Identification of optimum reinforcement detailing using tuned CDP parameters in RC beam under drop-weight impact

Abstract

A numerical investigation has been carried out in this study to investigate the dynamic response of RC beam subjected to low velocity impact. Concrete damage plasticity (CDP) model including the strain rate effects is used in this study to simulate material behavior of concrete. Sensitivity analysis is performed to understand the influence of crucial CDP parameters and to obtain tuned CDP parameters of concrete for accurate prediction. Then an attempt has been made to identify and benchmark effects of reinforcement detailing parameters in effective impact resistance of reinforced concrete beams for inclusion in design requirement as per specific performance level sought. The results obtained from the present model have been coherently validated with the established experimental results. Energy distribution in major dissipating mechanisms like plastic flow (plastic dissipation energy, PD), crack surface nucleation (damage dissipation energy, DMD) and global failure modes are investigated to quantify the exclusive effects of both flexure and shear reinforcement details. It is observed that tensile reinforcement helps to reduce the permanent plastic displacement and flexure cracks. But it is not that much effective for overall damage prevention and specifically the shear cracks. Stirrups spacing in stead of diameter is found to be the controlling details for reducing DMD. Hence the use of optimum tensile reinforcement along with closely spaced stirrups is found to be the most effective way to improve structural behavior under impact loading and present framework can effectively quantify the effects of such detailing.