Methodology to Verify Residual Strength in Damaged Pontoon’s Vertical Webs Using FEM Buckling and Nonlinear Analysis

This paper introduces a methodology that can be used to verify damaged vertical webs from Semi-Submersible, Mobile Offshore Drilling Unit (MODU) as well as others offshore structures by finite element method. This paper presents an example applied to a vertical web from a triangular MODU, which consists of a triangular deck, three columns, and other supporting structure. It was subjected to damage to one of the three pontoons. The methodology isolates one of the damaged vertical webs and applies the boundary condition on the adjacent structure where the web is located. The web was modeled, using FEM in the both original and damaged condition based on information gathered from a 3D scanning system. The structure was evaluated using the American Bureau Shipping (ABS) Rules and Guides, [1] as design criteria. Based on the results of the analysis, the damaged member slightly exceeds the allowable limits. Reinforcements of the damaged areas were implemented on the damaged panels in order to reduce the stresses acceptable levels.