Numerical study and experimental tests on full-scale RC slabs under close-in explosions

Abstract

Abstract This paper investigates the response of three reinforced concrete slabs subjected to a dynamic (explosive) load at close range, through full-scale testing and its subsequent simulation with numerical models. The first slab was subjected to 1.74\xa0kg of TNT equivalent at one-meter distance and instrumented with pressure and acceleration sensors. In the second slab, the load was increased to 13.05\xa0kg of TNT equivalent while maintaining the distance; finally, the load from the second case was maintained but the distance was decreased to half a meter. The results of the three slabs were compared with respect to the concrete damage surfaces. A well-known Finite Element (FE) model with LOAD BLAST ENHANCED (LBE) tool has been used to numerically describe the slab and the explosive charge, respectively. Three different concrete material models have been used for the description of the first slab with the FE-LBE model. Numerical models adopting coupled Finite Element (FE) and Smoothed Particle Hydrodynamics (SPH) (for the charge definition) have also been developed for the same slab, including the three concrete material models and two alternatives to describe the explosive mass. After comparing the damage evolution with different material models for the concrete in the first test, the remaining tests have been simulated with the concrete model that presented the best results. In the FE-SPH models the load has been simulated with three geometries (cylinder, cube and bag) to account for the uncertainty in geometry of the explosive charge. The cylindrical charge is the best replicating the detonation pressure, the cubic charge is the best reproducing the surface damage and the bag shaped gets the best results regarding the acceleration. FE-SPH models are able to reproduce the shape of the surface damage slightly better than the classic FE-LBE, an important finding when the explosive charges are not spherical. On the contrary, the ratio of surface damage is closer to that obtained in the tests for the FE-LBE models compared to the FE-SPH models.