New Component-Based Model for Single-Plate Shear Connections with Pre-tension

摘要

Although simple shear connections are typically idealized as perfectly pinned, the actual resistance of the gravity framing system to flexural and axial loads can be critical in evaluating the robustness and stability of steel buildings subjected to extreme loads such as earthquakes, fire, and column loss. There are several key reasons for including more realistic connection behaviors in the design and analysis of steel buildings for extreme loads: (ⅰ) the gravity connections may develop large localized deformations under combined flexural and axial loading, potentially precipitating their failure (e.g. due to local buckling, fracture of the bolts, etc.), (ⅱ) the gravity connections provide critical lateral bracing to the columns, and failure of connections could lead to global instability (potentially resulting in disproportionate collapse), and (ⅲ) accurately accounting for contributions from the gravity system in design could effectively reduce the demands on the lateral load-resisting system, thus reducing costs. In order to include contributions from the steel gravity frames in structural analysis and design, validated and computationally efficient analysis tools are needed. This paper describes a component-based model for single-plate shear connections that includes the effects of pre-tension and accommodates both standard and slotted holes, accounting for deformations associated with bolt slip, bolt bearing, and bolt shear. The model also accounts for load reversals and pinching effects associated with hysteresis, thus providing the capability to model the connections under arbitrary in-plane load histories. Validation cases show that the model is capable of simulating connection response under both earthquake and column removal loading.