Rational Design of T-Girders via Finite Element Method

Abstract

The main configuration of ship construction consists of standard and fabricated stiffening members, such as T-sections, which are commonly used in shipbuilding. During the welding process, the nonuniform heating and rapid cooling lead to welding imperfections such as out-of-plane distortion and residual stresses. Owing to these imperfections, the fabricated structural members may not attain their design load, and removing these imperfections will require extra man-hours. The present work investigated controlling these imperfections at both the design and fabrication stages. A typical fabricated T-girder was selected to investigate the problem of these imperfections using double-sided welding. A numerical simulation based on finite element modeling (FEM) was used to investigate the effects of geometrical properties and welding sequence on the magnitude of the welding imperfections of the T-girder. The FEM results were validated with the experimental measurements of a double-sided fillet weld. Regarding the design stage, the optimum geometry of the fabricated T-girder was determined based on the minimum steel weight and out-of-plane distortion. Furthermore, regarding the fabrication stage, a parametric study with two variables (geometrical properties and welding sequence) was conducted to determine the optimum geometry and welding sequence based on the minimum welding out-of-plane distortion. Increasing the flange thickness and reducing the breadth while keeping the T-girder section modulus constant reduced the T-girder weight and out-of-plane distortion. Noncontinuous welding produced a significant reduction in the out-of-plane distortion, while an insignificant increase in the compressive residual stress occurred.

Keywords

Out-of-plane distortion / Finite element modeling / Welding residual stresses / Fabricated T-girder / Section modulus