Numerical Simulation of Weld Induced Residual Stresses in Welded Steel Moment Connections

Structural steel members develop residual stresses due to manufacturing and fabrication processes. Depending on size and welding procedure, the magnitude and distribution of these residual stresses can vary significantly in members. Hence, it is challenging to accurately predict the magnitude and distribution of residual stresses in steel structural members and connections which can substantially affect their structural performances including global and local flange-buckling strengths, seismic performances, and low-cycle fatigue responses. Residual stresses are either ignored or a simplified distribution is assumed in the analysis and design of structural members. In a relatively recent study, the author presented a computational scheme to predict the residual stresses due to non-uniform cooling after hot-rolling of wide flange steel shapes by using a sequentially coupled thermomechanical analysis. This paper presents a numerical scheme to simulate weld-induced residual stresses in welded steel moment connections (WSMCs) by using a sequentially coupled thermo-mechanical analysis. The analysis considers the effects of phase transformation, the material heterogeneity in the heat-affected zone induced by welding, and the weld sequence. The simulation technique is validated against experimental responses demonstrating the robustness of the simulation scheme. The numerical scheme developed provides an experimentally validated computational technique for simulating multiaxial weld residual stresses in WSMCs for use in structural analysis and design of moment-resisting connections and frames.