Fire Tests on Unloaded HSSS Short Columns Protected by Intumescent Coating

Abstract

Fire test data on protected columns made of high strength structural steel (HSSS) are lacking but required for developing and validating analytical models for fire resistance design. To address this data gap, this paper carried out furnace tests on HSSS short columns protected by intumescent coating (IC). H and box section columns made of China grade steels of Q550, Q690 and Q890 were protected by different thicknesses of IC and subjected to the standard ISO834 fire and a realistic fire condition. Temperatures of the columns were measured, and the performances of the IC were evaluated. The study finds that the steel grade used has negligible impact on the temperature response of the steel column. The insulation performance of IC varies in different fire conditions. Under the realistic fire condition, the ICs underwent more complete reaction, generated thicker charring layers, and had better thermal insulation performance. For the investigated cases, ICs significantly reduced the temperature rise rates of the HSSS columns that the temperature rise rates stayed at 5-10°C/min after the steel temperatures reached 200°C. Furthermore, the study shows that the behaviors of IC applied on the steel members are much more complex than that of the IC applied on steel plate. Specifically, detachment of charred layers from the steel surface, a phenomenon not observed in previous studies on steel plates, was observed in this research.