Residual stress distribution of roller bending of steel rectangular structural hollow sections

Abstract

Curved steel rectangular structural hollow sections, which have a wide range of applications in construction industry, are commonly produced by cold roller bending using pyramid-type 3-roller machine on hot finished steel hollow sections. The roller bending process induces local deformations and residual stress in the hot finished section walls. While the residual stress magnitude and distribution could have sufficient influence on the member's stability and buckling resistance, few studies have paid attention to the residual stress distribution caused by roller bending. In this paper, a proper numerical modelling procedure is employed to simulate the rolling process and reproduce the residual stress. In addition, a small scale parametric study is conducted to investigate the effects of some key roller bending parameters, including the rolling boundary conditions, the bending ratio, the steel yield stress, the thickness ratio and the shape factor, on the resulted residual stress distribution of the bended sections. Based on the results obtained from the parametric studies, a simple residual stresses model which could predict the residual stress distribution of the curved member is proposed.