Detection of internal tendon breaks by fiber-optical measurements on concrete surfaces

Abstract

Undetected internal tendon breaks pose a great risk for prestressed concrete structures. The failure of single tendons does not necessarily cause the formation of surface cracks. Hence, demolition and re-construction are often the consequence. This article presents an experimental method for detecting and localizing such damage using fiber-optic measurements. As a result of the loss of prestress and the re-anchoring of the tendon in the surrounding concrete, characteristic changes occur in the strain field on the concrete surface. These are detected using a two-dimensional grid of fiber-optic sensors.