Abstract: The dynamical amplification factors based on the hull displacement for different wave directions were computed using Stokes’ 5th order wave theory, which was implemented through the ocean engineering software SACS. Then the DAF values for different wave directions were compared, which were described and explained. Some useful conclusions are got: the DAF curves are very similar for different wave angels, the differences of structural displacement acceleration are attributed to the change of difference of hydrodynamic force, the dynamical amplitude is increased because of the superimposed effects of the 1st and 2nd hydrodynamic harmonics.

Key words: self-elevating offshore platform, dynamic amplification factor, wave direction angle