Damage assessment and study of influencing factors in reinforced concrete beams under combined high temperature and impact

To study the impact resistance performance of reinforced concrete (RC) beams under high temperature and impact loading, a numerical model of RC beams under high temperature was established using LS-DYNA software based on existing experiments, and the validity of the numerical model was verified. Based on the numerical model, four failure modes of RC beams under high temperature and impact loading were summarized. The section damage factor D was introduced to evaluate the damage degree of RC beams under high temperature, and a predictive formula for the section damage factor in relation to impact height and temperature was fitted. The influence of temperature, beam span, impact location, and hammer shape on the impact resistance performance of RC beams under high-temperature conditions was analyzed. The results show that as the temperature increases, the mid span displacement of RC beams increases, while the impact force decreases. The larger the span to height ratio, the longer it takes for the mid span displacement to reach its peak. Under the same impact energy, the mid-span displacement caused by impact at the mid-span is greater than that caused by impact near the supports. Furthermore, hammerheads with flat contact surfaces cause greater damage to RC beams compared to those with curved contact surfaces.