Examinando por Materia "risk assessment"

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    Co-evolution between structural mitigation measures and urbanization in France and Colombia: A comparative analysis of disaster risk management policies based on disaster databases
    (PERGAMON-ELSEVIER SCIENCE LTD, 2011-10-01) J. LOPEZ-PELAEZ; P. PIGEON; J. LOPEZ-PELAEZ; P. PIGEON
    This article examines the major differences between the EM-DAT and DesInventar international disaster databases, which are frequently used as the basis for designing risk reduction programs. We found that disaster prevention policies, whether they are based on EM-DAT or DesInventar disaster type, encourage an increase in urbanization especially when they are only based on structural mitigation measures. Therefore, as they cannot remove all risk of future disasters, mitigation of small to medium-scale events may lead to greater events. Our findings are based on a comparative analysis of two case studies. On the one hand, we study the impact of small events in Medellín, Colombia, while on the other hand we study the Upper Rhone basin mitigation measures, in France. © 2011 Elsevier Ltd.
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    Development of structural debris flow fragility curves (debris flow buildings resistance) using momentum flux rate as a hazard parameter
    (Elsevier B.V., 2018-05-18) Prieto, Jorge Alonso; Journeay, Murray; Acevedo A.B.; Arbelaez, Juan; Ulmi, Malaika; Prieto, Jorge Alonso; Journeay, Murray; Acevedo A.B.; Arbelaez, Juan; Ulmi, Malaika; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Societal risks associated with debris flow hazards are significant and likely to escalate due to global population growth trends and the compounding effects of climate change. Quantitative risk assessment methods (QRA) provide a means of anticipating the likely impacts and consequences of settlement in areas susceptible to landslide activity and are increasingly being used to inform land use decisions that seek to increase disaster resilience through mitigation and/or adaptation. Current QRA methods for debris flow hazards are based primarily on empirical vulnerability functions that relate hazard intensity (depth, velocity, etc.) to expected levels of loss for a given asset of concern, i.e. most of current methods are dedicated to loss-intensity relations. Though grounded in observed cause-effect relationships, empirical vulnerability functions are not designed to predict the capacity of a building to withstand the physical impacts of a debris flow event, or the related uncertainties associated with modelling building performance as a function of variable debris flow parameters. This paper describes a methodology for developing functions that relate hazard intensity to probability of structural damage, i.e., fragility functions, rather than vulnerability functions, based on the combined hydrodynamic forces of a debris flow event (hazard level) and the inherent structural resistance of building typologies that are common in rural mountainous settings (building performance). Hazard level includes a hydrodynamic force variable (FDF), which accounts for the combined effects of debris flow depth and velocity, i.e. momentum flux (hv2), material density (?) and related flow characteristics including drag (Cd) and impact coefficient (Kd). Building performance is measured in terms of yield strength (Ay), ultimate lateral capacity (AU) and weight to breadth ratios (W/B) defined for a portfolio building types that are common in mountain settlements. Collectively, these model parameters are combined using probabilistic methods to produce building-specific fragility functions that describe the probability of reaching or exceeding successive thresholds of structural damage over a range of hazard intensity values, expressed in terms of momentum flux. Validation of the proposed fragility model is based on a comparison between model outputs and observed cause-effect relationships for recent debris flow events in South Korea and in Colombia. Debris flow impact momentum fluxes, capable of resulting in complete damage to unreinforced masonry buildings (URM) in those regions are estimated to be on the order of 24 m3/s2, consistent with field-based observations. Results of our study offer additional capabilities for assessing risks associated with urban growth and development in areas exposed to debris flow hazards. © 2018 Elsevier B.V.
