Research For The Mechanics Behavior Of Frame-core Structure With Strengthened Story

The frame - core structure has an extensive application in high-rise buildings. The external frame in the frame-core structure is the average frame, which can be made a number of choices in architectural innovation. In practical engineer, outriggers with large stiffness are adopted to avoid the effects of small lateral stiffness in the frame - core structure. Thus, the frame - core structure with strengthened story is formed.In the literature, the research on the frame - core structure with strengthened story focused on either the personal case or the comparison of simplified mechanical model by ignoring the action of certain components. However, the previous study is not full-scale and accurate on the mechanical capacity of the stuctural system, which will encourter the difficulty on aspects of choice structural system as well as determination and modification of structural scheme in sturctural design. Considering the effects of core, outriggers, floor beam and perimeter frame, a new sturctural computing model is established base on linear, small deformation and gemetrical parameters of structural components being continuons and constant over the vertical direction. A comprehensive analysis is done for the frame -core structure with strengthened story in the thesis.The primary work in the thesis is as following:First of all, in accordance with the characteristic of the frame - core structure with strengthened story, adding the outriggers and floor beams into the computing diagram of continuity analysis for frame-shear wall sturcture, the structural computing model is formed with the outrigger at the top in the frame-core sturcture. The formulas of the lateral displacement for the top outrigger braced frame - core structure are derived base on the principle of minimum potential energy, functional variation method and continuum approach for tall structures. According to the introduction of relative coordinates, frame stiffness characteristic parameter and stiffness characteristic parameter of outriggers, terse format analytic expressions for structure lateral displacement and internal force calculation under lateral distributed load, top concentrated load and top moment are obtained. With the retrogressed verification for the lateral displacement computing method and the comparison with finite element method, the results indicate the reliability of the method.Secondly, the influence of the frame stiffness characteristic parameter and stiffness characteristic parameter of outriggers on the structure lateral deflection and core moment under lateral distributed load, top concentrated load and top moment are analyzed. According to analyzing the effects of geometrical parameters of structural components on the characteristic value of stiffness, the impacts of the structural components on structure lateral deflection and core moment are obtained.Thirdly, the research focuses on the applicable range for frame-core structure with strengthened story, the optimal location and rigidity of outriggers. In particular, for the optimal location of strengthened story, the relationship between single and two strengthened story position and the core moment reversal is analyzed.Fourthly, the results show that the key factors for the impact of core shear force reversal are outriggers' moment, that is the reversal amount of core moment at the location of strengthened story, and outriggers' section depth. The method to reduce the internal force reversal are given. The design conception to adapt small sectional area and large section depth with outriggers is which can reduce the reversal amount of internal force and structural weakness story for analogous structure.Finally, the belt is analyzed. The results show that setting belt after setting outriggers can effectively reduce uneven degree of axial forces of the external frame columns. It can also dramatically reduce internal forces of outriggers and belt, improve the stress and strain states of the floor of the strengthened story, and increase the integrity of whole strengthened story.To sum, this thesis indicates that the key factors to effect the mechanical property of the frame-core structure with strengthened story are the frame stiffness characteristic parameter, the stiffness characteristic parameter of outriggers and the location of strengthened story. The relatiship among them determines the mechanical property of the frame-core structure with strengthened story. When belt and outrigger are set at the same story, the belt can improve the stiffness of the strengthened story and ensure the integrity of the structural.