Monitoring Damage in PC Slabs by Modal and Ultrasonic Tests
Keywords:damage detection, damping, natural frequency, nondestructive test, prestressed concrete, ultrasonic, pulse velocity
The effectiveness of modal and ultrasonic tests for monitoring the damage in precast prestressed concrete slabs was experimentally investigated. Four slabs with two different span lengths and corresponding modes of failure (interfacial shear and flexural failures) were subjected to loading steps until failure. The variations in fundamental natural frequency, damping ratio, ultrasonic pulse velocity (UPV), and ultrasonic wave attenuation in relation to the damage severity and failure mode were investigated and compared. It was observed that the natural frequency was sensitive to flexural crack development. A significant change in the damping ratio was obtained in the slabs with moderate damage. The UPV was not affected by a moderate degree of interfacial shear damage and a low degree of flexural damage; however, it was strongly related to the progression of flexural damage at the severe stage. Among the various indexes, ultrasonic wave attenuation was most sensitive to the development of damage. The method could detect interfacial-shear and flexural cracks at an early stage.
Authors who publish with Engineering Journal agree to transfer all copyright rights in and to the above work to the Engineering Journal (EJ)'s Editorial Board so that EJ's Editorial Board shall have the right to publish the work for nonprofit use in any media or form. In return, authors retain: (1) all proprietary rights other than copyright; (2) re-use of all or part of the above paper in their other work; (3) right to reproduce or authorize others to reproduce the above paper for authors' personal use or for company use if the source and EJ's copyright notice is indicated, and if the reproduction is not made for the purpose of sale.