Influence of Weld Modeling on the Global and Local Response of an RBS Beam–Column Connection Using Finite Element Analysis

Special moment frames (SMFs) are widely used in seismic regions because of their capacity to dissipate energy through ductile behavior. In these structural systems, the beam–column connection and its panel zone play a fundamental role in force transfer and in the overall response of the structure, while welded regions may develop localized stress concentrations that are sensitive to their numerical representation. This study comparatively evaluates the global and local response of a reduced beam section (RBS) beam–column connection using three-dimensional numerical implementations in ANSYS 2022, Abaqus 2024, and IDEA StatiCa 21.1. The ANSYS and Abaqus models were subjected to reversed cyclic loading based on the protocol prescribed in Chapter K of ANSI/AISC 341-22, while IDEA StatiCa was used as an additional numerical implementation for comparison at corresponding response levels. The detailed finite element models incorporated material and geometric nonlinearities, and the numerical responses were compared in terms of global moment capacity and equivalent von Mises stress distributions along selected weld paths. The maximum cyclic moments obtained from ANSYS and Abaqus were comparable in magnitude to the IDEA StatiCa moment evaluated at the selected reference rotation. Appreciably greater differences were observed in the local stress distributions, particularly near weld ends and geometric transition regions, where the predicted stress magnitudes, gradients, and locations of local maxima varied among the numerical approaches. These results demonstrate that agreement in global connection capacity does not necessarily imply equivalence in the predicted local mechanical response. Because the numerical implementations differ simultaneously in several modeling characteristics, the observed local differences should be interpreted as sensitivity to the complete numerical implementation rather than as effects attributable exclusively to weld modeling. Consequently, the level of numerical detail adopted for welded beam–column connections should be selected according to the response quantity of interest, particularly when localized stress demands are central to the assessment.