Thermomechanical parametric studies on residual stresses in S355 and S690 welded H-sections

In order to examine and compare welding-induced residual stresses in welded H-sections of different steel grades and heat input energy, extensive parametric studies were carried out using fully calibrated and highly efficient finite element models to perform coupled thermomechanical analyses. Numerical results including temperature history and distributions, residual stress distributions and magnitudes, and force equilibrium were discussed, and comparisons were made between calibrated finite element models with different steel grades, and different heat input energy during welding. It was established that the residual stresses in S690 welded H-sections were proportionally less pronounced when compared with those in S355 welded H-sections of similar dimensions. Residual stresses in multi-pass S355 and S690 welded H-sections were shown to be significantly reduced, when compared with those in single-pass welded H-sections of similar dimensions. A simplified pattern was proposed to describe both the distributions and the magnitudes of residual stresses, and a set of formulae was also provided. It was confirmed that the residual stress pattern given in a definitive ECCS document for S355 sections was very conservative, and applicability of that pattern to S690 welded H-sections would significantly over-estimate residual stresses in these S690 sections. Hence, the proposed residual stress pattern together with the set of formulae for both S355 and S690 welded H-sections with single-pass and multi-pass welding should be adopted for accurate prediction of their structural behaviour.