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Title: Analysis of framed-tube structures for high-rise buildings
Author: Bose, B.
ISNI:       0000 0001 3471 2397
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 1976
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All the previous works on Framed-tube structures required the services of a digital computer of reasonable size to obtain a solution. There appears to be a distinct need to develop a simple method which will enable hand-calculations to be carried out rapidly in the early stage of design to give a reasonable, assessment of the structural behaviour and to make preliminary estimates of the main structural element sizes. In the simple approximate analysis presented in this thesis, the rigidly-jointed perimeter frame panels are replaced by equivalent orthotropic plates, whose properties are chosen to represent both the axial and shearing deformation characteristics of the frames. The use of an artificially low shear modulus G enables the racking deformations of the frame to be simulated. The stress distributions in the panels are assumed to be represented with sufficient accuracy by polynomial series in the horizontal coordinates, the coefficients of the series being functions of the height coordinate only. After satisfying the equations of equilibrium, the unknown functions are determined from the principle of least work by means of the calculus of variations. Two methods of analysis are suggested. In the first very simple method the stress distributions represented by the basic beam theory are modified to include the effects of shear lag. Closed form solutions are presented for three standard load cases, a uniformly and a triangularly distributed load, and a point load at the top. Design curves are developed to enable solutions to be obtained rapidly. A limited study is carried out to examine the effects of variable corner column stiffness and the ratio of column width to spandrel beam depth on the optimisation of the Framed-tube structure. A more general analysis of the Framed-tube structure yields simultaneous differential equations for the two unknown functions which are solved for the three standard load cases. The effects of an elastic base on the boundary conditions of the Framed-tube structure are considered. Framed-tube structures with different stiffness regions are also examined. An analogous simplified method is presented for the analysis of Framed-tube structure subjected to torsion. Closed form solutions, and associated design curves, are presented for the three standard load cases. The behaviour of Bundled-tube structures is more complex and a number of simplifying assumptions are made to reduce the number of unknown functions to a manageable size. Both simple and more general methods are presented for the analyses of such structures with two and nine modular tubes. A method is presented to consider the likely effects of the flexibility of the spandrel beams on the stress distribution in a Framed-tube structure subjected to vertical forces. A number of numerical examples are given which illustrate the various aspects of the theories developed and enable the best disposition of the materials to be made. The results from a series of tests carried out on Perspex models are compared with the theoretical values in order to assess the validity of the approximations.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral