Ultimate strength of box girders considering welding residual stresses

The collapse behavior of two identical box girder specimens in four-point bending is determined experimentally. The cross section of a box girder can be treated as a model of a single hull ship structure. Each specimen is composed of stiffened plate panels. Due to welding of longitudinal stiffeners and transverse frames on the plating, residual stresses and initial deflections are introduced to the structural components. The plating and the flat bar stiffeners consist of mild steel with a certified yield strength. Furthermore, nonlinear Finite Element Analyses (FEA) are performed to simulate the collapse behavior of the box girder specimens in four-point bending. The results are proposed for different numerical models considering initial deflections, welding residual stresses and initial bending due to the structural weight. The ultimate strength reduction of the box girder specimens due to initial imperfections is demonstrated. The numerical results are validated against the experimental data.