  • No hay miniatura disponible
    Ítem
    Development of structural debris flow fragility curves (debris flow buildings resistance) using momentum flux rate as a hazard parameter
    (Elsevier B.V., 2018-05-18) Prieto, Jorge Alonso; Journeay, Murray; Acevedo A.B.; Arbelaez, Juan; Ulmi, Malaika; Mecánica Aplicada
    Societal risks associated with debris flow hazards are significant and likely to escalate due to global population growth trends and the compounding effects of climate change. Quantitative risk assessment methods (QRA) provide a means of anticipating the likely impacts and consequences of settlement in areas susceptible to landslide activity and are increasingly being used to inform land use decisions that seek to increase disaster resilience through mitigation and/or adaptation. Current QRA methods for debris flow hazards are based primarily on empirical vulnerability functions that relate hazard intensity (depth, velocity, etc.) to expected levels of loss for a given asset of concern, i.e. most of current methods are dedicated to loss-intensity relations. Though grounded in observed cause-effect relationships, empirical vulnerability functions are not designed to predict the capacity of a building to withstand the physical impacts of a debris flow event, or the related uncertainties associated with modelling building performance as a function of variable debris flow parameters. This paper describes a methodology for developing functions that relate hazard intensity to probability of structural damage, i.e., fragility functions, rather than vulnerability functions, based on the combined hydrodynamic forces of a debris flow event (hazard level) and the inherent structural resistance of building typologies that are common in rural mountainous settings (building performance). Hazard level includes a hydrodynamic force variable (FDF), which accounts for the combined effects of debris flow depth and velocity, i.e. momentum flux (hv2), material density (?) and related flow characteristics including drag (Cd) and impact coefficient (Kd). Building performance is measured in terms of yield strength (Ay), ultimate lateral capacity (AU) and weight to breadth ratios (W/B) defined for a portfolio building types that are common in mountain settlements. Collectively, these model parameters are combined using probabilistic methods to produce building-specific fragility functions that describe the probability of reaching or exceeding successive thresholds of structural damage over a range of hazard intensity values, expressed in terms of momentum flux. Validation of the proposed fragility model is based on a comparison between model outputs and observed cause-effect relationships for recent debris flow events in South Korea and in Colombia. Debris flow impact momentum fluxes, capable of resulting in complete damage to unreinforced masonry buildings (URM) in those regions are estimated to be on the order of 24 m3/s2, consistent with field-based observations. Results of our study offer additional capabilities for assessing risks associated with urban growth and development in areas exposed to debris flow hazards. © 2018 Elsevier B.V.
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    Directional multivariate extremes in environmental phenomena
    (John Wiley and Sons Ltd, 2017-03-01) Torres, R.; De michele, C.; Laniado, H.; Lillo, R.E.; Universidad EAFIT. Escuela de Ciencias; Modelado Matemático
    Several environmental phenomena can be described by different correlated variables that must be considered jointly in order to be more representative of the nature of these phenomena. For such events, identification of extremes is inappropriate if it is based on marginal analysis. Extremes have usually been linked to the notion of quantile, which is an important tool to analyze risk in the univariate setting. We propose to identify multivariate extremes and analyze environmental phenomena in terms of the directional multivariate quantile, which allows us to analyze the data considering all the variables implied in the phenomena, as well as look at the data in interesting directions that can better describe an environmental catastrophe. Because there are many references in the literature that propose extremes detection based on copula models, we also generalize the copula method by introducing the directional approach. Advantages and disadvantages of the nonparametric proposal that we introduce and the copula methods are provided in the paper. We show with simulated and real data sets how by considering the first principal component direction we can improve the visualization of extremes. Finally, two cases of study are analyzed: a synthetic case of flood risk at a dam (a three-variable case) and a real case study of sea storms (a five-variable case). Copyright © 2017 John Wiley & Sons, Ltd.
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    Evaluation of the seismic risk of the unreinforced masonry building stock in Antioquia, Colombia
    (SPRINGER, 2017-03-01) Acevedo, A.B.; Jaramillo, J.D.; Yepes, C.; Silva, V.; Osorio, F.A.; Villar, M.; Universidad EAFIT. Departamento de Ingeniería Mecánica; Bioingeniería GIB (CES – EAFIT)
    This paper presents the development of an exposure model for the residential building stock in Antioquia (the second most populated Department of Colombia), the development of fragility functions for unreinforced masonry buildings, and estimation of building damage for two possible seismic events. Both the exposure and fragility models are publically available and can be used to calculate damage and losses due to single events, or probabilistic seismic hazard. The exposure model includes information regarding the total built-up area, number of buildings and inhabitants, building class, and replacement cost. The methodology used for the creation of the exposure model was based on available cadastral information, survey data, and expert judgment. Fragility functions were derived using nonlinear time history analyses on single-degree-of-freedom oscillators, for unreinforced masonry structures which represent more than 60% of the building stock in the region. Both seismic scenarios indicate that an event corresponding to a return period of 500 years located within the region of interest would cause slight or moderate damage to nearly 95 thousand structures, and about 32 thousand would have severe damage or collapse. This study was developed as part of the South America Risk Assessment project, supported by the Global Earthquake Model and SwissRe Foundation. © 2016, Springer Science+Business Media Dordrecht.
