Comparison of several eigenvalue reanalysis methods for modified structures

Several eigenvalue reanalysis methods for modified structures are compared in terms of their computational accuracy and efficiency. These include the basic perturbation method, improved perturbation methods such as the William B. Bickford method and the method presented by Chen et al. (1994), the Pade approximate method, and Kirsch's combined method extended by Chen and Yang. All the above methods are used to calculate the approximate eigenvalues of a plane frame with 202 nodes and 357 beam elements. The results show that the methods can give satisfactory solutions if the changes of structural parameters are small, but the Pade approximate method and the extended Kirsch combined method are the most efficient among the five approximate methods for the case of large modifications of the structural parameters.