Experimental and numerical assessment of H500 austenitic stainless steel in steel-framed structures after fire exposure

• Mechanical and metallurgical tests on post-fire properties of H500 stainless steel. • Effect of temperatures up to 1100°C, soak time, and cooling rates were studied. • Brittle failure occurred between 700°C to 900°C due to chromium segregation. • Response of H500 in hybrid semi-rigid beam-to-column connection studied numerically. • Replacing carbon steel components with H500 results in superior post-fire ductility. This paper investigates the post-fire behaviour of H500 austenitic stainless steel and its impact on the performance of steel-framed structures after a fire. Understanding the residual properties of structural materials following exposure to elevated temperatures and subsequent cooling is crucial for assessing structural safety, enabling reuse, and avoiding unnecessary demolition. Additionally, this knowledge is essential for evaluating stability during post-fire salvage and rescue operations to ensure emergency personnel safety. A series of post-fire experiments were conducted to determine the residual mechanical properties and microstructural changes of H500 stainless steel after different heating and cooling regimes. The results indicate that specimens rapidly cooled by submersion in cold water exhibit significant degradation in elastic properties and yield strength, particularly within specific temperature ranges. These experimental findings inform a newly developed nonlinear finite element model, which assesses the post-fire residual capacity of steel-framed structures with H500 stainless steel joints. The performance is compared with high-strength carbon steel and other stainless steel grades. The findings provide valuable insights to guide future research on the post-extreme-event resilience of structural components using H500 stainless steel.