09-10-2014, 03:35 PM
In this study analytical method for modelling the dynamics of buildings with flexible floor diaphragms is developed. The method has been applied to a) long narrow rectangular multistorey buildings with a number of transverse frames (or walls), and b) horizontal setback buildings with arbitrary plan shape. The floors are braced as beams with flexural deformations only or with flexural and shear deformations while including the effects of in-plane floor flexibility. The vertical elements (frames or walls) are treated as frames or beams. The mass is lumped at floor-frame intersections. The eigenvalue problem of the building is expressed with the aid of direct procedure. For these types of buildings, the most general conditions which make a building separable have been derived. A "separable" building is one for which the natural frequencies and mode shapes can be obtained from the natural frequency and mode shapes of a typical floor and a typical frame of the building. The separable building is shown to have two types of modes a) those in which in-plane floor deformation d