Abstract: In view of the particularity of HYSY 161 platform’s long-term standing and immobility,this paper,referring to the requirements of the Code for Classification and Construction of Fixed Offshore Platforms and the Code for Construction and Inspection of Fixed Offshore Platforms,calculates and analyzes the frequencies corresponding to each mode based on the finite element method,and further demonstrates that the platform is safe and stable during the use of normal production operations through harmonic response analysis in different directions. Through calculation,combined with the platform layout plan,the short side of the platform is avoided to be parallel to the main wave direction of the wave,further ensuring the safety of the platform. Through spectrum analysis,it is found that under the action of random waves,the resonance phenomenon with small overall amplitude will occur in the structure at the above wave frequencies and the frequencies corresponding to the first three modes,but the structure will not be damaged after calculation. Relevant research can provide safety basis for long-term operation of HYSY 161 platform.

Key words: HYSY 161 platform, modal analysis, harmonic response analysis, spectral analysis