ABSTRACT
Prestressing is the decisive component for achieving large spans with concrete bridges. For the long-term preservation of prestressed concrete bridges, the early detection of damage to tendons is particularly important. As tendons are often located within the concrete, the assessment of their condition is difficult with conventional methods. Ultrasonic measurements with sensors embedded in the concrete and evaluated with coda wave interferometry offer a promising new approach for assessing the internal health of concrete structures. To demonstrate the detection of tendon failures, two experiments—one with pre-tensioning and one with post-tensioning—were carried out at Ruhr University Bochum, Germany. By simulating a tendon failure, the prestressing force drops abruptly. The experimental results prove that the coda technique detects such tendon failures unambiguously, although no external changes seem to have appeared.
