Study On The Performance Of Concrete-filled Steel Box Connection Of Prestressed Concrete-steel Hybrid Wind Turbine Tower

Wind energy is a kind of abundant, widely distributed, renewable resource. So far, the domestic wind turbine towers have mainly been built in steel form. With the development of wind turbine in the multi-megawatt category, the total height and the dimension of the cross section of the tower are increasing, so the manufacture and transportation of the tower become more difficult and expensive. The concrete tower can solve problems in production and transportation. Due to the large dead weight, the single concrete tower can not meet the demand of the increasing height of the tower. For the above reasons, the hybrid wind turbine tower by composing the concrete tower and the steel tower can make full use of the advantages of the two materials and provides a new way for the development of the higher wind turbine tower. The connection between the prestressed concrete and steel tower is critical when designing the hybrid wind turbine tower. In this thesis, a new type of concrete-filled steel box connection is proposed, which can enhance the overall stiffness of the connection, improve the mechanical behavior of the concrete below the steel box, make the stress distribution more uniform and avoid the appearance of the tensile stress in concrete. Currently, the available design and analysis on the connection of prestressed concrete-steel hybrid tower are very few. The numerical analysis and experimental study on the connection are carried out in this thesis, which can provide reference for the design and research on hybrid wind turbine tower in our country.The main works of this thesis are listed as follows:(1) The basic design concept on the connection of hybrid wind turbine tower is proposed. The proposed connection has great advantages by comparing with the other three methods. The computational analysis on its stress characteristics is carried out through the simplified mechanical model.(2) The whole models of the prestressed concrete-filled steel box connection and traditional thick flange connection are analysed by the finite element software ABAQUS. The elastic and elasto-plasticity analysis are carried out. It comes to the conclusion that the mechanical behaviors of concrete-filled steel box connection is excellent.(3) Taking a 2MW wind turbine tower as an example, a scale connection unit model is designed and tested under static load by the hydraulic actuator. The mechanical behaviors of the test models are summarized. Results show the rationality of the proposed connection design.(4) Based on the experimental study on the connection, finite element analysis is carried out on the scale test model, which verifies the accuracy of the test by comparing the experimental and numerical results.