Centre of Rigidity Concept and its Application to the Static and Dynamic Analysis of Multi-Story Buildings

Abstract

<p>The object of this investigation is to establish a method of determining the locus of centres of rigidity of an asymmetric multi-story building structure, which can be applied to determine, with acceptable accuracy, the shear forces in the load-resisting panels in a static or dynamic analysis.</p> <p>Based on a more general definition for the centre of rigidity within a particular story of a multi-story building structure, a method is developed for the evaluation of the locus of centres of rigidity of a multi-story building structure. Other existing methods are also discussed. It has been found that the locus of centres of rigidity is not only a function of the structural properties but also a function of the distribution of lateral forces acting on the multi-story building structure. It has also been shown that for a building structure consisting of panels which are disproportional in stiffness, the traditional method (in which only the structural elements in an isolated story is considered for the determination of the centre of rigidity within that story) do not give a satisfactory estimation of the locus of centres of rigidity.</p> <p>The applicability of the locus of centres of rigidity to the evaluation of the shear forces in the load-resisting panels in a static, analysis is investigated. Based on the results of this investigation, methods of determining the panel shear forces in a static analysis are recommended for various types of building structures.</p> <p>The applicability of the locus of centres of rigidity to the evaluation of the panel shear forces in a dynamic analysis using a three degree-of-freedom model is also studied. The results of this study show that the distribution of the panel shear forces in a frame building structure obtained by using the model, agrees well with that obtained by using a three-dimensional dynamic frame program. The model can only provide a rough estimation of the magnitude of the panel shear forces.</p>