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The main objective of this article is to propose a simplified methodology to assess the expected seismic damage in reinforced concrete buildings from a probabilistic point of view by using Monte Carlo simulation. In order to do so, the seismic behaviour of the building was studied by using random capacity obtained by considering the mechanical properties of the materials as random variables. From the capacity curves, the damage states and fragility curves can be obtained, and curves describing the expected seismic damage to the structure as a function of a seismic hazard characteristic can be developed. The latter can be calculated using the capacity spectrum and the demand spectrum according to the methodology proposed by the Risk-UE project. In order to define the seismic demand as a random variable, a set of real accelerograms were obtained from European and Spanish databases in such a way that the mean of their elastic response spectra was similar to an elastic response spectrum selected from Eurocode 8. In order to combine the uncertainties associated with the seismic action and the mechanical properties of materials, two procedures are considered to obtain functions relating the peak ground acceleration to the maximum spectral displacements. The first method is based on a series of non-linear dynamic analyses, while the second is based on the well-known ATC-40 procedure called equal displacement approximation. After applying both procedures, the probability density functions of the maximum displacement at the roof of the building are gathered and compared. The expected structural damage is finally obtained by replacing the spectral displacement calculated using ATC-40 and the incremental dynamic procedure. In the damage functions, the results obtained from incremental static and dynamic analyses are compared and discussed from a probabilistic point of view.

The incremental dynamic analysis is a powerful tool for evaluating the seismic vulnerability and risk of buildings. It allows calculating the global damage of structures for different PGAs and representing this result by means of damage curves. Such curves are used by many methods to obtain seismic risk scenarios at urban level. Even if the use of this method in a probabilistic environment requires a relevant computational effort, it should be the reference method for seismic risk evaluation. In this article we propose to assess the seismic expected damage by using nonlinear dynamic analysis. We will obtain damage curves by means of the incremental dynamic analysis combined with the damage index of Park & Ang. The uncertainties related to the mechanical properties of the materials and the seismic action will be considered. The probabilistic damage curves obtained can be used to calculate not only seismic risk scenarios at urban level, but also to estimate economic losses.

This article presents a methodology for an estimate of the benefit cost ratio of the seismic risk reduction in buildings portfolio at broadscale, for a world region, allowing comparing the results obtained for the countries belonging to that region. This methodology encompasses (1) the generation of a set of random seismic events and the evaluation of the spectral accelerations at the buildings location; (2) the estimation of the buildings built area, the economic value, as well as the classification in structural typologies; (3) the development of vulnerability curves for each typology; (4) the estimation of the annual average loss of the buildings portfolio in the current conditions as well as in the case of a hypothetical structural intervention. The benefit cost ratio is estimated as the difference between the estimates of the present value of these two annual average losses, divided by the retrofitting costs. This methodology has been applied to the portfolio of public schools of 14 countries ofLatinAmerica and the Caribbean, for evaluating the feasibility of the seismic risk reduction at a national scale.

