Proposal of a numerical methodology for the measure and optimization of structural damage in the controlled demolition of masonry arch bridges

The paper investigates the structural response of masonry arch bridges subjected to explosions, proposing a specific methodology for the measure and optimization of the structural damage in the controlled demolition of such infrastructures. Masonry bridges are structurally redundant and made of fragmented, heterogeneous materials, which respond unpredictably to explosive forces, also developing flying debris and partial failure, therefore requiring dangerous manual dismantling afterward. In this study, several numerical simulations are performed, using as a reference case study the San Marcello Pistoiese bridge (Italy), with geometric and mechanical data available in the literature. A detailed FE model is developed in Abaqus, modeling masonry elements and infill as homogeneous and isotropic three-dimensional continua and adopting the Concrete Damage Plasticity for modeling their post-elastic behavior. The effects of the detonation of spherical TNT charges on the infrastructure are modeled by means of the CONWEP approach. The position and mass of the explosive charges are varied, according to different controlled demolition scenarios. The results obtained show that the proposed methodology for optimizing the demolition procedures for masonry arch bridges, together with the general damage measurement introduced, can provide real support to professionals in the design of the controlled demolition of such infrastructures.