Small and frequent disasters due to climate variability and change: an accumulative development problem

Small disasters contrary to the extreme and extraordinary events are very often not visible at the national level and their effects are not relevant from a macro-economic point of view. They usually affect the livelihoods of poor people in rural areas and small municipalities, perpetuating their level of poverty and human insecurity as factors of social vulnerability. Risk regarding small disasters frequently is not considered as relevant, nevertheless due to their accumulated impact and recurrence, they are a social, economic and environmental problem with big implications. These events are primarily related to persistent hazards such as landslides, avalanches, floods, forest fires, droughts and so on resulting from socio-ecological processes associated with climate variability, change and environment deterioration.Peer ReviewedPostprint (published version

The economic and social effects of small disasters: revision of the local disaster index and the case study of Colombia

Analysis of small disasters illustrates how these frequent events, usually as result of the climate variability, increase difficulties for the local development and entail a serious problemfor the development of a country as a whole. These disasters, contrary to the extreme and extraordinary events, are not visible at the national level very often and their effects are not relevant frommacro-economic point of view. Small disasters usually affect the livelihoods of poor people in rural areas and small municipalities, perpetuating their level of poverty and human insecurity as factors of social vulnerability.On the other hand, in urban centers, small andmoderate disasters have allowed having a light of the city zones that historically have presented the greatest vulnerability levels.The main objective of this paper is to present the revisionmade to themethodology of the LocalDisaster Index (LDI),developed in the framework of the Program of Indicators for Disaster Risk Management in the Americas. The LDI in the new version illustrates that the accumulative impactmay be highly significant at the local level and, consequently, to the national level fromsocial point of view. In addition, the paper presents the results of the evaluation of the proneness of Colombia to small scale and chronic disasters and the type of impact they have to the local development and to the country from an aggregated point of view. Such analyses have detected the spatial variability and dispersion of vulnerability and risk in the country as a result of events that rarely enter the international or even national disaster databases,but which pose an accumulative development problemfor local areas and, given their overall probable impacts, for the country as a whole.Postprint (published version

FLEXIBILITY-BASED LINEAR DYNAMIC ANALYSIS OF COMPLEX STRUCTURES WITH CURVED-3D MEMBERS

A fexibility-based formulation of a new mass matrix for the dynamic analysis of spatial frames consisting of curved elements with variable cross-sections is presented. The main characteristic of such formulations is the exact equilibrium of forces at any interior point, with no additional hypotheses about the distribution of displacements, strains or stresses. Accordingly, the derived element mass matrix takes into account the exact sti ness and mass distribution throughout each element. In validation tests, results obtained with this method are compared with those obtained by other numerical or analytical formulations, showing the accuracy of the proposed method. The comparison of experimental results for a multispan arch bridge subjected to a dynamic load with those achieved by means of the proposed method are nally included to illustrate its eciency in the treatment of complex structures

Hybrid loss exceedance curve (HLEC) for disaster risk assessment

Taken into account that the natural hazard risk is a contingent liability and, therefore, a sovereign risk for national governments, it is important to assess properly the potential losses to design a suitable risk reduction, retention and transfer strategy. In this article, a disaster risk assessment methodology is proposed based on two approaches: on the one hand, the empiric estimation of losses, using information available from local disaster databases, allowing estimating losses due to small-scale events and, on the other hand, probabilistic evaluations to estimate losses for greater or even catastrophic events, for which information usually is not available due to the lack of historical data. A ‘‘hybrid’’ loss exceedance curve is thus determined, which combines the results of these two approaches and represents the disaster risk in a proper and complete way. This curve merges two components: the corresponding to small and moderate losses, calculated using an inductive and retrospective analysis, and the corresponding to extreme losses, calculated using a deductive and prospective analysis. Applications of this risk assessment technique are given in this article for eleven countries

