Experimental and numerical study of high-strength aluminum alloy circular hollow sections after exposure to fire

This paper presents an experimental and numerical study on the compression resistances and local stability of high-strength aluminum alloy circular hollow section stub columns after exposure to fire. A testing program was first conducted, including heating tests, 16 post-fire material tests and 16 post-fire stub column tests. Following the testing program, a numerical modeling program was conducted, where finite-element models were developed and validated against the test results. The validated numerical models were then adopted to perform parametric studies to derive additional post-fire performance data. The obtained test and numerical data were used to carry out a comprehensive design analysis, where the existing international design standards and the Continuous Strength Method were examined. The design analysis results generally indicate that the considered international standards lead to under-estimated compression resistances for high-strength aluminum alloy circular hollow sections after exposure to elevated temperatures of 300 °C–550 °C, owing to the neglect of material strain hardening, despite a high level of accuracy for the post-fire design for the 25 °C–200 °C exposure temperature cases. The Continuous Strength Method is shown to provide greatly improved design accuracy over the existing international design standards for the post-fire design of high-strength aluminum alloy circular hollow section stub columns.