The Basic Study Of Mechanical Properties On Diagrid Tube Structural System For High-rise Buildings

The Diagrid Tube Structural System is an innovative structural system for high-risebuildings, which is developed from Braced Tube Structure. Generally, Diagrid TubeStructure utilizes diagonals, instead of the traditional vertical columns, to form anexterior tube. Compared with conventional tubular systems, Diagrid Tube StructuralSystem provides significant lateral resistance, and represents an excellent developmentfor tall buildings. In recent years, Diagrid Tube Structures have seen a worldwideapplication as the major structural system for certain tall buildings. However DiagridTube Structural System is only applied in a limited quantity of building cases, thesystematic research on it is not yet implemented.Based on the practical experience and the few existed research on diagridstructures, the basic mechanical behavior of Diagrid Tube Structural System isinvestigated in this dissertation. The main work and achievements are as follows:1) The basic conception of Diagrid Tube Structural System is extracted and theconfiguration of diagonals is developed. A preliminary design guideline specifically fortwo types of Diagrid Tube Structure composed of diagonals with gradually changingangles is proposed.2) With respect to the geometric parameters of height-to-width aspect ratio,diagonal angle, number of bays, along with the structural elements of main beam, cornercolumn, connection pattern, the sensitivity investigation of the lateral stiffness ofDiagrid Tube Structure composed of diagonals with uniform angle is conducted. Theresults indicate that the lateral stiffness of Diagrid Tube Structure is much larger thanconventional tubular structures, and the maximum lateral stiffness is achieved withoptimal diagonal angle.3) A valid method for estimating the cross-section area of diagonals in preliminarydesign of Diagrid Tube Structure is deduced. By using the section estimating method,the sensitivities of lateral stiffness of Diagrid Tube Structure composed of diagonalswith gradually changing angles is investigated. The advantage of diagonals withchanging angles over diagonals with uniform angle is confirmed. The optimalcombinations of diagonal angles are presented.4) The study on diagonal internal forces of Diagrid Tube Structure is conducted. Diagonals with relatively small internal forces are observed. However, due to the spatialbehavior of diagrids, the shear lag effect of Diagrid Tube Structure is smaller thanconventional tubular structure. The shear lag ratio at1st story increasesas the diagonalangle increases.5) Ring beam internal forces of Diagrid Tube Structure are analyzed, whichindicates that the main beams and nearby floors around corner suffer larger tensileforces. Several measures are considered to improve this phenomenon.6) The elasto-plastic analysis is conducted to evaluate the seismic performance ofDiagrid Tube Structure. Large overstrength is confirmed for Diagrid Tube Structure,however, the structural ductility is not sufficient owing to the buckling of diagonals.Buckling-Restrained Diagonals and Concrete-Filled Steel Tubes are used to improve thestructural ductility.