Abstract: This paper presents an iterative combined approximation(ICA) approach for structural static reanalysis of all types of topologicalmodifications. The proposed procedure is basically an approximate two-stepmethod. First, the newly added degrees of freedom (DOFs) are assumed to belinked to the original DOFs of the modified structure by means of the Guyanreduction so as to obtain the condensed equation. Second, the displacementsof the original DOFs of the modified structure are solved using the ICAapproach. And the displacements of the newly added DOFs resulting fromtopological modification can be recovered. In order to illustrate theapplication of the present method, the layout optimal design of stiffenersin the plate-shell structure is given. In the layout optimization, thestrain energy sensitivity of the element and the rejection ratio areintroduced. In each iteration, a number of elements may be deleted. To savecomputational effort, the ICA is used to perform the reanalysis to updatethe modified displacements of the structure. The results show that the ICAmethod is effective for structural static reanalysis of the topologicalmodifications even though the large topological modifications are made, andit is easy to implement on a computer.