Numerical Investigation on Steel T-stub Connection Considering Prying Action at Elevated Temperatures

Abstract

Bolted endplate connections are widely employed in steel structures to connect beams to columns, since they are easy to fabricate and provide efficient structural performance. The T-stub connection model is commonly used to represent the tension zone components in the bolted endplate connections. Prying action is a crucial factor influencing the overall behavior of the T-stub connection model. Existing design equations consider the effect of prying force on the behavior of the steel T-stub connection model at ambient temperature. However, the material properties, such as the yield strength, ultimate strength, or elastic modulus, decrease, leading to the remarkable loss of stiffness, strength, and potential failure modes of steel connections at high temperatures. Therefore, accurate modelling of T-sub connections, including the prying effect, at elevated temperatures, is crucial to ensure the integrity of the steel structures in a fire. This study investigates the overall behaviors of the steel T-stub connection model affected by prying action at elevated temperatures via the finite element (FE) method, strictly considering nonlinear material, geometric, contact, and friction in modelling. The FE model is validated using the experimental results conducted by others, in which the failure modes are determined by comparing the stress and equivalent strain at the monitor point in the FE models. The prying forces exerted by the endplate are numerically calculated based on the bolt’s forces and the applied load. Finally, a parametric analysis is performed thoroughly to investigate the effect of temperature, bolt diameter, and T-stub section on the behavior of the steel T-stub connection model at elevated temperatures. The results show that temperature and bolt diameter are the most influential parameters in the behavior of the steel T-stub connection model with prying action at elevated temperatures.