Experimental and theoretical investigation on the fire performance of concentrically loaded recycled aggregate concrete–filled square steel tubular columns with or without fire protective coating is reported in this article. Tests of nine specimens were conducted with the variation in the recycled coarse aggregate replacement ratio, axial compressive load ratio and thickness of fire protective coating. The failure pattern, typical temperature development, axial displacement and fire resistance of the tested specimens are presented and analysed. The experimental results reveal that the temperatures of the core concrete decrease with increasing recycled coarse aggregate replacement ratio and decreasing thickness of fire protective coating under the same fire exposure time. In general, the specimens with the recycled coarse aggregate replacement ratio of 50% have a similar behaviour as the corresponding specimen with normal concrete; however, the performance of specimens with the recycled coarse aggregate replacement ratio of 100% is clearly different from the reference specimen with normal concrete. Moreover, the fire resistance of recycled aggregate concrete–filled square steel tubular columns increases with an increase in the thickness of fire protective coating and a decrease in axial compressive load ratio. A finite element analysis model was developed for simulating the performance of recycled aggregate concrete–filled square steel tubular columns exposed to fire, and the finite element analysis model was validated against the experimental results.
Numerical Study on Temperature Field of Recycled Aggregate Concrete-Filled Steel Tubular Columns Under Fire
