Wind risk assessment of structures based on Monte Carlo simulation of peak wind speeds and peak wind pressures

A reliable assessment of structural safety under wind actions needs of a probabilistic approach in order to take into account the uncertainty involved in the characterization of hazard, vulnerability and aerodynamic interaction. In this context, the concepts of Performance-Based Wind Engineering (PBWE) can be usefully adopted and a probabilistic methodology based on Monte Carlo simulation of peak wind speeds and peak wind pressures is proposed aiming at the evaluation of the annual probability of achievement a fixed limit state due to wind actions. In particular, using the Proper Orthogonal Decomposition (POD), the multi-variate random fields can be decomposed and described in a simplified way as a combination of a few low-order dominant eigenvectors (modes) generated by a Monte Carlo simulation. The methodology enables the probabilistic assessment of structural performances for a set of loading scenarios, which can simulate all possible critical events during the entire lifetime of the structure. By integrating the structural fragility and the hazard for the site, the methodology allows to estimate the annual risk associated to the achievement of a specific limit state due to wind actions and, hence, provides a tool for assessment and retrofit of existing structures and for design of new structures. The methodology can also be employed in a multihazard perspective in order to investigate the performance of a structure under different critical events and improve structural safety. In the paper, as a case study, the probabilistic methodology has been applied to an existing steel aircraft hangar.