COMPLEX MODAL-ANALYSIS OF A CONTINUOUS MODEL WITH RADIATION DAMPING

With reference to a simplified model for soil-structure interaction pr oblems, this paper describes the use of the complex mode superposition method for the analysis of the dynamical response of continuous syste ms. Analytical expressions are derived for complex frequencies and mod es of vibration. Two sets of orthogonality conditions are established for the model and used in decoupling the equations of motion. Numerica l applications showing the convergence of the method and allowing for the comparison with other methods of analysis are presented. Finally a physical interpretation for the complex modes of vibration is provide d and the source of radiation damping is clearly expounded. (C) 1996 A cademic Press Limited