Damage features and dynamic response of RC beams under blast

• We investigated RC beams under blast loading through experiments.
• The damage features of RC beams with different stirrup ratios are studied.
• The dynamic response of RC beams is studied through simulations.
• A formula on deflection, scale distance and stirrup ratio was obtained.

Through experimental and numerical study, the anti-blast performance and damage characteristics of reinforced concrete beams with different stirrup ratios were analyzed. Two sets of specimens with two different stirrup ratios were tested under blast loading, with two explosive masses (0.99 kg and 1.46 kg TNT) considered in each set. Large inelastic deformation and local spallation were observed in all tests. The increase of TNT charge mass is shown to gradually change the damage degree of RC beam. And with an increased stirrup ratio, the deflection, the spall radius and especially the spall depth were observed to decrease. The core concrete of the low stirrup ratio specimens was all damaged to some extent. The experimental results indicate that the stirrup ratio has significant influence on the survivability of RC beams when subjected to blast loading. Numerical studies were implemented using the explicit nonlinear finite element analysis software LS-DYNA. The dynamic response process of RC beams under blast was obtained and the generation mechanism of spallation was analyzed. Four additional numerical models with different stirrup ratios were built and implemented on blast simulations. The results demonstrate that the deflection thickness ratio of RC beam is inversely proportional to the scale distance and the stirrup ratio. Based on the above analysis, an empirical expression on deflection thickness ratio was obtained which considered both the scale distance and the stirrup ratio.