Dynamic response of concrete beams considering spatial variability of pitting corrosion damages subjected to impact loads

The spatially distributed pitting corrosion on steel rebar results in uneven loss of sections, deteriorating the material and bonding strength, thereby the resistance to dynamic loads of reinforced concrete (RC) members. Previous studies of the dynamic response of RC members under impact loads usually considered the structures in intact conditions. In the few studies that considered the corrosion deterioration, uniform corrosion damage was assumed, which might not reflect the actual corrosion damage conditions and thus might lead to inaccurate predictions of impact responses. This study numerically investigates the effects of pitting corrosion on the impact response of RC beams. The high-fidelity finite element model of corroded RC beams was established and validated in LS-DYNA. The loss of rebar and bonding interface and generation of rust expansion caused by spatially varying pittings in tensile rebar were considered. The dynamic response, reaction force, internal force, and damage mode were analysed. Effects of various factors, including corrosion degree, concrete strength, and impact energy were examined. It is found that the midspan displacement and internal force of RC beams change significantly with pitting corrosion damage under impact loads. Compared to the intact beam, the residual displacement increases by 63.9 % with an increase of corrosion degree of 20 %. Pitting corrosion also affects the impact force prominently after the first peak. The secondary peak becomes lower and the plateau phase duration becomes longer compared to the uncorroded beam. Punching shear failure is found in corroded beams, especially under high-intensity impact.