Mode coupling in the torsional—flexural buckling of regular multistorey buildings

Abstract

AbstractAn analogy is established between the mode coupling of columns under concentrated end forces and those subjected to uniformly distributed axial forces. It is demonstrated that the cubic equation derived for the mode coupling of columns under end forces can be used directly for the more practical case of cantilevers under uniformly distributed axial load. Simple closed‐form formulae and design tables are given for the torsional—flexural buckling of cantilevers. These formulae can be used directly for the spatial stability analysis of core supported regular multistorey buildings. A numerical example is provided to show the step‐by‐step procedure to be followed in practical structural design for stability. The results of a series of tests on small‐scale multistorey building models are presented. The loadbearing system of the models consists of columns, shear walls and support cores. The results indicate that the contribution of the columns to the lateral and warping stiffness of the support system may be of considerable magnitude. The more sensitive the structure is to torsion, the greater the effect of the columns.