Behaviour Analysis Of Novel Precast Corbel Joint Used In Self-lifting Prefabricated Wind Turbine Tower Under Vertical And Horizontal Loading

Recent development in technology and need for greater energy production has pushed the turbine manufacturers to begin installing taller wind turbine towers.At present majority of the utility scale turbines use steel towers and as the tower height increases along with it the diameter of the steel section also increases making them reach a limit where they are no longer feasible for transporting in the highways due to width and underpass limitations.Alternative to this can be the use of precast concrete segments and hybrid towers but this alone cannot address the logistics limitations connected with tower erections and installation such as;need of taller installation cranes and bigger vessels(offshore).Apart from all these conventional technologies for installation and erection of wind turbine towers,an innovative approach of a self-lifting tower system has been proposed.This will allow for a crane-less lifting of the tower.The proposed wind turbine tower is telescopic in nature which uses a self-lifting mechanism for a crane-less erection of towers.One of the most important structural components in the proposed tower are the novel corbel joint,they serve two important purpose;lifting and fixing/ securing tower segments.A finite element analysis was performed in Abaqus on the behaviour of novel precast corbel joint under the vertical and horizontal load.The FE analysis was performed in a quasi-static environment varying the loading rate and mass scaling.Three finite element models were developed to analyse the failure patterns and the performance of vertical and horizontal high strength bolted connections.The results indicated that the stiffness of the joint is greatly influenced by the horizontal connection provided at the flange of lower corbel,initial damage at this region significantly reduced the stiffness and later compression strut failure in the upper corbel region governed the ultimate capacity of the joint assembly.After performing the FE analysis of the joint and analysing the behaviour of the novel joint,it was crucial to provide with a suitable design method to calculate the strength of the joint.As for the complexity of the joint,it was regarded as a D-region and Strut-and-tie model was proposed for the joint design,the STM models were based on ACI 318-19.The joint capacity and failure patterns obtained from STM were compared with the results form FE analysis.Results indicated that the STM provided a safer estimate of the load carrying capacity of the joint except for one model,however failure patterns predicted were similar to what was obtained from the FE analysis.It was further concluded that,theoretical load capacity predicted by the STM provides a safer estimation of the load carrying capacity of the proposed novel precast corbel joint.This research provides a reference for the design of prefabricated corbel of the novel column-web splicing tower with self-lifting characteristics,and provides a method basis for the verification using a STM model of the prefabricated corbel joint.