Assessment of Residual Stresses due to Cold Bending Structural Steel Girders using Finite Element Modeling

Cold bending is sometimes used for curving structural steel girders in horizontally curved structures. Although the process is simple and cost effective, it is not widely adopted yet due to the ambiguity in estimating residual stresses induced at the end of the bending process that could be relatively high. This paper focuses on assessing the magnitude of these residual stresses for a proprietary cold curving technique using nonlinear finite element analysis. For this purpose, a three-dimensional non-linear Finite Element model is developed for an IPE 600 standard symmetrical steel shape using shell elements and MSC-SimXpert analysis software. In the finite element model, bending (post-yield) loads are applied at specified intervals along the girder length, starting at one end of the girder and moving to the other end and the curved shape develops as a series of short straight segments as a function of the induced residual deformations. The effect of varying some of the key parameters (e.g. magnitude of applied loads, loading sequence and spacing between end supports) on residual stresses is then investigated and recommendations are suggested for inducing practical ranges of curvatures with acceptable limits for residual stresses.