Study On Mechanical Performance Of Lattice Concrete-filled Steel Tubular Wind Turbine Tower Joints

With the increase of the single unit installed capacity of wind turbine,higher requirements have been put forward for the height and reliability of wind power tower.a concrete-filled steel tubular lattice wind power tower with better reliability,convenient transportation,assembly and economy has emerged.As the key parts of new type of wind turbine tower,the joints have very complex stress state,and once they failed,the transmission path of the inner forces for the tower structure will be changed or broken,which will cause the collapse of whole wind turbine.At present,the research on lattice wind power tower joints of concrete-filled steel tube focuses on welded tubular joints and Joint with gusset plate.However,the above two types of joints are studied separately,and no specific and targeted comparative analysis has been carried out.Which type of joints is more suitable for the construction and promotion of wind power tower.Based on this,for the same tower structure,the concrete filled steel tubular model tower with intersecting joints and tubesheet joints is adopted.The monotonic static horizontal load test and low cyclic repeated horizontal load test are carried out.The finite element software ABAQUS is used to simulate and expand the parameters.and the main contents and results are as follows:(1)Under the monotonic static horizontal load,the typical failure characteristics of the model tower are the failure of the joint zone;under the low-cycle repeated horizontal load,the typical failure characteristics of the model tower are the radial direction of the base material of the intersecting oblique web joint.The tear is combined with the breakage of the column foot column.The test results show that the model tower with intersecting joints has better seismic performance and higher bearing capacity than the model tower with tubesheet joints,which is more beneficial to the construction and popularization of concrete-filled steel tube wind turbine tower.(2)Under the monotonic static horizontal load,the compression ratio of the web of the middle layer of the model tower is 1.2,and the ratio of the tension of the bottom layer node is 1.17.Under the Low cycle repeated horizontal load,the tension ratio of the web of each layer is 1.15~1.23.Under different loading modes,the stress variation trend of model tower is similar,and its stress distribution is bottom layer > middle layer > top layer.(3)The finite element numerical simulation of the experimental model was carried out.The parameters of the concrete-filled concrete-structured plane tower were analyzed by the ratio of the ratio of the diameter of the web to the column and the wall thickness ratio.The results show that with the increase of the thickness ratio and tube diameter ratio of Web rod to column,the failure mode of the tower develops from the web rod failure at the joints of each layer to the joint failure of Web rod and column foot.When the ratio of the diameter of the web to the tower is increased from 0.3 to 0.48,the ultimate bearing capacity of the model tower connected by the joint is increased by 67.8%,and the ultimate bearing capacity of the model tower connected by the tube-plate joint is increased by 66.8%.As the wallthickness ratio of the web to the tower increases from 0.5 to 1.75,the ultimate bearing capacity of the model tower connected by the joints is increased by 136%,and the ultimate bearing capacity of the model tower connected by the tube-plate joints is increased by 131%.