Abstract: This study presents three static reanalysis methods forlarge-scale structures with large modifications of structural parametersbased on the Combined Approximation (CA) method. For large-scale structureswith large changes in the design, the Combined Approximation method can notprovide enough accurate results. To improve the accuracy of the results inreanalysis of the modified structure, three CA-based static reanalysismethods are presented by introducing several strategies, such asdisplacement iterative correction and stiffness progressive approximation.Two numerical examples are presented to demonstrate the validity and theimprovement of the proposed methods, and the results show that the methodsgiven can provide accurate approximations and can significantly reduce thecomputational effort involved in reanalysis of large-scale structures withlarge modifications. Comparisons of the computational costs of these threepresented methods are made.