A Simplified Approach to Evaluate Ultimate Strength and Deformation Capacity of Bolted T‐Stubs tied to Rigid Bases

Abstract

The mechanical response of bolted T‐stub components plays a key role in the nonlinear performance of steel joints. While existing analytical formulations provide accurate predictions for bending‐controlled collapse mechanisms, configurations connected to rigid supports and subjected to large displacements may exhibit additional deformation modes that are not fully captured by classical models. In highly ductile cases, bolt–hole contact can occur before the attainment of the flexural ultimate condition, leading to a transition from bending‐controlled to shear‐influenced behaviour. This paper extends a previously developed closed‐form framework by introducing an additional collapse mechanism, denoted as MEC‐1S, specifically accounting for bolt–hole contact and subsequent shear interaction. The ultimate resistance associated with this mechanism is derived from equilibrium conditions based on the corresponding kinematic model, and a simplified expression is proposed to evaluate the related displacement capacity as a function of bolt–hole clearance and bolt shear ductility. A comprehensive parametric study involving 210 configurations was carried out using an advanced nonlinear mechanical model. The comparison between predictive formulas and numerical results shows satisfactory agreement, with average strength and displacement ratios equal to 1.07 and 1.03, respectively. The proposed extension improves the physical consistency of the model in large‐displacement regimes while preserving its simplified and design‐oriented character.