Steel shear endplate connections in fire : resistance and demand using finite element and mechanistic modeling -

Abstract

Shear endplate connections are one of the common simple beam-end framing connections used in steel structures, but their strength and deformation capacities in fire are not adequately understood. Very limited experimental studies have been conducted on full scale shear endplate beam-column assemblies. In this study, a series of finite element (FE) simulations and mechanistic modeling of steel shear endplate beam-column connections is developed to predict their behavior during fire. First, FE models are developed and validated against experimental results at ambient and elevated temperature. Second, a parametric study is conducted to investigate some major parameters that impact the behavior of shear endplate connections assemblies during a fire. This includes beam length, load ratio, initial cooling temperature, endplate thickness, endplate location, and beam depth. A comparison is also made between the performances of shear endplate, double angle and shear tab connections at elevated temperatures. The results show that although the axial load demand on the shear endplate connection is larger, the tension bolts in the shear endplate connection are more vulnerable to failure when compared to shear tab and double angle connections. Based on the FE and experimental results, a mechanistic model is proposed for the connection. The characteristics of the proposed model such as stiffness, tension, and compression are determined based on each component of the connection. The proposed model is capable of predicting the behavior of the connection and beam for different geometric properties and under varied loading conditions and elevated temperatures. This study provides guidelines for engineers to quantify and predict the fire induced thermal loads and their implications on fire design of steel framed buildings.