Fire resistance of steel reinforced reactive powder concrete columns

Steel reinforced reactive powder concrete (SRRPC) columns have been widely used in structures due to their excellent mechanical properties. However, owing to inadequate experimental data and a lack of design basis for SRRPC columns at high temperatures, which limits the application and development of this structure in practical engineering. Five SRRPC columns with different loads were experimentally investigated at high temperatures. Additionally, 15 sets of specimens were analyzed by using numerical simulation method of thermo-mechanical coupling, and the rules of steel ratio, rebar ratio, and number of heating surfaces on the fire resistance of SRRPC columns were obtained. The test results revealed that the fire resistance decreased by 52.7% when the axial compression ratio increased from 0.2 to 0.6; The fire resistance increased by 17.79% when the steel ratio increased from 4.08% to 10.21%; The fire resistance increased by 3.24% when the rebar ratio increased from 0.83% to 2.76%; The fire resistance decreased by 28.95% when the number of heating surfaces increased from single-face heating to four-face heating. According to the variation rule of each parameter, the correlation degree of each parameter on the fire resistance was obtained, it concluded that the axial compression ratio had the highest correlation degree, followed by the number of heating surfaces, while the correlation degrees of steel ratio and rebar ratio were relatively small. A formula was proposed to predict the fire resistance of SRRPC columns, which can provide a reference for fire resistance evaluation, repair and reinforcement of SRRPC structures in fire.