Updating undamped structural models using displacement output feedback

A novel numerical method for updating stiffness matrix by displacement output feedback technique is presented. The required displacement output feedback gain matrix is determined by the QR-decompositions and the singular value decompositions of matrices, and thus the optimal approximation stiffness matrix is found and the large number of unmeasured and unknown eigeninformation of the original model is preserved. The proposed method is computationally efficient since it does not require iterations and the updated stiffness matrix is also symmetric and has the compact expression.