Predicting Welding-Induced Transverse Shrinkage in H-Shaped Steel Beams Using a Merged Weld-Pass-Shrinkage Function-Equivalent Indirect Action Framework

On-site multi-pass welding in building steel structures often induces transverse shrinkage, affecting assembly accuracy and final geometry. Pass-by-pass thermo-elasto-plastic simulation can capture the welding process but is computationally expensive for large steel components. This study proposes an efficient framework for predicting welding-induced transverse shrinkage in H-shaped steel beams by integrating merged weld-pass modeling, a shrinkage function model, and an equivalent indirect action method. A Q355B single-sided V-groove butt-welded plate was simulated to compare the original weld-pass model with three merged schemes. The balanced three-pass scheme preserved the main mechanical response while reducing computation time from 18.863 h to 5.528 h. Based on flat-position and vertical-position plate-welding simulations, a layered shrinkage function model was developed using a plate baseline term and a geometric coupling correction term, with LOOCV RMSE, MAE, and maximum absolute error values of 0.2855 mm, 0.2424 mm, and 0.5123 mm, respectively. The predicted shrinkage was then converted into an equivalent temperature load. The equivalent indirect action method achieved an MAE of 0.1883 mm, RMSE of 0.2713 mm, MAPE of 9.2685%, Pearson coefficient of 0.9730, and R2 of 0.9042. This framework supports rapid transverse-shrinkage prediction and construction accuracy control for site-welded H-shaped steel beams.