This study investigates the dynamic motion and structural response characteristics of ships with large openings in the middle under wave conditions.

Referring to the characteristics of cargo loading and large openings in the middle of container ships, a stiffened plate ship model is designed and manufactured. A series of linear and nonlinear operating condition tests are then conducted in a wave-making tank to measure the elastoplastic deformation of the ship model under the combined action of ballast and waves, as well as stress changes in the deck area.

The results indicate that the appearance of structural plasticity slightly reduces the growth amplitude of the overall pitch motion and prolongs the occurrence time of sagging deformation; the larger the wave amplitude, the more significant the high-frequency vibration of the structure it causes.

For ships with large openings in the middle, the high-frequency stress generated during sagging is greater than that during hogging, and the superposition of low-frequency stress poses a greater threat to ship safety, which needs to be considered in ship design. The proposed ship model can provide valuable references for the study of the plastic collapse of ships in waves.