Inhomogeneous beam-like models for the dynamic analysis of multistorey buildings

The present paper proposes a simplified inhomogeneous beam-like model, suitable for the dynamic analysis of buildings with non-uniform vertical distribution of mass and stiffness. Asymmetric distribution of stiffness within the floors, which leads to torsional effects, can be also taken into account. The equations of motion of the proposed spatial asymmetric beam-like model are derived through the application of Hamilton's principle. The linear dynamic behaviour of the inhomogeneous beam-like element is then evaluated by discretizing the continuous model according to a Rayleigh-Ritz approach based on a suitable number of modal shapes of uniform shear torsional beam. The comparison of the results with those obtained by means of three-dimensional FEM models shows the efficacy of the proposed approach.