La vulnerabilidad en el marco de la sostenibilidad fiscal de los países

El desastre y el riesgo son problemas sociales, económicos y ambientales ligados a procesos de acumulación de vulnerabilidades, que a su vez son producto de modelos de crecimiento no sostenibles, es decir, los desastres son problemas de desarrollo o riesgos no manejados y, por lo tanto, acciones de identificación y reducción de riesgos, respuesta a desastres y transferencia del riesgo son necesarias para la planificación; ineludiblemente, la gestión de riesgos es transversal al desarrollo. Desde la perspectiva económica, los desastres pueden generar un déficit financiero dada la necesidad de recursos para restituir los elementos afectados, por lo que se debe contar con una política pública de gestión financiera, que, aunque no es una medida de mitigación, porque no reduce el daño, es un incentivo para la prevención y garantiza la financiación y eficiencia en las actividades de reconstrucción. Este artículo describe el modelo del Índice de Déficit de Desastres (IDD) y los resultados para los países de las Américas con el fin de orientar la toma de decisiones desde la perspectiva macroeconómica de los gobiernos. El IDD mide el riesgo del país desde la perspectiva de la sostenibilidad fiscal de acuerdo a posibles eventos catastróficos. El IDD captura la relación entre la pérdida económica que un país podría sufrir cuando un evento catastrófico ocurre y la disponibilidad de fondos para hacer frente a la situación. Para calcular las pérdidas potenciales, en el modelo, al igual que en la industria aseguradora, se define un nivel de referencia para estimar las pérdidas factibles (métricas como la pérdida máxima y anual esperada) basado en los impactos críticos durante un período de exposición dado; para la resiliencia económica, el modelo calcula la capacidad financiera del país para enfrentar la situación. El acceso a recursos tiene limitaciones y costos que deben considerarse, como los valores factibles de acuerdo a las condiciones macroeconómicas y financieras del país.Peer ReviewedPostprint (published version

PROBABILISTIC ASSESSMENT OF THE SEISMIC PERFORMANCE OF STEEL BUILDINGS DESIGNED ACCORDING TO THE LRFD SPECIFICATION

Seismic regulations and building codes experienced major advances in the last decades. Nevertheless, current trends in earthquake engineering are the assessment of the computational procedures provided by such design rules, by using probabilistic techniques, in order to test the anticipated levels of reliability and performance of the structures. While some consideration is given in codes to the uncertainties associated to the seismic action, no probabilistic requirements are posed on the responses, which determine the final design. Consequently, the risk associated to the design formulas remains unknown. The objective of this chapter is to study whether steel buildings designed and constructed according to the Load and Resistance Factor Design (LRFD) specification for Structural Steel Buildings, reasonably meet the probabilistic requirements on structural member safety applying non-linear dynamic analyses and Monte-Carlo techniques. Starting from a specific low-rise braced frame steel building existing in Manizales, Colombia, we also analyze mid-rise and high-rise braced frame buildings. Similar low- mid- and high-rise Moment-resisting frame buildings are also studied. For each building we performed more than ten thousand dynamic simulations, covering a wide range of combinations of demand and strength. In this way, we determine the exceedance probability of the construction capacity and we verify the safety and reliability of the structural members of the buildings. In the analysis of demand, we consider the probabilistic variation of the vertical gravity loads as well as of the seismic horizontal ones. The analyses of the strength of the studied buildings take into account the uncertainties and probability distributions of several parameters as: the yielding strain, the elasticity modulus, the cross-sectional area and their inertia moments. The analysis shows that in the cases here analyzed, but especially in moment-resisting frame buildings, the uncertainties in the input parameters may lead to significant failure probabilities. We conclude that braced frame steel buildings fulfil the seismic safety requirements while moment-resisting frame buildings would require a safety factor of about 2.7 for the column anchorages to the foundations

