Structural Stability of Offshore Platforms

Given the hostile nature of offshore environments, ensuring the structural stability of
offshore structures is vital to their design. Acomputer program was developed for the
preliminary stability analysis ofoffshore platforms under major environmental loads.
The program output was interpreted for a minimum facility platform under extreme
storm conditions. Also, athorough framework was set for experimental studies ofthe
platform's stability using a scaled physical model.
Literature review started with gathering general background information on offshore
platforms. This included identifying their various types, their numbers worldwide and
their construction. Next, structural stability of offshore platforms was studied in
terms of the various loads exerted on offshore rigs and methods for their structural
analysis. Finally, arecently installed Minimum Facility Platform was examined as an
introduction to the case study structure.
The platform chosen as case study for the project was ahypothetical Braced Caisson
structure located at 36m of water in the North Sea. Its conceptual design and
reliability assessment under extreme storm conditions were reviewed.
Acomputer program was developed to calculate total base shear resulting from winds,
waves and currents. The program was run for the case study platform under extreme
storm conditions and results were interpreted. The breakdown of base shear by
environmental loads and structural members was studied. Valuable insights were
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The framework was defined for scale model experiments of the case study platform to
assess its structural stability. Conducting the experiments by others would then be
possible. The author built a model ofthe case study platform scaled down at 1:110.
A hydraulic flume would then replicate storm conditions at the platform site.
Expenmental setup and procedures were thoroughly specified. Procedures for
measurement using a strain gauge were identified. Finally, steps to correlate results
with platform stability were established.