This paper presents wave slamming loads on the Aasta Hansteen Spar from model test data, and it discusses analysis methodologies for extreme loads in order to derive slamming design pressures for the local and global design of the Spar hull.
A 3×3 array of slamming load transducer panels was employed to measure the horizontal wave impact loads for the 100-year and 10,000-year storms at the Aasta Hansteen field in the Norwegian Sea. The wave height and period for these storms were varied to investigate wave steepness effects on slamming loads. Three-hour simulations and as many as 20 realizations per sea state were used to capture the statistics for the slamming loads.
Gumbel distribution was used to derive extreme pressures for the local and global design at the measured direction by using various panel combinations. The short term target percentiles used in the Gumbel distribution were determined by long term analysis. The detailed long term analysis results are the subject of another paper .
The main objective of this study is to establish the extreme pressure distribution along the length of the Spar above the mean water level (MWL). The linear correlation was found between the slamming pressure coefficient and incident wave steepness and it was used to obtain the extreme pressure profile for other wave directions around the Spar hull.
The methodology presented in this paper can also be applied to slamming pressure of other platforms/floaters.