| The development of onshore wind resources has turned to the low speed wind areas in recent years.Therefore,the technology of tall wind turbine towers has become a research hotspot.As a traditional tower structure,the thin-walled steel tube tower is generally characterized by the local buckling behavior and imperfection sensitivity.In order to overcome these shortcomings,a new type of stiffened steel tube tower was proposed,which could improve the bearing capacity and stability of the wind turbine tower.The bearing capacity of stiffened cylindrical steel tube of wind turbine were studied comprehensively by experimental,theoretical analysis and numerical simulation methods under compression-bending-torsion loads.The main contents of this study are as follows:(1)Four unstiffened steel tube tower specimens and eight stiffened steel tube tower specimens under combined compression-bending loads and combined compressionbending-torsion loads were tested respectively.The failure modes and normalized loaddisplacement curves of specimens were obtained.The influence of stiffener on force mechanism,ductility,and bearing capacity were carried out.(2)Finite element models of unstiffened steel tube tower specimens and stiffened steel tube tower specimens under axial compression,compression-bending and compression-bending-torsion loads were built through ABAQUS.The modeling process was specified,including element selection,constitutive relations of materials,boundary conditions,initial defects and mesh generation.The accuracy and reliability of finite element models were verified by the similarity of bearing capacity and failure modes between the results of tests and finite element models.(3)Based on the simulation results of finite element model,the influence of parameters,such as yield strength of steel,the form of stiffeners,the dimensions of stiffeners,the number of stiffeners,the ratio of section diameter to thickness,and the initial imperfection,were carried out.What’s more,some suggestions for the stiffeners design were given.(4)Based on theoretical analysis and parameter fitting,the calculation method for compression bearing capacity was proposed.Moreover,the correlation expression between compression and bending capacity,and the correlation expression between bending and torsion capacity of stiffened steel tube tower under combined loads were obtained respectively.The correlation expression were accurate and simple. |
