Nonlinear SDOF model for dynamic response and fragility analysis of steel plates under blast loads

Understanding the response of structural elements to blast overpressure, particularly in terms of displacement and failure thresholds, is essential for effective design and safety assessments. This study introduces a novel Single Degree of Freedom (SDOF) model developed by the authors to predict the dynamic behavior of steel plates subjected to blast loads. The proposed SDOF model was validated against experimental data from the literature and finite element analysis (FEM) simulations, demonstrating its reliability in predicting maximum displacements while maintaining computational efficiency. The validated model was used for parametric studies to investigate the influence of plate thickness, blast load intensity, and aspect ratio on the dynamic response of steel plates, highlighting the sensitivity of mid-span displacement to these parameters. A key application of the developed SDOF model is the efficient generation of fragility curves. Using a Monte Carlo approach, with the explosive mass treated as a stochastic variable, the probability of exceeding specific damage thresholds under various blast scenarios was assessed. The results confirm that the SDOF model provides a practical and accurate tool for evaluating structural performance and resilience, offering critical insights for the design of steel plates under extreme dynamic loading conditions.