Aseismic Dynamic Design of Multistory Systems

Investigation of a multimass model consisting of a cantilever with masses concentrated at floor levels and sections with varying moments of inertia between the floors, submitted at its base to a given ground-motion expressed by the time function f(t). For cases of actual buildings with shear walls, the shear deformation is also taken into account. The model is formed under the usual assumptions of masses lumped at floor levels, linear elastic material, no dumping, and uncoupled translations in two perpendicular directions. The shear-building assumption is dropped and the opposite assumption of no restraint by the floors on the rotation of vertical members, is made. A one-stage solution program is proposed, elaborated in matrix form, relying on extensive use of a proper analog and digital computers and leading to the determination of the maximal dynamic shear forces and bending moments produced in the vertical elements. A full numerical example of a nine-story hotel building with sinusoidal ground acceleration illustrates the method.