Predicting the Demand of Shear Tab Connections with Composite Beams in Fire

Abstract

Shear tab connections are one of the most commonly used simple beam-end framing connections. Simple connections are designed to resist shear forces at ambient temperature. This study aims at identifying the key parameters that affect the behavior of composite beams with shear tab connections under fire. Large axial forces are generated during a fire event due to the thermal expansion of the materials. These forces, which are not considered in the design, could lead to connection failure. In this study, finite element (FE) models are developed in Abaqus and validated against experimental data available in the literature. The strength degradation of the steel material at elevated temperatures is accounted for using retention factors. Concrete damage plasticity is implemented to model the concrete behavior at high temperatures. FE simulations are then performed to investigate the effect of different parameters on the behavior of shear tab connections in composite beams subjected to fire. The main parameters are: load ratio, concrete slab temperature, shear tab thickness, setback distance, bolt diameter, in addition to the creep in the concrete and the partial composite action. This proposed research provides more guidance on the effect of thermally induced forces and deformations of shear tab connections with composite beams. It also provides the basis for developing simple methods of analysis.