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This paper presents an assessment of the fragility of a reinforced concrete (RC) element subjected to avalanche loads, and more generally to dynamic pressure fields applied orthogonally to a wall, within a reliability framework. In order to obtain accurate numerical results with supportable computation times, a light and efficient Single-Degree-of-Freedom (SDOF) model describing the mechanical response of the RC element is proposed. The model represents its dynamic mechanical response up to failure. Material non-linearity is taken into account by a moment–curvature approach, which describes the overall bending response. The SDOF model is validated under quasi-static and dynamic loading conditions by comparing its results to alternative approaches based on finite element analysis and the yield line theory. Following this, the deterministic SDOF model is embedded within a reliability framework to evaluate the failure probability as a function of the maximal avalanche pressure reached during the loading. Several reliability methods are implemented and compared, suggesting that non-parametric methods provide significant results at a moderate level of computational burden. The sensitivity to material properties, such as tensile and compressive strengths, steel reinforcement ratio, and wall geometry is investigated. The effect of the avalanche loading rate is also underlined and discussed. Finally, the obtained fragility curves are compared with respect to the few proposals available in the snow avalanche engineering field. This approach is systematic and will prove useful in refining formal and practical risk assessments. It could be applied to other similar natural hazards, which induce dynamic pressure fields onto the element at risk (e.g., mudflows, floods) and where potential inertial effects are expected and for which fragility curves are also lacking.

International audience; Snow avalanches threaten more and more people and different types of structures in mountainous areas. This study focuses on a protective RC (reinforced concrete) structure consisting of an L-shaped wall. The objective of this paper is to calibrate and validate a 2D FE (Finite Element) model in order to explore the behavior of such RC structures loaded by pressure time signals caused by snow avalanche flows and to assess their vulnerability. Four concrete constitutive laws were tested to accurately describe the total collapse of the structure obtained from a pushover test carried out on a physical 1/6-scale model. Only two of four allowed converging up to the collapse of the wall. Then, the FE model was used to investigate the mechanical response of the wall under dynamic avalanche loading. The result shows that three types of structural responses can occur depending on the impulse of the loading signal: quasi-static, dynamic or impulsive. In the case of dense-snow avalanche loadings, the response of the wall can be described as quasi-static. Nevertheless, this conclusion should be interpreted cautiously. Indeed, avalanche impulses depend on many factors (type of avalanche, density, temperature, etc.) underlining that different structural responses might be expected.