Bond‐slip modeling for reinforced concrete beam‐column joints with plain reinforcement bars: Insights from numerical validation

The previous seismic events indicated the vulnerability of old reinforced concrete (RC) structures against earthquakes due to the absence of seismic detailing and capacity design specifications in such buildings. In this context, beam‐column joints (BCJ) of the existing RC structures built before the 1970s have exhibited poor structural performance under earthquake scenarios. Among the governing factors contributing to such brittle failures in BCJs, the bond‐slippage phenomenon occurring between longitudinal steel bars and concrete is one of the major contributing factors to such failures and requires further investigation since limited research has been conducted on the topic. In the present study, the results of several pull‐out tests are presented, and a numerical validation of different bond‐slip models is established. Moreover, the corresponding bond‐slip models have been employed in the numerical model of a beam‐column joint constructed with plain rebar, and the results obtained from each of the bond‐slip models are illustrated and compared with the previous experimental results of the plain rebar BCJ specimen for both monotonic and cyclic loading scenarios. Among the employed models for the BCJ, except for FIB‐CEB and Melo model cyclic results, all the other models satisfied the maximum capacity level recorded by the experimental testing for the same BCJ. The reliability of the proposed bond‐slip models is then discussed to provide further insight into the application of these models for better understanding the bond‐slip between concrete and plain reinforcement in existing RC structures.