Frequency analysis of buildings
A simple procedure with design tables was made available for asymmetrical buildings developing predominantly bending deformation. The equivalent column for the lateral vibration analysis was created by simply adding up the effective shear stiffnesses and the local bending stiffnesses, respectively, of the individual bracing units. The model which is used for the pure torsional vibration analysis of the building is an equivalent cantilever of thin-walled, open cross-section which has effective Saint-Venant stiffness and warping stiffness. A multi-storey building may develop lateral vibrations in the several principal directions and torsional vibration around its vertical shear centre axis. A great number of methods have been developed for the dynamic analysis of individual frames, coupled shear walls and shear walls. The shear stiffness of the system originates from the shear stiffnesses of the frames and coupled shear walls. The equivalent column is situated in the shear centre of the bracing system and torsional vibration develops around the shear centre.