Definition of loading rate for the experimental and numerical investigation of reinforcement’s bond in concrete under impact loading

Abstract

Reinforced concrete (RC) structures are increasingly subjected to extreme loading events e.g. impacts, explosions, earthquakes. RC is a composite material. For the load transfer between its two components concrete and reinforcing steel adequate bond is required. The work presented herein provides insights into experimental testing and numerical modelling of bond behavior. It aims to create a better understanding of its changed characteristics under dynamic compared to static loading. Dynamic bond stress-slip relationships are obtained during especially designed push-in tests, since conventional pull-out tests are rather unsuitable for dynamic testing. The used experimental setup and the evaluation process are described. The influence of different slip measurement approaches on the overall bond stress-slip relationship is illustrated. In addition, the definition of loading rate based on the slip increase in time is proposed. The experimental results indicate an increase of maximal bond stress with increasing loading rate, which agrees with known results from literature. Insights into the local behavior in the vicinity of the bond zone are given by the numerical simulation in LS-Dyna. The numerical results match the experimental observations well.