Browsing by Author "Candia, Gabriel"

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    A Consistently Processed Strong-Motion Database for Chilean Earthquakes
    (Seismological Society of America, 2022) Castro, Sebastián; Benavente, Roberto; Crempien de la Carrera, Jorge; Candia, Gabriel; Llera Martin, Juan Carlos de la
    © Seismological Society of America.Since the 1985 M 8.0 central Chile earthquake, national strong-motion seismic networks have recorded ten megathrust earthquakes with magnitudes greater than M 7.5 at the convergent margin, defined by the contact between the Nazca and South American plates. The analysis of these earthquake records have led to improved hazard analyses and design codes for conventional and seismically protected structures. Although strong-motion baseline correction is required for a meaningful interpretation of these records, correction methods have not been applied consistently in time. The inconsistencies between correction methods have been neglected in the practical use of these records in practice. Consequently, this work aims to provide a new strong-motion database for researchers and engineers, which has been processed by traceable and consistent data processing techniques. The record database comes from three uncorrected strong motion Chilean databases. All the records are corrected using a four-step novel methodology, which detects the P-wave arrival and introduces a baseline correction based on the reversible-jump Markov chain Monte Carlo method. The resulting strong motion database has more than 2000 events from 1985 to the date, and it is available to download at the Simulation Based Earthquake Risk and Resilience of Interdependent Systems and Networks (SIBER-RISK) project website.
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    A framework to account for structural damage, functional efficiency and reparation costs within the optimal design of countermeasures: Application to snow avalanche risk mitigation
    (2022) Favier, Philomene; Eckert, Nicolas; Faug, Thierry; Bertrand, David; Ousset, Isabelle; Candia, Gabriel; de la Llera, Juan Carlos
    In mountain areas, long-term snow avalanche risk evaluation is of paramount importance for land use planning. In avalanche-prone areas, when real estate demand is high, for instance, building protective structures may be a sensible choice for reaching a compromise between safety and development. Specifically, minimizing the risk within a quantitative framework can provide optimal defense structure configurations (size, localization, construction technology, etc.). However, existing approaches based on a proper theoretical decision-making framework still suffer from limitations making them hardly usable in practice. It is herein proposed to account for the physical, functional, and monetary dimensions of a protective measure within the assessment of total risk. Total risk, which is calculated as the mean expected loss, is quantified within a four-state system in which the failure of the dam and the failure of the dwellings to be protected are assessed with specific vulnerability relations. Bounds for the risk and subsequent optimal dam design values are quantified using minimum and maximum (min/max) functional efficiency relations of the dam. Additional assumptions regarding the functional-structural efficiency relation allow for the optimal design and corresponding minimum risk to be reached. An application is proposed with a case study from the French Alps. A comprehensive parametric study shows that the min/max bounds risk quantification is worth implementing in some cases, such as, for instance: if there is a high uncertainty of the functional efficiency of the dam, of if the assets to be protected have a monetary value. However, when the failure of the dam is unlikely to occur (due to its location or to its material resistance), it is shown that quantification of the intermediate risk without the min/max bounds approach is sufficient. In the future, the framework could be extended to many other mountain hazards (debris flows, landslides, etc.), more complex elements at risk, and even to problems going beyond the sole question of land-use planning such as traffic road regulation.
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    Conjunto de datos: SIBER-RISK Strong Motion Database
    (Datos de Investigación UC, ) Castro, Sebastián; Benavente, Roberto; Crempien de la Carrera, Jorge; Candia, Gabriel; Llera Martin, Juan Carlos de la
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    Cost-Benefit Analysis of Seismic Mitigation Measures for Wine Barrel Stacks
    (2018) Jaimes, Miguel A.; Candia, Gabriel; Favier, Philomene
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    Earthquake Simulation and Response of Wine-Barrel Stacks
    (2008) Candia, Gabriel; Llera Martin, Juan Carlos de la; Almazán Campillay, José Luis
    An analytical formulation was developed to simulate the earthquake behavior of wine barrel stacks. The model is cast using the fundamental steps of kinematics, action-deformation, and equilibrium of structural analysis. It assumes that interacting bodies are rigid and that the interaction forces between the bodies are properly represented by the use of nonlinear contact elements. Based on this theoretical model, it was possible to reproduce the overall behavior of the stack if appropriate contact element parameters are used. Contact elements are required to monitor the forces that are developed at the rack-ground and rack-barrel interfaces. It has been found that the maximum amplification of the normal stress on a body when the barrel stack is subjected to ground motions is about 3 times larger than the maximum stress due to self-weight. Furthermore, the properties of the physical contact elements were calibrated experimentally. Results of benchmark cases shows that the theoretical model is capable of representing the true collapse mechanism of the different stacks.
