Displacement and natural frequencies of tall building structures by finite story method

An approximate approach, termed finite story method (FSM), is proposed for the analysis of tall building structures under lateral loads. The method is based on nodal displacement fields obtained from two-story substructures and intended to approximate shear, bending and torsion components of global deformations. Because floor slabs are considered in-plane rigid, these deformations are described by translational and rotational displacements of the slabs. Thus, nodal displacements are obtained by interpolating the floor slab displacements, where the interpolation coefficients come from the nodal displacement fields. The latter represent deformation patterns corresponding to unit relative floor slab displacements of the two-story substructures. By introducing this interpolation, the overall structural analysis is simplified to only five principal unknowns per floor. The efficiency and accuracy of the method are demonstrated for static and dynamic examples by comparing the results with standard three-dimensional finite element analysis.