The Smith method has been improved to calculate the ultimate strength of the semi-submersible platform during splitting and closing when considering the overall instability of the brace, in order to study the influence of the fatigue and corrosion on the reliability of the structural ultimate strength of the semi-submersible platform. A random time-varying model of the structural ultimate strength of the platform considering the effects of fatigue and corrosion is established based on the random process theory. The time-varying models of wave loads and hydrostatic loads are established for a semi-submersible platform. The time-varying reliability of the platform structure is calculated by using the parallel system method, and is compared with the annual instantaneous reliability.

The calculation of the slamming pressure for flat-bottom and flat-bottom opening structures is the hot issue of the ship structural design. The water entry of the two-dimensional (2D) and three-dimensional (3D) rigid flat-bottom structures have been simulated by using MSC.dytran. The simulation results are compared with the published experimental results and the simplified calculation method in the specification, to analyze the influence of the 3D flow on the slamming pressure of the flat-bottom structure. The influence of the opening on the slamming pressure of the flat-bottom structure is also researched according to the simulation results of the water entry of the 3D rigid flat-bottom opening structure. The results can provide reference for the structural design of the ship.

The suspended monolithic wall panel structure is a new structure of aluminum alloy hovercraft. The axial compression ultimate bearing capacity of the suspended monolithic wall panel has been analyzed by using the nonlinear finite element method. The applicability of the design formula for the stability of stiffened plates in the current "Rules for Construction and Classification of Sea-going High Speed Craft" is also discussed. The effects of the initial defect, beam stiffness, lateral pressure and residual stress on the ultimate bearing capacity of the aluminum alloy monolithic panels are investigated for the four aluminum alloymonolithic wall panel models, including one-span, five-span, strong beam and weak beam. The results show that the suspended aluminum alloy stiffened plate simulated and calculated using the ISSC defect form is the lowest. When the number of the span increases and the strength of the beam is insufficient, the lateral pressure will significantly reduce the axial compression ultimate bearing capacity of the stiffened plate, while the effect of the residual stress is relatively small.

A two-step method of non-linear finite element calculation based on one-span model is proposed to calculate the ultimate bearing capacity of the midship structure under the combined bending, shear and torsion loads. This method is then applied to calculate the ultimate bearing capacity of YOSHITERU T container ship and OSTAPENKO A box girder under the combined bending, shear and torsional loads. The proposed method has been validated and verified by comparing with the experimental results and the results from the other finite element models.

In the current study, the overall finite element analysis of an ideal Panamax passenger ship is carried out in order to examine the deformation characteristics of luxury cruise ships under the ultimate state and the influence of the initial geometrical imperfection. It is found that the deformation of the superstructure and the main hull at the midship is in the way of double plane section. A method for calculating the ultimate strength of luxury cruise ships is accordingly proposed by using the finite element model between the columns, assuming that the superstructure and the main hull bend and revolve around their respective centroids referring to the "double beam theory". The accuracy of this method is obviously improved by comparing with the conventional finite element method for calculation of ultimate strength.