A new eigensolution of structures via dynamic condensation

Dynamic condensation (or model reduction) is a commonly used algorithm to fast estimate some low eigenvalues and corresponding eigenvectors of structures by reducing the order of the original structural model to a smaller one. This paper proposes a new eigensolution technique via iterated dynamic condensation. The technique retains all the inertia terms associated with the removed degrees of freedom in an iterated form, which generates the reduced mass matrix similar to that obtained in the Guyan reduction method with a frequency-dependent perturbed term. The corresponding eigenvalues and eigenvectors of interest are obtained as those of the Guyan reduction method with perturbations by using an eigensensitivity-based iterative method. The effectiveness and accuracy of the proposed technique are numerically verified by using a steel frame and the GARTEUR structure.