Análise numérica de colunas tubulares quadradas constituídas de aços inoxidáveis austenítico, ferrítico e duplex

Abstract

Hollow structural sections are widely used in Europe, Southeast Asia, North America, and Australia. They have high structural efficiency and present high strength when subjected to axial forces, torsion, and combined effects. Hollow sections are lightweight and have a smaller cross-sectional area than open sections, providing cost savings in fire protection, and maintenance. According to current standards, the design of stainless steel hollow structural sections is based on assumptions and analogies with the behavior of carbon steel structures, even though stainless steel exhibits significantly different behavior. Unlike carbon steel, the stress-strain curve of stainless steel does not have a well-defined yield plateau, and a nonlinear behavior can be observed even at very low-stress levels. In addition to not considering the nonlinear behavior of stainless steel for the design of hollow structures, the EN1993-1-4 uses the same buckling curve for the design of hollow structures for all three types of stainless steel studied in this dissertation: austenitic, ferritic, and duplex. This dissertation aims to study the structural behavior of austenitic, ferritic, and duplex stainless steel columns subjected to axial compression, evaluating the buckling curve according to EN1993-1-4, the Continuous Strength Method (CSM), and the SCI-P413, as well as the slenderness limits of Class 3 for compressed elements existing in the literature. The study was conducted through a parametric analysis using a nonlinear numerical model developed in the ANSYS 22 software, validated on experimental results available in the literature. Designing according to EN1993-1-4 yielded results higher than the numerical ones, with differences observed in the behavior of austenitic stainless steel compared to other types. The austenitic stainless steel columns with intermediate slenderness ratios exhibited resistances below the design curve according to EN1993-1-4. The CSM design results were also higher than the numerical values but were more accurate than EN1993-1-4, especially for stub columns. Design based on the SCI-P413 provided safer results for austenitic stainless steel but was more conservative for ferritic and duplex stainless steel. Based on the findings, a modified design method was proposed, building upon the EN1993-1-4 approach to improve column design. This method considers changes in the buckling curves, which become closer to the bucking curves proposed by SCI-. Additionally, it was concluded that the slenderness limits of Class 3 proposed in the literature for compressed elements are more suitable than those outlined in EN1993-1-4.