Application of fiber optical and resistance strain gauges for long-term surveillance of civil engineering structures

We report on applications of surveillance and test systems for civil engineering structures. The system key elements are optical-fiber Bragg grating sensors and conventional resistance strain gauges. A recently built stay cable bridge with a world novelty of two carbon-fiber-reinforced-polymer cables was equipped with both types of sensors (Storck's Bridge in Winterthur, Switzerland). The sensor system on the bridge is now operational for ten months and the bridge is open for traffic for 4 months. Results of the bridge surveillance are presented. To monitor a large concrete structure, the electrical power dam of Luzzone in the Swiss Alps, a prototype sensor rod was designed. First measurements with a sensor rod embedded in a concrete test prism are discussed. Several redundant measurements are made to compensate for temperature drift and to monitor the reliability of the measurement chain.