A modified K&C model for concrete subjected to coupled effect of high temperature and high strain rate

The K & C model is a commonly used constitutive model for concrete that simulates its dynamic response to blasts and impacts. However, this model is calibrated using data obtained at room temperature and is therefore not suitable for high-temperature conditions. To address this limitation, we propose a new constitutive model, named the KC-HT model, which is based on extensive modifications to the commercially available K & C model. The new model incorporates a failure surface that takes into account the temperature effect, which was established through triaxial compressive tests performed at high temperatures. The plastic hardening and softening behaviors of heated concrete are also considered by a new damage determination algorithm. The KC-HT model was integrated into the ABAQUS software using the VUMAT interface for simulation purposes, and its accuracy was confirmed through both single-element simulation and numerical SHPB tests. Finally, the KC-HT model was further validated by predicting the dynamic behavior of fire-damaged RC beams. The results reveal that the KCHT model can replicate the dynamic behavior and crack morphology of concrete with different fire durations, while the K & C model is unable to take into account the temperature effect or the combined effect of high temperature and high strain rate.