The hydroelastic responses of a semisubmersible type floating airport, which consists of multiple removable units supported by column-footings in head sea are discussed. The emphases are placed on the response characteristics in short wave length range and the influence of lacking of units in this third report. Active inclination control by using air pressure in underwater columns is attempted for the case of unit lacking supposing replacement of the corroded or damaged units. Numerical analyses are performed based on the mode superposition method which combining the 3-D analyses of hydrodynamic forces (source distribution method) and mode analyses (FEM).
In this report, the calculated added mass and wave exciting force of each column are shown for understanding the interactions among columns especially in high frequency range. The calculated deflections and bending moments including higher elastic deformation modes are compared with the experimental results obtained from high frequency excitation tests. Also the responses in regular waves are calculated and compared with experiments for different conditions including unit lacking, with and without air pressure control. Finally, the influence of unit lacking on response and the effect of air pressure control are investigated consequently.