A hybrid computer system has been used to simulate some five-storey structures excited by ground motion. Five types of buildings were investigated to find the effect of some structural parameters on the dynamic response of the buildings. The factors that have been considered are the distribution of stiffness and mass in the structure, the type of foundation condition, and the action of viscous damping.
The results indicate that it may be reasonable to calculate the base shear forces, created by ground motion, as a function of the fundamental period of the building. In the case of lightly damped structures, however, the distribution of forces through the height of the structure is also shown to be dependent on the other dynamic characteristics of the building, as well as the frequency content of the ground motion.
Viscous damping considerably reduces the forces acting on a structure, and also tends to eliminate modes of vibration other than the fundamental. A pinned-end foundation condition is also shown to reduce the forces acting on the lower storeys of a building compared with the fixed-end condition.