Optimising Reinforcement Layout for Enhanced Blast Resistance in RC Slabs: A Numerical Study

This study presents a numerical investigation into the influence of reinforcement layout on the blast response of a reinforced concrete (RC) slab subjected to a close-in explosion. The reference scenario is based on a blast test from the SEGTRANS project using a 15 kg TNT equivalent charge. A validated LS-DYNA model was used, applying the Load Blast Enhanced method and the Continuous Surface Cap Model for concrete behaviour. Forty-nine reinforcement configurations were assessed, all with constant steel mass but varying numbers of longitudinal bars and stirrups. Damage metrics such as eroded elements and internal energy absorption were used to identify an optimal layout consisting of 12 longitudinal bars and 40 stirrups, which reduced the damage volume by 5.72% compared to the original configuration (10 longitudinal bars and 29 stirrups). A further parametric study explored steel mass variations of ±10% and ±20%, applied to bars, stirrups, or both. Twelve additional models confirmed that stirrup reinforcement has a greater influence than longitudinal reinforcement in this slab configuration. To evaluate the robustness of the optimal configuration, 15 more simulations were conducted at scaled distances within the “Near field” range (0.053–0.4 m/kg^1/3), from 3 to 50 kg. These scenarios, representative of improvised explosive devices, showed a consistent reduction in damage with the optimised layout at the mid- to upper end of the scaled-distance range, but offered no improvement at its lower end due to the near-total structural disintegration of the slab.