Experimental study on axially loaded square hollow section T-joints under fire conditions

Abstract

This paper considers the fire resistance and failure modes of square hollow section (SHS) T-joints under axial compression at the brace end at elevated temperatures. Experimental tests on five full-scale joints with various geometries were performed. The specimens were first loaded with a constant load, resulting in a compressive reaction at the brace, then subjected to a heating process. The furnace heating followed a standard ISO 834 fire temperature curve. The specimens' temperature and deformations were measured until the specimens' failure. The results indicate that the final failure appears suddenly when the joint's temperature exceeds a critical value that is characteristic for each joint configuration. Three failure modes were observed, and the test results indicate that joint geometry affects the failure mode. A numerical study followed the experimental tests. A finite element model was created to simulate the behaviour of SHS T-joints under a brace's compression load. The model was validated and verified to obtain best representation of the joints' experimental behaviour.