Experimental Investigation of System-Identification-Based Damage Assessment on Structures

Damage assessment algorithms based on the system identification (SI) method are examined through laboratory experiments. The SI method considered herein identifies structural parameters in a finite-element model by minimizing the error between measured and analytically computed responses. A regularization scheme is applied to alleviate the ill-posedness of an inverse problem by adding a regularization function to the primary error function. Two different algorithms depending on the type of measured response have been developed to assess damage. Static displacements from static loading and modal data from impact vibration were measured through laboratory experiments on a grid-type model bridge. The baseline structural model and baseline properties are determined with experimental data obtained from the tests on the undamaged model structure. Damage is simulated by saw cutting the cross section with various depths and identified as the reduction in the structural stiffness of the elements around the crack. Through the experimental works, the applicability of the SI-based damage assessment algorithms has been rigorously investigated.