Post‐fire response of aluminium alloy square and rectangular hollow sections under compression

Abstract

Aluminium alloys used in construction are strengthened through various heat treatments to be suitable for load‐bearing applications. However, this enhanced strength can be severely compromised or even eliminated when the material is exposed to the high temperatures of a fire. A structural component might thus survive a fire, but not be adequate to support its design loads for the remainder of the building's lifespan. Therefore, assessing the post‐fire response of these components is essential. This paper reports 15 axial compression tests on 6082‐T6 aluminium alloy rectangular and square hollow section stub columns. To induce the effects of fire exposure on material behaviour, the specimens were heated to elevated temperatures [200‐500°C] before being tested at room temperature. The results were then compared to those of unheated specimens. The obtained load‐end shortening behaviour, ultimate failure loads, and failure modes are reported and discussed. The results show that residual compression resistance generally decreased following exposure to 200–400°C, with only minor fluctuations beyond 400°C. EN 1999‐1‐1 and the CSM method were assessed and found to give overly conservative and scattered predictions of post‐fire compression resistance, particularly above 300°C.