Structural corrosion modeling for strength assessment of fixed offshore platforms for life extension study

The response of a fixed offshore platform subjected to extreme wind and wave loadings (lateral loads) under corrosion conditions is studied. The advanced simulation techniques to model corrosion damage and to perform nonlinear pushover analysis is outlined. The locations of corrosion perforations and thickness reductions can be identified based on an inspection report. A finite element model of the jacket is developed with a focus on these critical locations. The corrosion perforations can be represented as certain analytical shapes, for example, elliptical openings, at different locations, and sizes. The thickness reductions due to corrosion can be approximately modeled as shell elements with varying thickness. The platform capacity under extreme environmental loading is characterized in terms of the platform's Reserve Strength Ratio (RSR). Thus, a non-linear pushover analysis is performed to assess the strength of the corroded structure by quantifying the Reserve Strength Ratio (RSR) value. The nonlinear pushover analysis is carried out using the general finite element package Abaqus.