Investigation of dynamic bond-slip behaviour of reinforcing bars in concrete

Under dynamic loading conditions, the bond between reinforcing bars and concrete significantly affects the structural behaviour of reinforced concrete beam-column joints. Nonetheless, limited data are available with regard to the dynamic bond-slip relationship of steel reinforcement. This paper describes the dynamic bond-slip behaviour of steel rebars in concrete. In the experimental programme, a total of 63 specimens, with different compressive strengths of the surrounding concrete and embedment lengths of reinforcement, were tested under pull-out loads. The loading rate ranged from 0.1 mm/s to 100 mm/s. Besides the tension force and the measured slip, the strain profile of reinforcement was also monitored by using strain gauges mounted to the reinforcement along its longitudinal ribs, and the corresponding bond stress was calculated based on force equilibrium. Comparisons were made between static and dynamic bond stresses to shed light on the influence of loading rate on bond stress distribution. Moreover, an analytical method was developed based on test data, and the analytical stress-slip relationship, strain and bond stress distributions were obtained by using the method. The analytical results are in reasonably good agreement with the experimental data, suggesting that the model can be used to predict the bond-slip behaviour of reinforcing bars subjected to different loading rates.