Prediction of the welding distortion of large steel structure with mechanical restraint using equivalent load methods

摘要

Abstract The design dimension may not be satisfactory at the final stage due to the welding during the assembly stage, leading to cutting or adding the components in large structure constructions. The productivity is depend on accuracy of the welding quality especially at assembly stage. Therefore, it is of utmost importance to decide the component dimension during each assembly stage considering the above situations during the designing stage by exactly predicting welding deformation before the welding is done. Further, if the system that predicts whether welding deformation is equipped, it is possible to take measures to reduce deformation through FE analysis, helping in saving time for correcting work by arresting the parts which are prone to having welding deformation. For the FE analysis to predict the deformation of a large steel structure, calculation time, modeling, constraints in each assembly stage and critical welding length have to be considered. In case of fillet welding deformation, around 300?mm is sufficient as a critical welding length of the specimen as proposed by the existing researches. However, the critical length in case of butt welding is around 1000?mm, which is far longer than that suggested in the existing researches. For the external constraint, which occurs as the geometry of structure is changed according to the assembly stage, constraint factor is drawn from the elastic FE analysis and test results, and the magnitude of equivalent force according to constraint is decided. The comparison study for the elastic FE analysis result and measurement for the large steel structure based on the above results reveals that the analysis results are in the range of 80–118% against measurement values, both matching each other well. Further, the deformation of fillet welding in the main plate among the total block occupies 66–89%, making welding deformation in the main plate far larger than the welding deformation in the longitudinal and transverse girders. Highlights ? In order to predict welding deformation more precisely for the large steel structure was investigated, and the critical welding length of the specimen that affects the magnitude of welding deformation was considered. ? The critical welding length of the specimen, which was proposed by the existing research in case of the fillet welding in order to draw consistent welding deformation experimental results, was around 300?mm. ? The external constraint, which occurred as geometry of structure was changed according to assembly steps, affected welding deformation according to the magnitude of the constraint. Therefore, constraint factor was drawn from the elastic FE analysis and experiment result, and the magnitude of equivalent load by assembly sequence and constraint was decided. Without constraint, deformation was around 2–3 times different according to the degree of constraint if equivalent load was applied. ? The comparison study for the analysis result and measurement for the large steel structure showed that the analysis result was within 80–118% against measurement. ? The FE analysis result and measurement were well-matched. Further, among the deformation of the entire block, the deformation of the fillet welding joint of the main plate occupied 66–89%, which was far larger than that in the longitudinal and transverse girders.