FE dynamics and damage modeling of a masonry arch bridge subjected to close-range explosions in controlled demolition scenarios

This study investigates the structural response and the explosion- induced damage for masonry arch bridges under blast loading, with the goal of optimizing explosive charge placement in controlled demolitions. Due to their structural redundancy, masonry arch bridges exhibit nonlinear behavior under extreme dynamic loads, leading to unpredictable responses. Consequently, explosive demolition presents safety risks, including uncontrolled debris projection and incomplete collapse mechanisms, which may require hazardous post-blast dismantling. A comprehensive numerical analysis is performed using the San Marcello Pistoiese bridge (Italy) as a case study, with detailed geometric and mechanical data available in the literature. A three-dimensional finite element model was developed in Abaqus, in which masonry and infill material are modeled as homogeneous, isotropic solids. The Concrete Damage Plasticity (CDP) formulation is employed to describe the post-elastic behavior, including stiffness degradation and damage. Blast loading was simulated using the CONWEP approach, based on the empirical relations by Kingery and Bulmash (1984). Different demolition scenarios are examined, by varying the mass and position of the explosive charges. The numerical results have provided insights into damage evolution, collapse mechanisms, and effectiveness of alternative blasting configurations, facilitating the optimization of demolition strategies while accounting for the structural characteristics and uncertainties inherent in masonry arch bridges.