Characterizing the bond-slip behaviours of steel bar in concrete under dynamic loading using a modified high-speed tensile testing device

Abstract

This study conducted pullout tests to characterize the bond-slip behaviors of plain steel bars in concrete under dynamic loading. In the pullout tests, we adopt the high-speed tensile testing device to measure the bond-slip curves for plane steel bar and concrete at dynamic strain rate varying from 3×10-1 to 103 mm/s. By increasing the strain rate, the results show a significant increase in bond strength at the interface of steel bar and concrete. We also observe that the failure mode generally changes from pullout to splitting with increasing strain rate. The strain-rate effect on the tensile strength of concrete and steel bar is further evaluated by comparing dynamic increase factor (DIF) with strain rate. The results show a significant increase in DIF at high strain rate compared with that at low strain rate, suggesting a more pronounced strain-rate effect on bond strength at high strain rate.