Analyzing elastoplastic behavior and residual strength ratios in steel tubular braces under compression: a numerical investigation

The criteria for acceptance of different section types based on their section and overall slenderness have not been clearly defined by the standards. Hence, the current study delves into the elastoplastic behavior exhibited by bracing constructed from steel tubular sections. The key considerations in the practical design and ductility assessment of steel brace sections involve slenderness and the width-to-thickness ratio. Various circular and square hollow sections' braces, characterized by different slenderness and width-to-thickness ratios, are simulated using ABAQUS finite element software. Initially, the models' accuracy is confirmed through a comparison of analytical results with available experimental data. Subsequently, the investigation focuses on the impact of specific structural and material properties on the residual strength ratio of brace members. Ultimately, a set of logical relationships is proposed for predicting the residual strength ratio and target displacement of these hollow sections. Observations indicate that, in the case of stocky members, the presence of local buckling exerts a notable impact on both ductility and ultimate collapse. Conversely, in the case of slender members, the influence of local buckling on the post-buckling strength is minimal. A decrease in the slenderness parameter results in a heightened residual strength ratio. As the slenderness parameter increases, the residual strength ratio diminishes; subsequently, an elevation in member slenderness leads to an augmentation in the residual strength ratio.