Numerical investigation of side wall influence in RHS column–I-beam welded connections

Resumo

The evaluation of moment resistance, stiffness, and failure modes in welded connections between I-beams and rectangular hollow section (RHS) columns is essential for ensuring the structural integrity and performance of steel structures. However, current design codes and standard equations for estimating moment resistance do not account for all geometric parameters that influence connection behavior, such as the contribution of the side wall of the column. The equations provided by the EN 1993-1-8 and ISO 14346:2013 standards are based on the predominant failure mode of the connection. When the ratio between the beam width and the column width (β=b1/b0) is less than 0.85, failure occurs due to column frontal face plastification. For β equal to 1.0, failure is governed by column side wall yielding. Within the intermediate range of 0.85 lt; β lt; 1.0, the design standards suggest interpolating between these two failure modes. In all cases, the side wall of the column contributes to the moment resistance of the connection. In this context, the present study investigates the influence of this parameter on the structural behavior and moment resistance of uniplanar T-type welded connections. To achieve this, an investigation was conducted using finite element (FE) simulations, supported by a numerical model validated against experimental data. The analysis considered variations in the thickness (t0) and height (h0) of the hollow section side wall, as well as the thickness (t1), width (b1), and height (h1) of the beam, resulting in a total of 225 models. A comparison of the analytical formulations with the numerical results showed that the design equations tend to provide conservative estimates for the moment resistance of the connections.  The findings indicate that higher values of t0 ​ and ratios between the beam width and column width (β=b1/b0) lead to a greater influence of the column side wall on the connection behavior, resulting in increased moment resistance. Based on these observations, an equation was proposed for the case when β =1.0, which incorporates the contribution of the side walls of the column to the moment resistance of the connection, esulting in more consistent and accurate predictions.