Axial restraint forces in shear endplates of steel frames due to fire

The results of a series of finite element (FE) simulations and experimental studies are used to develop a mechanistic model that predicts the axial restraint forces in steel shear endplate beam-column connections during a fire. First, FE models are developed to predict the total force-rotation response and failure modes, and are validated against experimental results available in the literature at both ambient and elevated temperature. Second, a parametric study is conducted to investigate some major parameters that impact the behavior of shear endplate connection assemblies during a fire. This includes beam length, load ratio, fire intensity, and endplate thickness. Based on FE and experimental results, a mechanistic model is proposed for the connection of typical steel frames subjected to fire exposure. The characteristics of the proposed model such as stiffness, tension and compression forces are determined based on each component of the connection. The proposed model is capable of predicting the axial restraint forces in shear endplate connections of typical steel frames for different geometric properties, under varied loading conditions, and elevated temperatures. The results can help inform future design guidelines to account for the thermal induced forces in shear endplate connections during a fire.