Study on impact resistance of steel fiber reinforced concrete after exposure to fire

The impact resistance of the steel fiber reinforced concrete (SFRC) beams after exposure to fire was studied. The SFRC beams were subjected to open flame for 120 min. After cooling to the ambient temperature, the drop-weight impact tests were conducted on the SFRC specimens. The influence of the steel fiber type and fire temperature on the impact-resistant properties was examined. The temperature time history, force time history, and reaction force-deflection curve were obtained. The peak force is discussed and the energy absorption is calculated. The results showed that the influence of steel fiber type on the impact resistance of SFRC was negligible, while the impact resistance and ductility of SFRC decreased significantly after exposure to fire. Compared with the partial fracture of the specimen at room temperature, the specimen after fire showed a more complete fracture under impact load, indicating a larger deflection and more pullout of steel fibers. This means that more friction is needed during the damage process, resulting a higher energy absorption.