Impact resistances of RC beams at/after high temperature: Meso-scale analysis

Impact (or blast) and fire often take place simultaneous and threaten the service life of buildings. The coupling effect of high temperature and high strain rate on the reinforced concrete (RC) structures has aroused wide concern of researchers. Based on the heterogeneity of concrete, a meso-scale numerical model was established to study the impact resistance of RC beams at/after high temperature. The strain rate effect of both concrete and steel bars and their performance degradation affected by fire and bond-slip behavior between them were taken into account. The effectiveness of numerical model was validated by comparing the results observed from the simulation and drop hammer test at room temperature. Then the impact responses of RC beams at/after high temperature was compared and analyzed. It is indicated that the proposed numerical method can effectively describe the failure mode of RC beams under the combined effect of fire and impact. RC beams at high temperature exhibit more serious damage than those specimens after cooling down at specified fire duration. The difference is widening along with the increase of fire duration.