Damage identification of masonry arch bridge under blast loading using smoothed particle hydrodynamics (SPH) method

The smoothed particle hydrodynamics (SPH) method is a numerical technique used in dynamic analysis to simulate the fluid-like behavior of materials under extreme conditions, such as those encountered in explosions or high velocity impacts. In SPH, fluid or solid materials are discretized into particles. These particles interact with each other based on certain smoothing kernels, allowing the simulation of fluid flows and predict the response of solid materials to shock waves, like deformation, cracking or failure. One of the main advantages of SPH is its ability to simulate these phenomena without a fixed grid, making it particularly suitable for analyzing complex geometries. In this study, the structural damage to a masonry arch bridge subjected to blast loading was investigated. A high-fidelity micro-model was created and the explosives were modeled using the SPH approach. The Johnson-Holmquist II damage model and the Mohr-Coulomb material model were considered to evaluate the masonry and backfill properties. Consistent with the principles of the JH-II model, the authors developed a VUMAT code. The explosive charges (50 kg, 168 kg, 425 kg and 1000 kg) were placed in close proximity to the deck and pier of a bridge. The results showed that the 50 kg charges, which could have been placed near the pier by a terrorist, had only a limited effect on the piers. Instead, this charge caused a vertical displacement of the deck due to the confinement effect. Conversely, a 1000 kg TNT charge placed 100 cm above the deck caused significant damage to the bridge.