Study On Structural Safety Assessment Of Existing Offshore Platforms

One third of the ifxed offshore platforms which have been built in the world haveentered in to the evening of their design life. However, as the need for production,most of the platforms will continue to serve after they achieve the design life，whichrequires a comprehensive safety assessment of the platforms for existing situation andthe extended service life. According the safety of the platform, offshore platformstructure is decided whether or not to continue service.In the process of offshore platform installation and service, the interactions ofmarine environment and accident happening inevitably cause some damage, such as:fatigue cracks, dents, overall straight loss, corrosion damage, etc. which may causeultimate strength decrease and structures destroy. So it is vital to estimate the ultimatestrength of the damaged structures.Firstly, according to the current research of residual ultimate strength of crackedstructure, this thesis compares the structural residual ultimate strength assessment ofcracked components of offshore platform.Secondly，combined with the large-scale ifnite element software ABAQUS tomodel and analyze the residual ultimate strength of the corrosion damagedcomponents with different geometric parameters. The reasonable empirical formulafor residual ultimate strength calculation of damaged pipe is obtained.Finally, using software ANSYS model undamaged structure and structure withkinds of damage such as: cracks, dents, and corrosion damage, and the ultimatestrength value of the platform is obtained by the nonlinear analysis.Considering nonlinear material, ultimate strength of the platform structure arestudied by using ANSYS. Different damage conditions are simulated such ascorrosion，foundation eroded and brace fractured of the platform. According to the results of analysis, ultimate strength of damaged jacketplatform decrease. The cracked and corrosion damage should be paid attention to.