Spatial variation of coda-Q (Qc) was analyzed in the Galeras volcano, located in the south western Andes of Colombia. The Qc value was calculated using the Single Backscattering model and using seismograms filtered in the band centered on 3.0 Hz. We used the estimated values as the mean attenuation that represents the total effect of the simple scattering process inside an ellipsoidal shell volume. An inversion procedure was implemented to estimate the spatial variation of Qc as function of volume fractions. Synthetic tests in 2D and 3D allow us to extend the procedure with available data from the seismological network located at the Galeras volcano. The inversion of 2855 Qc values in a grid of 8 x 8 x 8 nodes associated to 435 earthquakes and 19 stations permitted resolve the presence of two levels of attenuation anomalies which are assumed to be related to bodies of partially melted rocks, the first located around 6.0 km depth and the other one at >13.3 km depth from the summit. These bodies could be responsible for the vulcanian-type explosions as a consequence of mixture of shallow magma with depth basic magma. The shallow body seems extend along the summit and may represent the presence of plugs and fluids that are constantly fed from the deeper body and produce the actual hydrothermal activity with eruptive events. From 2002 to nowadays several eruptions has happened, e.g. at November, 2005, the volcano generated evacuation of aprox. 9000 persons from four towns around the Galeras volcano (Mapachico, Genoy, La Florida and Nariño). Along these episodes, including the one on December 6th, 2010, it looks like a large and deep magma volume is involved in this process and that more eruptive events may be expected. La variación espacial de coda-Q (Qc) fue analizada en el Volcán Galeras, localizado en el suroccidente de los Andes de Colombia. El valor de Qc fue calculado usando el modelo de retro-dispersión simple y usando sismogramas filtrados en la banda centrada a 3.0 Hz. Posteriormente, fueron usado los valores estimados como la atenuación promedia que representa el efecto total del proceso de dispersión simple dentro de una concha volumétrica elipsoidal. Un procedimiento de inversión fue implementado para estimar la variación espacial de Qc como función de las fracciones de volumen. Evaluaciones sintéticas en 2D y 3D permitieron extender el procedimiento con datos disponibles derivados de la red sismológica del Volcán Galeras. La inversión de 2855 valores de Qc en una grilla de 8 x 8 x 8 nodos asociados a 435 eventos y 19 estaciones, permitió detectar la presencia de dos niveles de anomalías de atenuación las cuales podrían estar relacionadas con cuerpos de rocas parcialmente fundidas, la primera localizada alrededor de 6.0 km de profundidad y la segunda a una profundidad >13.3 km desde la cima. Estos cuerpos podrían ser responsables de las explosiones vulcanianas como consecuencia de la mezcla de magmas superficiales con profundos más básicos. El cuerpo superficial parece extenderse en una amplia zona de la cima y puede estar relacionado con la presencia de intrusiones y fluidos que son constantemente alimentados desde el reservorio mas profundo y produce la actual actividad hidrotermal con eventos eruptivos. Desde el 2002 hasta hoy en día, varias erupciones ha ocurrido, ej. en Nov. 2005, el volcán generó la evaluación de aprox. 9000 personas de cuatro poblaciones cercanas al Volcán Galeras (Mapachico, Genoy, La Florida and Nariño). A lo largo de estos episodios, incluyendo el ocurrido el 6 de Diciembre de 2010, parece que un gran volumen de magma esta siendo envuelto en este proceso y que más episodios eruptivos podrían esperarse.

International audience; Within the frame of the SISPYR project (Seismic Information System for the Pyrenees, 2009-2011), a seismic risk evaluation of seismic risk is presented for a cross-border zone in the Pyrenees (Saint-Beat and Luchon in France and the Val d'Aran in Spain) is presented. This area has been selected because of recent seismic activity and the importance of tourism in this region. The vulnerability of existing buildings is assessed by using the vulnerability indices proposed by the RISK-UE project. This method is based in vulnerability classes defined by the EMS-98 intensity scale. Semi-empirical functions transform vulnerabilities into physical damage distributions as a function of seismic intensity. The most representative building typologies of current buildings in the area have been identified as well as their distributions within the zone. Some essential buildings have also been considered in the scenario. This information has been integrated into a GIS. The deterministic scenario considered is based on the observed and interpreted intensities of Vielha 1923 earthquake (maximal observed intensity VIII). Another scenario, based on the probabilistic seismic hazard for a return period of 475 years, is calculated taking into account the soil amplification map in for the valleys obtained from the site effects study carried out within the project. The probabilities of occurrence of direct physical damage to buildings could be used to estimate human casualties and economic losses. These results will be useful for defining prevention strategies and civil protection.

National audience; Ce travail présente un scénario de risque sismique fait sur les communes de la zone transfrontalière pyrénéenne formée par les cantons de Luchon et Saint-Béat en France et Val d'Aran en Espagne. Cette zone a été choisie par la sismicité récente et pour son fort caractère touristique. L'analyse de la vulnérabilité sismique du bâti se fait avec les indices de vulnérabilité de la méthode RISK-UE. Cette méthode définie des types constructifs basée sur les classes de vulnérabilité du bâti de l'échelle d'intensités EMS-98. A partit de ces indices de vulnérabilité et pour un niveau d'agression sismique déterminé s'estime la distribution des dégâts physiques sur le bâti avec des fonctions semi-empiriques. Les types constructifs locaux ont été identifiés ainsi comme sa distribution le long de tous les secteurs bâtis de la zone. Le scénario a été fait à partir des intensités observées et interprétées du séisme de Vielha 1923 (VIII). La répartition des états d'endommagement sur le milieu bâti sert à estimer des préjudices ou de pertes économiques. Ces données seront utiles pour la protection civile et les décideurs.

National audience; La vulnérabilité des structures soumises à des actions dynamiques est un domaine de recherche très actif ces dernières années. Les réseaux d'enregistrement du bruit de fond devraient permettent d'améliorer nos connaissances encore limitées sur le comportement dynamique des structures. Afin d'évaluer les caractéristiques modales (période propre de vibration, amortissement, modes propres de vibration) d'un bâtiment en béton armé, des mesures de vibrations ambiantes du bâtiment ont été réalisées par deux techniques différentes : mesures radar et de bruit de fond sismique.