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    Ítem
    Evaluation of the seismic risk of the unreinforced masonry building stock in Antioquia, Colombia
    (SPRINGER, 2017-03-01) Acevedo, A.B.; Jaramillo, J.D.; Yepes, C.; Silva, V.; Osorio, F.A.; Villar, M.; Mecánica Aplicada
    This paper presents the development of an exposure model for the residential building stock in Antioquia (the second most populated Department of Colombia), the development of fragility functions for unreinforced masonry buildings, and estimation of building damage for two possible seismic events. Both the exposure and fragility models are publically available and can be used to calculate damage and losses due to single events, or probabilistic seismic hazard. The exposure model includes information regarding the total built-up area, number of buildings and inhabitants, building class, and replacement cost. The methodology used for the creation of the exposure model was based on available cadastral information, survey data, and expert judgment. Fragility functions were derived using nonlinear time history analyses on single-degree-of-freedom oscillators, for unreinforced masonry structures which represent more than 60% of the building stock in the region. Both seismic scenarios indicate that an event corresponding to a return period of 500 years located within the region of interest would cause slight or moderate damage to nearly 95 thousand structures, and about 32 thousand would have severe damage or collapse. This study was developed as part of the South America Risk Assessment project, supported by the Global Earthquake Model and SwissRe Foundation. © 2016, Springer Science+Business Media Dordrecht.
  • No hay miniatura disponible
    Ítem
    Evaluation of the seismic risk of the unreinforced masonry building stock in Antioquia, Colombia
    (SPRINGER, 2017-03-01) Acevedo, A.B.; Jaramillo, J.D.; Yepes, C.; Silva, V.; Osorio, F.A.; Villar, M.; Acevedo, A.B.; Jaramillo, J.D.; Yepes, C.; Silva, V.; Osorio, F.A.; Villar, M.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    This paper presents the development of an exposure model for the residential building stock in Antioquia (the second most populated Department of Colombia), the development of fragility functions for unreinforced masonry buildings, and estimation of building damage for two possible seismic events. Both the exposure and fragility models are publically available and can be used to calculate damage and losses due to single events, or probabilistic seismic hazard. The exposure model includes information regarding the total built-up area, number of buildings and inhabitants, building class, and replacement cost. The methodology used for the creation of the exposure model was based on available cadastral information, survey data, and expert judgment. Fragility functions were derived using nonlinear time history analyses on single-degree-of-freedom oscillators, for unreinforced masonry structures which represent more than 60% of the building stock in the region. Both seismic scenarios indicate that an event corresponding to a return period of 500 years located within the region of interest would cause slight or moderate damage to nearly 95 thousand structures, and about 32 thousand would have severe damage or collapse. This study was developed as part of the South America Risk Assessment project, supported by the Global Earthquake Model and SwissRe Foundation. © 2016, Springer Science+Business Media Dordrecht.
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    Ítem
    Modeling added spatial variability due to soil improvement: Coupling FEM with binary random fields for seismic risk analysis
    (Elsevier Ltd, 2018-01-01) Montoya-Noguera, Silvana; Lopez-Caballero, Fernando; Mecánica Aplicada
    A binary mixture homogenization model is proposed for predicting the effects on liquefaction-induced settlement after soil improvement based on the consideration of the added spatial variability between the natural and the treated soil. A 2D finite element model of an inelastic structure founded on a shallow foundation was coupled with a binary random field. Nonlinear soil behavior is used and the model is tested for different mesh size, model parameters and input motions. Historical evidence as well as physical and numerical modeling indicate that improved sites present less liquefaction and ground deformation. In most cases this improvement is modeled as homogeneous; however, in-situ measurements evidence the high level of heterogeneity in the deposit. Inherent spatial variability in the soil and the application of some soil improvement techniques such as biogrouting and Bentonite permeations will necessary introduce heterogeneity in the soil deposit shown as clusters of the treated material in the natural soil. Hence, in this study, improvement zones are regarded as a two-phase mixture that will present a nonlinear relation due to the level of complexity of seismic liquefaction and the consequent settlement in a structure. This relation is greatly affected by the mechanical behavior of the soils used and the input motion. The effect on the latter can be efficiently related to the equivalent wave period as the proposed homogenization model depends on the stiffness demand of the input motion. © 2017 Elsevier Ltd