Structural health monitoring using parameter identification methods

A structural health monitoring method for determination of damages in structural system is developed using state variable model. A time-domain identification method, the subspace system identification algorithm, is first applied to get a state-space model of the structure. The identified state-space model is then transformed to two special realization forms, for determination of the equation of motion of multiple-degrese-freedom of the structure. The parameters of equation of motion, mass and stiffness matrices or damage indices are used to determine the location and extent of the damage. This method is also extended for the health monitoring of substructural system. Unlike the health monitoring of the whole structure, the health monitoring of substructure uses localized parameter identification which only involves the measurement of substructure parameters. Using this method, the number of unknown parameters and the computational requirement for each identification can be significantly reduced, hence the accuracy of estimation can be improved. Illustrative cases studies using both numerical and experimental structures are presented.