Browsing by Author "Poulos, Alan"
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- ItemEarthquake response sensitivity of complex infrastructure networks(2020) Llera Martin, Juan Carlos de la; Monsalve, Mauricio; Ferrario, Elisa; Allen, E.; Chamorro, A.; Castro, S.; Alberto, Yolanda; Arróspide, Felipe; Poulos, Alan; Candia, G.; Aguirre, P.Resilience of complex infrastructure networks is critical in achieving earthquake resilience in urban environments. Perhaps due to their modeling complexity, very few research studies have addressed sensitivity of the network response to a severe earthquake hazard field. This research aims to characterize earthquake response sensitivity as a function of different topological parameters of 5 critical complex networks in central Chile, covering the electric, transportation, and drinking water networks. Central Chile was selected because it amounts for almost 50% of the country’s population. What is also particular about this setting, is that the seismic characteristics of the region lead to extended (essentially) N-S strike fault ruptures, which run along the subduction margin defined by the E-W convergence between the South American and Pacific Ocean plates at an unusual rate of about 68 mm/year, thus involving in the strong-motion hazard field geographic scales in the hundreds of kilometers. It is concluded that node and link topological structures differ considerably between these complex systems, which are characterized by several different well-known centrality parameters and other interesting indices and network-class discriminators. Secondly, a component criticality analysis under an earthquake hazard field is also presented just in terms of connectivity/service loss, which enables, at least, a rough identification of the robustness of each network as nodes and links are removed. Results from these topological analyses are useful to identify which components are essential in generating larger earthquake resilience. This is the first time such results are obtained for central Chile using very detailed models of these complex networks
- ItemEstimating the impact of earthquake-induced power outages on different economic sectors in Chile(2020) Llera Martin, Juan Carlos de la; Ferrario, Elisa; Monsalve M., Mauricio; Poulos, Alan; Sansavini, GiovanniThe damage induced by strong earthquakes on the components of Electric Power Networks (EPNs) can seriously compromise the ability of these systems to generate and distribute electric power to final users and to interconnected utilities and industries. This results in large-scale impacts across infrastructure systems and economic sectors that rely upon EPNs. The objective of this work is to estimate the economic losses due to the reduction of the Chilean EPN functionality after the occurrence of disruptive seismic events. Economic losses have been estimated, at country and regional level, by applying the following main steps: (1) estimation of ground motion intensity measures for three earthquakes at the location of the EPN system components; (2) evaluation of the physical damage on the EPN system components; (3) evaluation of the EPN system functional consequence; and (4) estimation of the economic impacts on the electricity sectors and on the interconnected economic activities at regional and national level. Results of this analysis allow identifying the most impacted regions on the basis of the most impacted economic activities and can support decision-making for future investments to reduce the economic impacts produced by disruptive seismic events on EPNs and their interdependent industries.
- ItemEvaluating network reduction strategies for consistent risk assessment of critical infrastructures(2020) Llera Martin, Juan Carlos de la; Monsalve M., Mauricio; Ferrario, Elisa; Alberto, Yolanda; Arróspide, Felipe; Castro, Sebastián; Poulos, AlanCritical infrastructure networks are continuously growing, gaining complexity with each urban sprawl, conurbation, technological change, and regulatory update. Consequently, their detailed risk analysis demands large amounts of data, computational resources (required by simulations, optimization, flow equilibria, etc.), and dealing with complex interpretations of the results. This comes with several drawbacks: scarcity of adequately curated data, which instead are usually incomplete and sometimes even incorrect, algorithmic runtime that impairs the full use of Monte Carlo simulations, errors that may propagate extensively, and results that cannot be generalized and extended to other cases. Therefore, researchers have also resorted to analyzing simplified versions of these infrastructure systems. This work evaluates three algorithms for reducing the complexity of infrastructure networks while keeping reasonable accuracy for statistical interpretation. These algorithms transform a detailed graph into a more compact representation, where risk assessments can be performed more easily. The strategies used herein are based on the detection of important edges (backbone detection) and the merging or lumping similar or proximate elements (clustering, contractions). The different complexity reduction algorithms are evaluated on three infrastructure networks, namely: the electric transmission network of Chile, the electric distribution network of the Greater Valparaíso and the drinking water distribution network of the Greater Valparaíso. The experiments show that two of the three graph reduction criteria proposed in this work yield good approximations of the connectivity of the original graphs, when these are reduced to 25% of their size.
- ItemSensitivity analysis and uncertainty quantification of a seismic risk model for road networks(WILEY, 2021) Allen, Eduardo; Chamorro Giné, Marcela Alondra; Poulos, Alan; Castro, Sebastian; Llera Martin, Juan Carlos de la; Echaveguren, TomasNatural hazards may cause significant disruptions to road infrastructure, subsequently affecting road agencies, users, and productive activities. Despite the existence of infrastructure fragilities to seismic hazard and some operational consequences on network mobility, previous research has not modeled risk in terms of traffic disruptions and consequent travel time delays in subduction environments, analyzing the sensitivity to model parameters and quantified model uncertainty. This study proposes a risk framework to evaluate operational consequences in interurban road networks exposed to seismic hazard using travel time delays and propagate uncertainty in the model. Risk values are evaluated using Monte Carlo simulations, and uncertainty is propagated using a polynomial chaos expansion meta-model. The framework was applied to a very critical interurban network in central Chile. Results demonstrate that the parameters that most significantly influence risk are fragility, loss of road capacity, and traffic volume.