A Comparison Between Rayleigh-Ritz and Finite Element Models for the Strength Analysis of Reinforced Concrete Walls Subjected to Blast Loads

The numerical modelling of structural response to impulsive dynamic loads is a topic of significant relevance in structural and safety engineering. The analysis of reinforced concrete elements subjected to blast-induced pressure waves requires models that realistically represent the spatial and temporal evolution of the loads. This study compares a modal beam model based on the Euler-Bernoulli theory, developed in MATLAB, with a finite element model implemented in ABAQUS. In the MATLAB model based on the Rayleigh-Ritz, the beam is discretized into a finite number of nodes, and the displacement field is reconstructed as a linear combination of the analytical mode shapes corresponding to a clamped-free boundary condition. External excitation is defined as a pressure wave generated by a fluid-dynamic simulation in ProSAir, representing the explosion of an equivalent TNT charge at a specified distance from the target. The overpressure values are recorded at selected target points, exported as a tabulated dataset, and used as a standard input for both MATLAB and ABAQUS models to ensure consistent loading. The comparison focuses on the peak values of key response quantities, displacements, and bending moment at the clamped end, taking the ABAQUS results as reference. The absolute error between the two predictions is used as an indicator of the modal MATLAB model’s ability to reproduce the dynamic response from finite element analysis. The aim is to define a reproducible framework for validating simplified modal models against detailed FEM simulations under realistic CFD-derived pressure loads.