Damage Response of Polyurea-Coated Reinforced Concrete Beams Under Continuous Blast Loads: Influence of Number of Blasts on Damage Effect with Equal Charge Mass

The structural stability of reinforced concrete (RC) beams under extreme loads has always been a popular research topic in structural engineering. In this study, the damage characteristics and dynamic responses of polyurea-coated RC beams under continuous blast loads were investigated. A finite element model was developed and experimentally calibrated. The effects of different numbers of blasts of equal-mass charges on RC beams were analyzed. The damage modes of the specimens with different numbers of blasts were obtained and the residual stiffness of the RC beams after the blasts was evaluated. The results showed that the polyurea coatings significantly enhanced the blast resistance of the RC beams and effectively reduced the damage effect and the risk of cumulative damage. Under the loads of equal mass charges, the larger the mass of a single load and the smaller the number of blasts, the more serious the damage to the RC beam. Compared to four cumulative explosions with a single-charge mass of 100[Formula: see text]g, the mid-span displacement and mid-point velocity of the RC beam under a single explosion with a charge mass of 400[Formula: see text]g increased by 40.47% and 47.44%, respectively. The residual stiffness index (RSI) assessment revealed that the residual stiffnesses of the RC beams decreased with the increase in the mass of a single charge and the number of blasts, and the damage level showed a decreasing trend.