Impact behavior of SFRC beams at elevated temperatures: Experimental and analytical studies

To investigate the impact response of SFRC beams at elevated temperatures, an experimental test was conducted. The impact performances of SFRC beams with fibers volume fraction of fibers of 0, 1% and 2% were tested at 25 degrees C, 400 degrees C and 600 degrees C. Moreover, a simplified analysis approach was developed to predict the high-temperature impact response of the SFRC beams. The experimental results indicate that the addition of steel fiber has an ignorable influence on the evolution and distribution of temperatures when the volume fraction of fibers is no larger than 2%. However, steel fiber can mitigate the burst of concrete during heating at 400 degrees C while has no significant influence at 600 degrees C owing to the weakening of fiber and concrete materials. Up to 600 degrees C, crack of SFRC beams subjected to simultaneous effect of fire and impact loadings can be prevented or mitigated. In addition, the incorporation of steel fibers can enhance the load bearing capacity and toughness, reduce deflection and improve recovery capacity of SFRC beams in both static and high-temperature impact loading scenarios. Due to the degradation of overall stiffness, the peak impact force would decrease at elevated temperatures. Comparing the analytical results with the test measurements, a good agreement can be noted, implying that the present simplified approach can model effectively the mechanical behavior of SFRC beams under the scenario of fire and impact loadings.