Structural Performance Analysis of Simple Offshore Platforms under Ice-Vibrations in Bohai Sea

Abstract

 In China, the oil and natural gas resources of Bohai Sea are mainly marginal oil fields. It is necessary to build both ice-resistant and economical offshore platforms. So, several simple offshore oil platforms with a jacket sub-structure or with a single pillar have been deployed. There are very good economic benefits in the manufacture, installation, removal, and other aspects. These platforms were primarily designed to withstand extreme static ice forces. However, sea ice motion can induce significant vibrations for the platforms in the region. The structural ice-resistant performances have not been well developed. In this paper, combined with the field monitored data of some simple platforms in Bohai Sea, ice-induced vibrations are analyzed. The results show that even though these structures may effectively resist extreme static ice forces, the ice-induced acceleration is more significant. Then, spectral-based method is provided to analyze the fatigue life of a real simple platform. Lastly, the ice-resistant strategy is presented, which provides a basis for the design of these platforms in ice zone