Research On The Design Theory Of Support Columns In The Super High-rise Multi-columnframe-core Tube Structure Constructed By The Top-down Technique

The top-down construction method is a special but efficient construction technique,the corresponding structural design techniques are extremely special.The structure system and the support column are the the core points.Based on the top-down technique on the super high-rise buildings,this paper describes the details of the multi-column frame-core tube structure,the concrete-filled steel tubular(CFST)with headed stud shear connectors or longitudinal stiffeners.More details is as follows:(1)Based on the tube-in-tube structure and the frame-core tube structure,this paper presents the multi-column frame-core tube structure for the super high-rise building.It is especially applicable for the super high-rise buildings constructed by the top-down technique.Elastic analysis under frequent seismic actions have been carried out on nearly 30 super high-rise buildings.The influence from the column spacing,height and aspect ratio on the structure system have been researched.And the suitable column spacing,height and aspect ratio have been described in this paper.(2)Presents the design method of the headed stud shear connectors in the CFST columns.To study the actual mechanical behavior of the headed stud shear connectors welded to the interface between concrete and steel of the CFST columns and the concrete-steel bond strength in the CFST columns without headed studs,push-out tests have been carried out on 25 full-scale square and circular CFST columns.The experimental and analytical works in this paper provide the failure mechanism and the design method of the headed stud shear connectors in the CFST columns.(3)Presents the design method of the CFST with longitudinal stiffeners.To study the actual mechanical behavior of the CFST with longitudinal stiffeners,axial compression tests have been carried out on 12 square CFST columns.The failure mechanism and the design method of the CFST with longitudinal stiffeners for the structural engineersare also presented in this paper.