Numerical simulation of extended end-plate connections under combined loading and bolt pretension

This study employs advanced finite element modeling to investigate the response of extended end-plate beam-to-column connections subjected to combined loading conditions, including bending moments, axial forces, and bolt pretension. The moment–rotation curve of the finite element model was validated against experimental data generated by De Lima, yielding an average error of 15.10% for the configuration with reinforcement plates at the load application point. The geometric model integrates standardized components based on DIN ( Deutsches Institut für Normung ) standards, such as bolts (DIN 933), nuts (DIN 934), and washers (DIN 125A), adhering to DIN 69 specifications for plate and column holes. An initial rotational stiffness of 10,622 kN∙m∙rad⁻¹ was achieved, with a validation error of 11.72%. This numerical approach provides a robust framework for assessing the behavior of semi-rigid joints under combined loading conditions. It also enables the identification of critical stress concentrations, supporting the use of stiffeners—as recommended by design codes—to enhance connection performance. These findings advance the understanding of semi-rigid connection mechanics and contribute to their optimization in structural engineering practice.