Vertical vibrations of base isolated machine foundations

Abstract EN

Vibration of base isolated machine foundations has been studied using the Scaled Boundary Finite Element Method (SBFEM) and the cone model method.

The dynamic stiffness of soil supporting rigid mass less foundation was determined.

This stiffness is of complex value.

The real part represents the reflected energy of the restoring and inertial forces while the imaginary part represents the energy dissipated within the endless extent of the soil as a geometric damping.

The effect of geometric and material properties of soil upon the real and imaginary parts of the dynamic stiffness was determined and represented in terms of dimensionless charts for the frequency range of interest.

Results have shown that increasing the embedment ratio has a significant effect on the dynamic stiffness, it increases the dynamic stiffness considerably.

The effect of stiffness ratio (stiffness of isolator / stiffness of soil) was demonstrated for isolated machine foundations.

The use of soft isolators reduces the dynamic response of foundation and the soil reaction.