Semirigid Bolted Endplate Moment Connections: Review and Experimental-Based Assessment of Available Predictive Models

Semirigid bolted endplate moment connections are widely used in construction practice. These connections are mainly designed to resist gravity, wind, and low to moderate seismic loads. In elastoplastic designs and nonlinear system-level simulations, it is key to accurately predict or model the connection response (i.e., stiffness, strength, and ductility), rather than employing the simplified pinned or rigid idealization. Several researchers developed different empirical, analytical, and mechanical models within the past five decades to predict the connection’s full response or key response parameters. These models are generally developed and validated based on a limited experimental and/or simulation data set; hence, their accuracy and general applicability are not well established. The potential limitations of existing models arise from the complexity of flexible connections’ response due to the multitude of deforming components and the interactions between them. Accordingly, the objective of this study is to provide a comprehensive review of existing numerical models and their main assumptions and features, and to assess their accuracy. Emphasis is placed on flush and extended endplate connections, being the most commonly used connection types. The robustness of 16 numerical models was thoroughly assessed using an experimental database of more than 1,200 specimens that was recently collated. The assessment demonstrates the inaccuracy of existing models in predicting the connection fundamental response quantities, particularly the elastic rotational stiffness and ductility. The advantages and disadvantages of each model are highlighted to guide future efforts to develop more accurate models in support of performance-based engineering.