Numerical Analysis of the Thermomechanical Behavior of 1.4301 Stainless Steel Beams Under Fire Conditions: Influence of Geometric Parameters on Fire Resistance

Resumo

Fires in urban areas pose a significant risk to human life and infrastructure, highlighting the need to assess structural stability and material integrity under extreme temperatures to prevent collapse. Structural failures during fire events can lead to catastrophic consequences, making it essential to understand how different elements behave under such conditions. Stainless steel, widely used in modern construction for its durability, mechanical strength, and corrosion resistance, undergoes significant reductions in strength and stiffness when exposed to high temperatures, which can lead to structural failure. Therefore, evaluating its fire performance is crucial for ensuring structural safety and designing fire-resistant buildings. To predict the performance of stainless steel in fire scenarios, numerical simulations have become indispensable, with the Finite Element Method (FEM) being one of the most effective tools. Advanced computational methods allow for detailed analysis of material behavior under thermal loads, helping to develop fire-resistant structural solutions. This study uses ANSYS software to model the thermo-mechanical response of stainless steel structures exposed to fire. Specifically, it investigates variations in mechanical properties at elevated temperatures and their influence on overall fire performance. The methodology employs Geometrically and Materially Nonlinear Imperfection Analysis (GMNIA) for both static and fire simulations, along with nonlinear transient temperature analyses. A comprehensive parametric study was conducted to assess the impact of geometrical section dimensions on the strength of 1.4301 austenitic stainless steel beams, considering seven different transverse sections exposed to fire on three sides and subjected to a four-point bending load condition. The results indicate that thickness and width significantly influence temperature distribution, affecting structural stability and fire resistance. For the RHS 180x100x5 section, at a load level of 0.2, the simulation time was 55 minutes, while at load levels of 0.4 and 0.6, the maximum supported time decreased to approximately 27 minutes and 15 minutes, respectively. These findings reinforce the importance of geometric parameters in determining the fire resistance of stainless steel beams. The study provides valuable insights for optimizing structural design, improving fire safety, and contributing to the development of safer and more resilient buildings.