Implementation of a SHM method on a numerical model of a cable-stayed bridge

This paper discusses the implementation of a structural health monitoring (SHM) technique on a numerical model of the Bill Emerson Memorial bridge. The method uses the natural excitation technique (NExT) and the eigensystem realization algorithm (ERA) to identify the modal parameters of the structure. A least squares solution of the eigenvalue problem is used to detect elemental structural parameters from the identified modal parameters. Damage is identified by comparing the elemental parameters before and after damage. It is found that the singular values of the Hankel matrix are not a reliable approach to determine the number of modal parameters identified with the ERA for this type of structure. A variation of the method is used to differentiate between computational values due to noise and numerical errors and those representing the structural characteristics.