Cálculo y diseño sismorresistente de edificios: aplicación de la norma NCSE-02

Postprint (published version

Herramienta computacional para la evaluación post-sísmica de daños en edificios

En este artículo se desarrolla un método y una herramienta computacional orientada a apoyar la evaluación de daños y de la seguridad de los edificios después de sismos fuertes. Los datos de entrada del programa de computador corresponden a información subjetiva e incompleta del estado del edificio, obtenida por profesionales posiblemente inexpertos en el campo de la construcción. Los niveles de daño de los componentes estructurales normalmente son descritos por calificaciones lingüísticas que pueden ser adecuadamente procesadas con técnicas de inteligencia computacional basadas en sistemas neurodifusos. Estas técnicas facilitan la realización de las complejas y urgentes tareas de toma de decisiones de los ingenieros en relación con la ocupación de los edificios después de un desastre sísmico. El sistema híbrido neuro-difuso, descrito en este artículo, está basado en una red neuronal de tres capas artificiales unidireccionales especiales y una base de reglas de lógica difusa. Este sistema es una herramienta de especial utilidad durante la fase de respuesta a emergencias, que facilita las decisiones de habitabilidad y reparabilidad de los edificios. Para ilustrar su aplicación se incluyen ejemplos de aplicación del programa para tres clases diferentes de edificios.Postprint (published version

Multi-directional dynamic model for traumatic brain injury detection

Traumatic brain injury (TBI) is a complex injury that is hard to predict and diagnose, with many studies focused on associating head kinematics to brain injury risk. Recently, there has been a push towards using computationally expensive finite element (FE) models of the brain to create tissue deformation metrics of brain injury. Here, we developed a 3 degree-of-freedom lumped-parameter brain model, built based on the measured natural frequencies of a FE brain model simulated with live human impact data, to be used to rapidly estimate peak brain strains experienced during head rotational accelerations. On our dataset, the simplified model correlates with peak principal FE strain by an R2 of 0.80. Further, coronal and axial model displacement correlated with fiber-oriented peak strain in the corpus callosum with an R2 of 0.77. Using the maximum displacement predicted by our brain model, we propose an injury criteria and compare it against a number of existing rotational and translational kinematic injury metrics on a dataset of head kinematics from 27 clinically diagnosed injuries and 887 non-injuries. We found that our proposed metric performed comparably to peak angular acceleration, linear acceleration, and angular velocity in classifying injury and non-injury events. Metrics which separated time traces into their directional components had improved deviance to those which combined components into a single time trace magnitude. Our brain model can be used in future work as a computationally efficient alternative to FE models for classifying injuries over a wide range of loading conditions.Comment: 10 figures, 3 table

Role of mitochondrial raft-like microdomains in the regulation of cell apoptosis

Lipid rafts are envisaged as lateral assemblies of specific lipids and proteins that dissociate and associate rapidly and form functional clusters in cell membranes. These structural platforms are not confined to the plasma membrane; indeed lipid microdomains are similarly formed at subcellular organelles, which include endoplasmic reticulum, Golgi and mitochondria, named raft-like microdomains. In addition, some components of raft-like microdomains are present within ER-mitochondria associated membranes. This review is focused on the role of mitochondrial raft-like microdomains in the regulation of cell apoptosis, since these microdomains may represent preferential sites where key reactions take place, regulating mitochondria hyperpolarization, fission-associated changes, megapore formation and release of apoptogenic factors. These structural platforms appear to modulate cytoplasmic pathways switching cell fate towards cell survival or death. Main insights on this issue derive from some pathological conditions in which alterations of microdomains structure or function can lead to severe alterations of cell activity and life span. In the light of the role played by raft-like microdomains to integrate apoptotic signals and in regulating mitochondrial dynamics, it is conceivable that these membrane structures may play a role in the mitochondrial alterations observed in some of the most common human neurodegenerative diseases, such as Amyotrophic lateral sclerosis, Huntington's chorea and prion-related diseases. These findings introduce an additional task for identifying new molecular target(s) of pharmacological agents in these pathologies