With An Enhanced Layer Of High-level Framework - The Structure Of The Core Tube To Enhance The Layer Location And The Structural Stiffness Optimization

On the basis of systematical analysis for the frame-core tube structure with outriggers (FCTSO) subjected to equivalent static loading, the regularity of the structure characteristics is investigated. It is shown by the analysis that the important parameters, having influences to the inner forces and deformations of FCTSO, are: (1) the stiffness of the core, outriggers and perimeter frame columns, (2) the location and magnitude of the outriggers, (3) the cross-section variation of the core, outriggers and perimeter frame columns, (4) and the kind of the equivalent static loading. The structural stiffness characteristic parameter A, which is the key parameter of the structure, is adopted to illustrate the influence of the stiffness of the core, outriggers and perimeter frame columns. The relationship between the reductions of the top drift and core base moment and A is studied, and the range of /I corresponding to the rational efficiency of the structural components is proposed.The Simplex Method is used to determine the optimal locations of the outriggers, which are separately obtained with respect to the objective function: minimizing the top drift, minimizing the core base moment, and maximizing the first natural frequency of vibration. The functions of the optimal heights of the outriggers and /I are fitted by using the Least Squares Method. The optimal heights of the outriggers corresponding to these different objective functions are compared and analyzed. This leads to some useful conclusions for the structural design.The Complex Method is used to determine the optimal stiffness of the core, outriggers and perimeter frame columns, whose objective function is minimizing the core base shear force caused by the earthquake. A lot of calculations and analyses for the FCTSO are carried out by microcomputer for a series of different engineering parameters, so as to get the design charts of the optimal stiffness ratio of core versus outrigger, corresponding to the stiffness ratio of core versus perimeter frame columns, which are valuable for engineering use.Based upon the Transfer Matrix Method for the structure with multi-outrigger and varied cross-sections of the core, outriggers and perimeter frame columns, the equations used to calculate the lateral deformations and the internal forces, the natural frequencies and the vibration mode shapes are derived. Comparing with the traditional analysis method, this method not only can be conveniently implemented by microcomputer, but also can be conveniently used by the Mode Superposition-Response Spectrum Method to analyze the structural earthquake effect. For the purpose of optimization by using this method, the first four vibration modes are considered to calculate the earthquake effect.According to the above-mentioned optimum theory and analysis method, four programs: OPTM-H (outrigger location optimization), OPTM-K (structural stiffness optimization), TMSA (structural analysis by using Transfer Matrix Method), and TMEA (earthquake response analysis of structure by using Transfer Matrix Method) are rplied. The typical engineering example analysis shows the satisfactory results of the proposed method. On the basis of the present research, some conclusions are drawn as important references for the seismic design of FCTSO. The proposed methods and the compiled programs are of practical values for engineering use.