Fire Test on Insulated Steel Beams with Fire-Protection Coating and Fiber Cement Board

Fire safety design for steel beams is crucial in the construction of steel structures. However, there remains a significant gap in the fire resistance testing of insulated steel beams. This study focuses on full-scale experimental research examining the fire resistance performance of steel beams with varying fire protection methods, cross-sectional dimensions, and heating curves. During the tests, the furnace temperature, specimen temperature, and deflection at mid-span were measured. The test results indicated that specimens mainly failed in lateral–torsional buckling. Additionally, a markedly non-uniform temperature distribution was observed across the cross-section, and the predictions made by GB 51249-2017 were found to be unsafe. The use of fiber cement board for fire protection may be ineffective, as it tends to become brittle at elevated temperatures, making it susceptible to breakage and detachment when the beams begin to bend. Furthermore, due to potential creep deformation, specimens subjected to longer heating durations exhibited lower critical temperatures compared to those with shorter heating durations. Finally, the design method outlined in BS EN 1993-1-2 and ANSI/AISC 360-22 was evaluated against the test results, indicating an accurate prediction of these methods for specimens with shorter heating durations, but an unconservative prediction for specimens with longer heating durations due to ignorance of creep deformation.