Numerical investigation of welding residual stresses in planar bridge trusses made of CHS steel profiles

The weld-induced residual stresses in a tubular planar K-shaped connection made of construction steel grades S355J2H and S690QH are evaluated using three-dimensional finite element models in thermo-mechanical simulation of welding process. Both lumped single-pass and multi-pass simulation alternatives are examined. The transversal component is the largest residual stress component at the gap region for all models, with values reaching the yield strength of studied steel grades. The shapes of residual stress profiles evaluated from the multi-pass models for the two steel grades show a similar trend. Although this can change when the effects of phase transformations will be considered. Considerable difference in the residual stress distribution in the gap region is observed between multi-pass welding simulation and equivalent single-pass models for both steel grades studied. For the single-pass models, the effect of using element activation on the residual stresses are negligible.