In order to determine the strength of the special deck structure of a cruise ship, this study investigates the ultimate bearing capacity of an unconventional stepped deck used in the layout of the cruise theater.

Based on the quasi-static ABAQUS method, the ultimate bearing capacity of a stepped deck is calculated and the weak positions of the structure are determined and compared with conventional deck failure modes. Meanwhile, the influence of the deck, longitudinal frame, girder web and girder panel thickness on the ultimate bearing capacity of the structure are investigated, and two structural optimization ideas are proposed: pillar reinforcement and longitudinal reinforcement.

The results show that the failure of the stepped deck mainly occurs at the boundary of the layer with the largest height difference; the ultimate bearing capacity of the stepped deck decreases significantly compared with that of a conventional deck; and the corresponding compression displacement and collapse depth increase obviously. The ultimate bearing capacity increases with the thickness of the deck, longitudinal frame, girder web and girder panels, and the improvement effect of girder web thickness is the most significant. The ultimate bearing capacity of the structure can be effectively improved by adding struts or increasing the height of the web in the weak position of the structure.

This study has great significance for the design and optimization of special decks for modern cruise ships.