An approximate analysis of combined system of framed tube, shear core and belt truss in high‐rise buildings

In this paper a mathematical model for the combined system of framed tube, shear core and belt truss is developed with the objective of determining the optimum location of belt truss along the height of the building. The effect of belt truss and shear core on a framed tube is considered as a concentrated moment at the belt truss location. This concentrated moment acts in a direction opposite to rotation due to lateral loads. The axial deformation functions for web and flange of the frames are considered to be quadratic and cubic functions, respectively; developing their stress relations and minimizing the total potential energy of the structure with respect to the lateral deflection (u), rotation of the plane section (ϕ) and unknown coefficients of shear lag (α1, α2, β1 and β2), the mathematical model is developed. This model yields the displacement, axial stress distribution and bending stiffness as a function of the height of the combined system. The range application and validity of the proposed model is demonstrated by several numerical examples (30-, 40- and 50-storey buildings). The effects of belt truss position on lateral displacement and stress distribution are investigated and the optimum location for belt truss is obtained. Copyright © 2009 John Wiley & Sons, Ltd.