Post-fire capacity of aluminium alloy rectangular hollow sections under compression

This paper presents experimental and numerical investigations on the post-fire residual capacities of aluminium alloy rectangular hollow sections under compression. A testing programme was firstly carried out, including heating tests, seven post-fire material tensile coupon tests and fourteen post-fire stub column tests. Following the testing programme, a numerical modelling programme was conducted, where the finite-element models on the post-fire stub columns were developed and validated against the test results. The validated numerical models were then used in parametric studies to derive more post-fire capacity data. Based on the test and numerical data, a design analysis was performed, where the applicability of the current international design codes to the post-fire design of aluminium alloy rectangular hollow sections was evaluated. The results reveal that all considered design codes generally lead to conservative residual compression capacity for post-fire aluminium alloy rectangular hollow sections, especially for those after exposure to the temperatures of 250 °C to 500 °C, owing to the neglect of post-fire material strain-hardening effect. Then, the continuous strength method that considers the material strain-hardening effect, was evaluated and found to result in significant design improvement.