ABSTRACT
As the prestressing tendons are the key component of prestressed concrete (PSC) bridges, it is of great significance to monitor the stress status of prestressed tendons for PSC bridges. Existing testing methods, how-ever, are difficult to effectively monitor the stress of bonded tendons. The elasto-magnetic (EM) sensor is a new nondestructive and noncontact measurement technology for cable force, which has been widely used in the Chinese bridges for construction control of prestressed tendons and on-line monitoring during the service period of bridges. The testing principle, performance and characteristics of EM sensors are introduced in this paper. Then the application of EM sensors to measure the bonded prestressing tendons of PSC bridges is de-scribed in detail. Moreover, based on the experiment of long-term prestress loss monitored by EM sensor, the influences of duct grouting, transverse stirrups and stress level on the long-term loss are discussed. Finally, a real-time cable force monitoring system based on EM sensor is established. The research results can provide reference for the prestress monitoring of other similar bridges.
