EVALUATION OF SOIL DYNAMIC IMPEDANCE IN SOIL-STRUCTURE INTERACTION ANALYSIS

An important part of the dynamic interaction analysis is the evaluation of the matrices related to impedance function which are essentially dependant on the frequency of excitation. To develop the matrices of dynamic impedance, the interaction forces have to be related to the stiffness and displacement matrices of the system. The complex stiffness matrix represents the dynamic stiffness and the damping characteristics of the foundation.Using Dynamic Infinite Elements (IFE), a new and rational approach is adopted here to evaluate the stiffness coefficients of the foundation truncated boundaries.. The total equivalent stiffness matrix of all fictitious generalized springs and the equivalent damping matrix of all fictitious generalized dashpots are evaluated at a specific frequency, say ωs . Analyses in frequency domain are conducted in which the infinite elements are replaced totally by the generalized spring and dashpots connecting the structure and foundation. Discussion on the advantages of the concept introduced here and the results obtained continues throughout the paper.