Mechanical modeling of steel top and seat angle connections subjected to fire loading -

Abstract

The finite element (FE) simulations and the experimental results are used to develop a mechanical model to predict the axial forces and rotations of top and seat angle connections with and without web angles subjected to elevated temperatures. The model incorporates the overall connection and column-beam rotation of key component elements, and includes nonlinear behavior of bolts and base materials at elevated temperatures and some major geometric parameters that impact the behavior of such connections when exposed to fire. This includes load ratio, beam length, angle thickness, and gap distance. The mechanical model consists of multi-linear and nonlinear springs that predict each component stiffness, strength, and rotation. The beam stiffness is included in the proposed model to predict beam-column connection assembly rotation and thermal axial forces and their effect on the connection response. The proposed model is validated against experimental results available in the literature and FE simulations developed as a part of this study. The proposed model provides important insights into fire-induced axial forces and rotations and their implications on the design of steel bolted top and seat angle connections with and without web angles.