A method for the dynamic re-analysis of nonlinear systems

Re-analysis techniques afford an efficient strategy determining either static or dynamic response of modified systems. Exploiting the results from a reference structure re-analysis techniques offer the approximate, and in some cases the exact, response of the modified structure reducing the computational effort involved in a fresh analysis. The sustained progress in the framework of Computational Mechanics quite recently has been focused in coping with the re-analysis of nonlinear dynamic response of modified systems. The few contributions devoted to this subject are aimed to improve the efficiency of integration algorithms. In this paper a new approach has been proposed for the re-analysis of nonlinear hysteretic systems. The method allows determining the nonlinear dynamic response of a modified system by the knowledge of results from a reference structure. Specifically, the equation governing the variation of the modified response with respect the original one is first derived. Therefore, the pertinent step-by-step integration scheme is determined exploiting only quantities already determined by solving the reference structure.