This study analyzes the influence of lateral loads on the ultimate strength and collapse modes of stiffened panels subjected to combined loads.

Nonlinear finite element software ABAQUS is used to set up numerical models and perform numerical simulations under combined loads on different models. The out-of-plane displacement fields are captured and decomposed with buckling modes. The modal amplitude-axial load curves of different models are obtained, and the deformation process of stiffened panels is quantified. The deformation behaviors and collapse modes of stiffened panels in different load cases are then analyzed in combination with cloud diagrams.

The results show that the lateral load in combined load cases causes the yielding of the stiffeners at the endings before the ultimate state, resulting in the increase of the overall buckling mode's amplitude. As the lateral load increases, the overall buckling of the stiffened panels becomes the dominant collapse mode under combined load cases.

The findings of this study reveal the relationship between local and global buckling mode amplitudes and collapse modes during the deformation process of stiffened panels, and can provide useful references for the design of ship frame structures.