chile formed by the cities of Valparaíso and Viña del Mar. A hydraulic network model of the water network was developed first considering the physical properties of network elements and their estimated head losses. Herein, the methodology for the network construction is described, which combines datasets available in official repositories. As a first attempt, damage scenarios are generated using peak ground acceleration maps constructed using a ground motion prediction model. Pipeline failure is evaluated using fragility functions available in the literature; hydraulic analyses are then carried out on the damaged network. The performance of the network is measured in terms of connectivity (loss) and percentage of unsupplied demand. Finally, a seismic risk analysis on these two indices is presented to enable identification of the relevant characteristics of the constructed network.
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    Impact of earthquake magnitude on the estimation of tsunami evacuation casualties
    (2018) Castro, S.; Poulos, A.; Urrutia, A.; Herrera, J. C.; Cienfuegos, R.; Llera Martin, Juan Carlos de la
    The importance of evacuation plans has been widely proven in recent tsunami events. Several evacuation models have been proposed to develop these plans and estimate city evacuation times. Typically, single extreme earthquake scenarios are used in these estimations; however, the impact of earthquake damage on the evacuation routes is usually neglected in these models. This article deals with the evaluation of the effect of three different earthquake magnitudes and the following tsunamis. Several spectral accelerations were sampled for each magnitude to estimate city damage, and from there the reduced capacity of evacuation routes due to earthquake debris. An agent-based evacuation model was used to assess the evacuation times for the city of Iquique, located in north Chile. Results show significant variability for different magnitude scenarios, thus leading to an observed increment on evacuation times up to 40% and an increase in the number of casualties due to the evacuation delay caused by earthquake debris spread on the evacuation routes
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    Predictive capacity of topological measures in evaluating seismic risk and resilience of electric power networks
    (ELSEVIER SCI LTD, 2022) Ferrario, Elisa; Poulos, A.; Castro, S.; Llera Martin, Juan Carlos de la; Lorca Gálvez, Álvaro Hugo
    Electric Power Networks (EPNs) play a fundamental role in the wellbeing of modern societies and recovery of societal functions after an earthquake. Risk and resilience analyses may identify useful network characteristics to improve EPN response and recovery during and after a severe seismic event. This work computes different functional measures in order to: (i) estimate the actual risk and resilience of EPNs; and (ii) evaluate the predictive capacity of different topological measures (TMs) relative to the EPN earthquake risk performance. The analysis is carried out on the Chilean EPN at the national, regional and substation level, by using a detailed model of the network. EPN operation was modeled using the DC optimal power flow model from the time of earthquake occurrence until full system recovery using the Seismic Probabilistic Risk Assessment framework. Seismic risk and resilience estimations of Energy Not Supplied (ENS) and number of hours with ENS have been correlated with six network TMs. Linear correlation results show that TMs provide, in general, limited insight into the criticality of the Chilean EPN. In spite of that, the strongest correlation was observed for the degree TM. Moreover, the Damage Consequence Index confirmed the rather uniformly distributed seismic risk along the country.
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    Scenario-based seismic performance assessment of a Chilean hospital
    (2015) Poulos, A.; Favier, P.; Vásquez, J.A.; Llera Martin, Juan Carlos de la
    Hospitals are critical facilities that are essential for providing first-aid response to communities in the aftermath of disasters such as earthquakes. The seismic performance of these facilities is highly dependent on the structural behaviour and the vulnerability of non-structural contents to damage. However, earthquake-induced structural damage has not yet been considered directly when assessing hospital loss of functionality. Our approach uses inelastic structural analysis to compute the earthquake response, fragility functions to assess non-structural and component damage, and a discrete event model to simulate the response of the emergency room of the hospital. Further, the seismic performance of the hospital is characterized by the increase of patient waiting times after the earthquake. The model is then tested with the 2014 Mw 8.2 Pisagua earthquake, which struck off the coast of northern Chile. Analyses show that hospital performance is mainly affected by two factors: the arrival rate of patients and healthcare unit downtime. The proposed model is applicable to a wide range of seismic scenarios, which is key in estimating risk for the loss of performance of hospitals during an earthquake