Based on the three dimensional potential theory and finite element method (FEM), this paper presented a method for time-domain hydroelastic analysis of a floating bridge in inhomogeneous waves. A floating bridge in both regular and irregular waves, is taken as a numerical example. This method is firstly validated by the comparisons of the results between frequency domain method and presented time domain method under regular wave condition. Then the hydroeleastic responses of the floating bridge in waves with spatially varying significant wave height/peak period are presented, with the purpose to illustrate the feasibility of the proposed method. The primary results at this stage indicate that the inhomogeneity of the waves might affect the structure dynamic responses of the floating bridge in waves.

The increasing scale of the ship structure calls for hydroelastic analysis due to the growing flexibility compared with the regular ships which are regarded as rigid bodies traditionally. In the berthing stage of a barge, the motion responses and bending/torsional forces of the barge will be strongly affected by the flexible deformations of the barge itself and the wave elevation, which will be further affected by both the neighboring floating mobile harbor’s rigid motions and flexible deformations. In this paper, based on 3D potential theory, the coupling analysis model of a flexible barge adjoining a mobile harbor for the predictions of the motion responses and forces of the flexible barge is built. The effects of the flexibility of the barge, the distance between two adjacent structures, and the angles of incoming waves are numerically investigated. Wave elevation in the gap is also analyzed in order to explain the resonant peaks of the motion response.

Typically, in some side-by-side offshore operations, the speed of vessels is very low or even 0 and the headings are manually maneuvered. In this paper, the hydrodynamic responses of a two-body system in such operations under irregular seas are investigated. The numerical model includes two identical PSVs (Platform Supply Vessel) as well as the fenders and connection lines between them. A horizontal mooring system constraining the low frequency motions is set on one of the ships to simulate maneuver system. Accounting for the hydrodynamic interactions between two bodies, 3D potential theory is applied for the analysis of their hydrodynamic coefficients. With wind and current effects included, these coefficients are further applied in the time domain simulations in irregular waves. The relevant coefficients are estimated by experiential formulas. Time-varying loads on fenders and connection lines are analyzed. Meanwhile, the relative motions as well as the effects of the hydrodynamic interactions between ships are further discussed, and finally an optimal operation scheme in which operation can be safely performed is summarized.