Seismic Performance Of Dry-Connected Prestressed Precast Concrete Wind Turbine Tower (WTT) Structures

The precast concrete wind power turbine tower(WTT)structure is one of the development directions for the wind farm construction in the future.In recent years,it has received a lot of attention but few systematic researchers.The research object of this dissertation is to explore the dry-connected prestressed precast concrete WTT structure.The WTT structure is divided into several sections along the height direction,and each section is equally divided into eight pieces.Precast concrete pieces can be assembled as an entire structure on site.This new type of piece can be prefabricated by formwork in large in factories,and then transported to the site for assembly,which is very convenient for construction.But whether the mechanical properties of the dry-connected joints are good is the main concern of this issue.In this dissertation,a new type of dry-connected joint form named "concave and convex groove" for the precast concrete WTT structure is developed by setting a pin bolt steel bar to connect two adjacent cylinder pieces.To ensure the entire stress of concrete tower cylinder from bottom to top,a posttensioning external prestressing system is adopted.Therefore,this type of connection can obtain higher seismic performance of the structure with simpler construction technology and lower economic cost than normal concrete one.In view of this,based on previous research results,the seismic performance of dry-connected prestressed precast concrete WTT structure is analyzed in this dissertation through numerical simulation and theoretical research,establishing a set of seismic performance evaluation system.The main research contents and achievements can be found the following:Firstly,the failure mechanism and stress distribution law of the interface were studied by analyzing the finite element model of the dry-connected interface of the precast pieces.The validity of the interface finite element model without "convex groove" was performed by the data of the completed pull-out test.The finite element model of the interface with "convex groove" was constructed and the elastoplastic static analysis was performed to study the entire process of push force and slip displacement relation curve,failure mode and stress distribution law of the interface under different parameters,to clarify the basic mechanical properties of the interface.Secondly,a part of local WTT structure was selected as the research object to establish the finite element model,and the elastic-plastic analysis was carried out to study the mechanical properties of the part of local WTT structure and prove the good integrity of the tower by applying external prestressing reinforcement.Through the pushover analysis,the loaddisplacement relationship curve was obtained,the failure mechanism and failure mode were defined,and the influence law of axial compression ratio and the prestress level on the mechanical properties of the local WTT structure was determined.The pseudo-static analysis was carried out to obtain hysteretic curves and skeleton curves to study its seismic performance.Thirdly,taking the entire WTT structure as an object,a dynamic finite element model was constructed and the seismic response analysis method is put forward.The time-history analysis of seismic dynamic response under four peak accelerations under three seismic waves was carried out.The peak accelerations were adjusted to 0.1g,0.15 g,0.2g and 0.3g,respectively,and the time-history curves of displacement and acceleration at the top of the WTT structure were received,and the internal force response was also obtained.The results show that the horizontal displacements of the WTT structure were under the allowable limit of the standard displacement value under the peak accelerations of 0.1 g,0.15 g and 0.2 g,and the prefabricated parts of the WTT structure show a good cooperation ability.To sum up,the failure mechanism and basic mechanical properties of connection interfaces for the dry-connected WTT structure are clarified through the investigation by combining theoretical analysis and numerical calculation,and the results can be concluded that the dryconnected prestressed concrete WTT structure has good ductility and seismic performance.