Floating foundations play a vital role in exploring offshore energy. After analyzing various floating foundation concepts, this paper presents a novel buoyancy-distributed floating foundation (BDFF) inspired by the decentralized concept. The calculations of a floating system based on the BDFF design were performed for a series of wave conditions. The potential theory and the boundary element method (BEM) were used in the numerical progress. A broader view was focused on the impacts of wave frequency and wave directions on the system. The proposed floating system was further validated through wave tests in a wave tank, showing that the potential theory can satisfactorily predict the RAOs in regular waves. Moreover, numerical results and experimental results were compared with a conventional SPAR. Finally, the coupling relationship between six degrees of freedom was described.

The space grid structure is widely used in large-span and large-scale buildings due to its excellent stiffness and lightweight. However, the joint connection is complicated since many struts emanate from one joint. In this paper, we proposed a novel joint connection with five struts and a space grid structure called the bi-hexagon grid structure (BHGS). The mechanical behavior of the proposed grids was investigated by comparing different double-layer and multi-layer grids by virtue of the Ansys parameter design language. The results show that the proposed structure can significantly reduce material consumption and improve installation efficiency. The comparison results also show the BHGS has a good stress distribution under uniform surface loads. However, the deformation is slightly large, which is acceptable considering the practical application. A configuration method and mechanical behaviors of a double-layer dome based on the bi-hexagon grid structure were presented as a particular application as well as the structural optimization. In addition, an assembly strategy was further given to realize the modular design.

The comprehensive utilization of offshore renewable energies is an effective way to solve the intermittency and variability of power supply. This paper aims to present a hybrid floating system (HFS) based on a modular buoyancy-distributed floating foundation (BDFF) that can be equipped with a horizontal-axis wind turbine, solar panels, and wave energy converters (WEC). A simplified test model with a Froude scale ratio of 1/10 is employed to perform the experiments in a deep-water basin to validate the numerical results computed from the code program ANSYS AQWA based on the potential flow theory. The Response Amplitude Operators (RAOs) under regular waves are compared to evaluate the hydrodynamic performance. There is a good agreement in the surge, pitch, and heave RAOs for experiments and the numerical simulation, with a maximum of 6.45 degrees per meter for the pitch motion. Furthermore, the mooring tensions in the time domain are analyzed under different wave conditions.The tension RAOs from simulations are slightly higher than those from measurements with a maximum value at the period of 3.416 s. The mooring line on the windward side has a more considerable mooring tension that is far less than the allowable tensile strength, especially under the wave height of 2 m and the wave period of 2.873 s. The influence of loaded weight representing solar panels is weak, and the impact of winds is acceptable, as the platform deviates 1.3 degrees from the equilibrium state under the test wind speed. Eventually, the effect of irregular waves on the HFS is presented with the critical parameters of mooring tension and pitch motion. The results show that the HFS has a good motion performance.

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