Response analysis of a truss spar in the frequency domain

The nonzero added-mass coefficients of a platform are found by using the transformation law for a second-order tensor, and the repeated application of the parallel-axes theorem. The excitation forces acting on the truss section of the platform are derived by an approach that differs from the conventional one commonly seen in the literature. The force decomposition of the Morison equation is used to add viscous effects to linear equations of motion. The nonlinear equation of motion for the heave of the truss spar is solved without any iteration in the frequency domain. The results obtained from this analysis are compared with results obtained from the conventional numerical approach and with experimental data.