A Unified Mechanical Model for Fire Design of Simple Steel Connections

Abstract

The objective of this study is to develop a unified mechanical model that can be considered as a practical tool for designing steel connections for professional structural-fire engineers in the U.S. The proposed model is capable of predicting the behavior of two widely used simple steel connections (shear tabs and double angles) when subjected to fire temperatures. It incorporates the connection rotation of key component elements, and the nonlinear behavior of both bolts and base materials at elevated temperatures. The model includes linear and nonlinear springs, which predict the strength, stiffness, and rotational capacities of each connection component. The proposed model is validated against experimental results available in the literature under steady-state temperature analysis. The model covers all possible limit states and governing failure modes under different loading and temperature conditions. The model can be used to develop fire design guidelines for simple beam-column connections in fire.