Fire performance of edge and interior circular steel-reinforced concrete-filled steel tubular stub columns

The steel-reinforced concrete-filled steel tubular column (SRCFT) is a new form of composite columns. Before widely accepted in engineering practice, its fire behaviour shall be fully understood. Four representative circular SRCFT stub columns were built and tested to failure under ISO fire herein. The tests explored the effect of reinforced steel, the internal or external heating condition and load ratios. The experimental results indicated that the inserted section steel significantly improved the fire resistance of circular SRCFT columns. The non-uniform fire condition did not produce a detrimental effect on the fire response of the specimen. The numerical model was developed and validated against the experimental results. Then a parametric study was present to evaluate the effect of load level, eccentricity and heating conditions. A comparison was made to check the accuracy of a widely accepted design method. The comparison indicated the design method was generally 36% conservative for axially loaded condition and 25% un-conservative for eccentrically loaded condition.