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    Effects of Ground Failure on Buildings, Ports, and Industrial Facilities
    (EARTHQUAKE ENGINEERING RESEARCH INST, 2012) Bray, Jonathan; Rollins, Kyle; Hutchinson, Tara; Verdugo, Ramon; Ledezma, Christian; Mylonakis, George; Assimaki, Dominic; Montalva, Gonzalo; Arduino, Pedro; Olson, Scott M.; Kayen, Robert; Hashash, Youssef M. A.; Candia, Gabriel
    Soil liquefaction occurred at many sites during the 2010 Maule, Chile, earth-quake, often leading to ground failure and lateral spreading. Of particular interest are the effects of liquefaction on built infrastructure. Several buildings were damaged significantly due to foundation movements resulting from liquefaction. Liquefaction-induced ground failure also displaced and distorted waterfront structures, which adversely impacted the operation of some of Chile's key port facilities. Important case histories that document the effects of ground failure on buildings, ports, and industrial facilities are presented in this paper. [DOI: 10.1193/1.4000034]
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    Geotechnical Aspects of the 2015 Mw 8.3 Illapel Megathrust Earthquake Sequence in Chile
    (2017) Candia, Gabriel; De Pascale, Gregory P.; Montalva, Gonzalo; Ledezma Araya, Christian Alfonso
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    Seismic vulnerability of wine barrel stacks
    (SAGE Publications, 2016) Candia, Gabriel; Jaimes, Miguel; Arredondo, César; Llera Martin, Juan Carlos de la; Favier, Philomène; Pontificia Universidad Católica de Chile. Centro Nacional de Investigación para la Gestión Integrada de Desastres Naturales
    Recent earthquakes have shown that wine barrel stacks are highly susceptible to collapse, leading to large economic losses, downtime, and longer recovery periods. This study presents a methodology using a probabilistic approach for estimating the fragility functions and economic losses in barrel stacks. The seismic response of these systems was determined from the dynamic equilibrium equations that describe the position and orientation of each element. The analysis considered ground motions scaled at different intensity levels and different barrel stack configurations; the simulations enabled reproducing the most common collapse mechanisms observed in the field and in shaking table experiments. From a statistical analysis of the results, vulnerability functions were evaluated as the probability of being within a specific damage state for a given ground motion intensity. Additional numerical simulations were performed to study the effects of the inherent uncertainty of the interface parameters controlling the dynamic response and collapse sequence of the barrel stacks. Furthermore, this methodology was used to evaluate the impact effect and improvement of a base isolation solution as a damage mitigation measure.
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    Static earth pressures on a pile supported excavation in Santiago gravel
    (2019) Lopez, Sebastian; Sanhueza, Carola; Candia, Gabriel
    Concrete soldier piles anchored in multiple levels are the most common method for supporting deep excavations in gravel. Their static design is based on limit equilibrium principles, although these procedures were originally developed for sheet piles or anchored walls on shallow excavations supporting medium-dense sand. The present study draws on the applicability of current design tools to model the static response of deep excavations in stiff gravels and their implications for design. For this purpose, the static response of an anchored pile system was evaluated with a detailed finite element model of a case study, and the results are compared with simplified hand-calculation procedures. The study unit was the 28 m deep excavation of the Beauchef Poniente building located in the fluvial deposits of the Mapocho River in Santiago. A plain strain model was developed in PLAXIS using the Hardening Soil constitutive model, with parameters determined from large-scale triaxial tests of local gravels, and the computed pile displacement were compared to actual displacement profiles measured with inclinometers. The analysis shows that the simplified procedures provide a reasonably good approximation to the computed earth pressures, internal forces on the piles, and stress in the anchors.