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This study investigated the structural response characteristics of a novel single-point mooring gravity-type deep-water (SPM-GDW) net cage under irregular waves and currents. A hydrodynamic numerical model of the cage was created and validated through model experiments. Based on the validated cage model, the structural response characteristics such as cage motion response, mooring line forces, and floating collar stress were studied, considering the actual operating conditions in the target sea area. The response time history curves, wave height time history, and spectral density statistics were studied and compared. The results showed that the heave motion of the cage was consistent with wave elevation in the vertical direction and mainly influenced by wave conditions. The surge motion of the cage was closely related to the current, with a significant lag effect compared to wave elevation motion. Low-frequency loads under the combined action of waves and currents had a significant impact on the surge motion of the cage. In addition, the mooring line tension and pontoon stress were closely related to the wave elevation, with peak values of tension and stress occurring almost simultaneously with the peak wave elevation. However, the pontoon stress exhibited high-frequency response characteristics while satisfying the wave frequency response trend. It was found that the flow velocity had a significant impact on the spectral density of mooring line tension and pontoon stress in the low-frequency range, with an increase in spectral density values as the flow velocity increased. The structural response characteristics identified in this study provide a computational basis for the optimized design and analysis of single-point mooring gravity-type deep-water cages. [ABSTRACT FROM AUTHOR]

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To study the problem of the dynamic responses of the damaged floating bridge, this paper establishes the numerical model of a nonlinearly connected floating bridge based on the Kane method. The accuracy of the numerical model is verified by comparing the results from relevant literature and the model test conducted. Subsequently, considering the damaged opening at the bottom of the pontoon, the impact of different vehicle speeds, opening sizes, as well as connection gaps between pontoons on the dynamic responses of the damaged floating bridge is studied. Some conclusions are obtained: The flooding brought by the damaged opening causes the rise in vertical displacements of the damaged pontoon and the forces on the connectors. The opening and closing of the longitudinal gaps affect the sinking speed of the damaged pontoon, and the size of the gap influences both the maximum sinking displacement and the vibration period of the floating bridge. The maximum vertical displacements of the damaged pontoon and the flow rate variation at the opening location increase as the opening size expands. Reasonable selection of vehicle speeds and connection gaps between pontoons can prevent excessive dynamic responses of the damaged floating bridge. [ABSTRACT FROM AUTHOR]