Ninety-percent of California's bridges are post-tensioned concrete structures. There is a need to develop technologies able to monitor the state of health of the prestressing tendons which carry most of the loads. Recent bridge collapses have further highlighted the problem of the deteriorating conditions of the transportation infrastructure which require information on weak components.
Professor Lanza di Scalea and post-doctorals Ivan Bartoli and Salvatore Salamone are working with Caltrans to develop an ultrasonic-based monitoring system for the prestressing tendons of post-tensioned concrete structures. The method is based on embedded sensors and ultrasonic guided waves which can provide information on the level of stress as well as the presence of defects such as corrosion or broken wires. Laboratory tests have indicated the suitability of the guided-wave method to achieve these goals. If further laboratory tests are favorable, the tendon monitoring system will be installed and tested on an operational post-tensioned bridge in California.