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To improve the bearing capacity of offshore wind turbine foundation, a pile-bucket composite foundation with bucket foundation and steel piles was designed. Based on the limit equilibrium method, the theoretical formula of horizontal bearing capacity of pile-bucket composite foundation was proposed with considering different pile numbers. The finite element analysis model was established to analyze the bearing capacity of pile-bucket composite foundation with different pile numbers, pile diameters and arrangements. The results show that the ultimate bearing capacity of pile-bucket composite foundation can be effectively improved for the same steel amounts of foundation. Compared with single bucket foundation, the bearing capacity of bucket foundation with 1 pile is increased by 44.27%, and the bearing capacity of bucket foundation with 3 piles is increased by 35.76%, while the bearing capacity of bucket foundation with 4 piles is increased by 34.73%. Obvious wedge-shaped equilibrium plastic strain is appeared in the soil foundation of the passive area. The more obvious the equilibrium plastic strain is, the higher the load sharing ratio of foundation soil is, and the higher the bearing capacity of foundation is. The high stress area of foundation is mainly concentrated in the top cover of foundation. [ABSTRACT FROM AUTHOR]

To investigate the reinforcement measures of solar greenhouse structure under extreme wind and snow disasters, the single frame model of solar greenhouse was established by ANSYS finite element analysis software with consideration of material nonlinearity, large geometric deformation and structural nonlinearity conditions. The whole processes of instability and failure for the solar greenhouse structure under four load conditions of wind, snow, wind-led blizzard and snow-led blizzard were respectively simulated. According to the instability mode and load-displacement relationship curve of the structure, the temporary reinforcement methods were proposed. The results show that the wind and snow resistance of the solar greenhouse is significantly improved after temporary reinforcement. The wind load bearing capacity is increased by 154%-300%,and the snow load bearing capacity is increased by 11%-129%. The wind-led blizzard bearing capacity is increased by 245%-273%, and the snow-led blizzard bearing capacity is increased by 203%-264%. [ABSTRACT FROM AUTHOR]

A new type of circular concrete-filled slotted steel tubular structure was proposed. Monotonic axial compression tests were carried out on six concrete-filled slotted steel tubular columns and six common concrete-filled steel tubular columns. The test results show that the slots can reduce the folding and buckling phenomena when the thickness of steel tube is small. The failure modes of concrete-filled steel tubular columns and concrete-filled slotted steel tubular columns are showed with remarkable dilation in mid-height when the thickness of steel tube is large. The slots of the steel tube have significant effect on the bearing capacity of smaller thickness of steel tube, and the bearing capacity of the concrete-filled slotted steel tubular columns is approximately 1.1 to 1.3 times of that of the common concrete-filled steel tubular columns. With the increasing of steel tube thickness, the ultimate load ratios of concrete-filled slotted steel tubular columns and common concrete-filled steel tubular columns are gradually decreased. The slots provide a local structure for the centralized release of deformation of concrete filled steel tubular columns under axial compression, which can avoid the longitudinal buckling of the steel tube effectively. Considering the influence of confinement efficiency of steel tube, the unified method for calculating the bearing capacity of circular concrete-filled steel tubular under axial compression with different structures is proposed, and the predicted results are more conservative than the experimental values. [ABSTRACT FROM AUTHOR]