Numerical analysis of residual longitudinal strength of a small-scale hull box girder under damage and bending moment

Tanker ships have a length greater than their breadth and depth and should be designed for withstanding high longitudinal bending moments of hogging and sagging. Furthermore, other situations may arise that damage the bottom or side panels. These damages can cause severe loss of structural capacity on the ultimate longitudinal bending moment. Therefore, studying this damaged structure type is useful for measuring the safety reserve through the residual strength under the bending moment. This paper analyzes a box girder on a small scale under two sequential loads. In the first step load, the box girder is indented through a spherical indenter such that the damages are applied at the upper panel, which will support the compressive loads during bending. In the second step load, a bending load by four points contact is applied to the box girder. These applied loads are used to measure the residual strength to different levels of indentations. The objective is to study the residual strength of the box girder with the intact model, a model without a central stiffener, and another without the side plate. The buckling mode of the plate is used to introduce levels of initial imperfection in the box girder plates. Numerical models are developed using the Abaqus program with shell elements, implicit solutions, and nonlinearities.