Continuous acoustic monitoring of grouted post-tensioned concrete bridges

The paper describes the first UK site installation of a monitoring system t hat detects the fracture of wires in post-tensioning tendons by listening w ith acoustic sensors attached to the surface of the concrete. Trials have s hown the system to work reliably for grouted and ungrouted tendons. Acousti c events from other sources such as road traffic are discarded using softwa re and hardware filters at the unattended site. Data from possible wire-fra cture events are sent off site for final identification and positioning. Th e system is running continuously on site, on a viaduct, with close to 100% up-time. In open and blind trials on the viaduct, 41 out of 44 wire break o r facsimile events were correctly located and identified and a further two were correctly located. The system can assist in the management of bridges where the posttensioning system is at risk from corrosion. (C) 2001 Publish ed by Elsevier Science Ltd.