Experimental Study on Mechanical and Sensing Properties of Smart Composite Prestressed Tendon

It is typically difficult for engineers to detect the tension force of prestressed tendons in concrete structures. In this study, a smart bar is fabricated by embedding a Fiber Bragg Grating (FBG) in conjunction with its communication fiber into a composite bar surrounded by carbon fibers. Subsequently, a smart composite cable is twisted by using six outer steel wires and the smart bar. Given the embedded FBG, the proposed composite cable simultaneously provides two functions, namely withstanding tension force and self-sensing the stress state. It can be potentially used as an alternative to a prestressing reinforcement tendon for prestressed concrete (PC), and thereby provide a solution to detecting the stress state of the prestressing reinforcement tendons during construction and operation. In the study, both the mechanical properties and sensing performance of the proposed composite cable are investigated by experimental studies under different force standing conditions. These conditions are similar to those of ordinary prestressed tendons of a real PC components in service or in a construction stage. The results indicate that the proposed smart composite cable under the action of ultra-high pretension stress exhibits reliable mechanical performance and sensing performance, and can be used as a prestressed tendon in prestressed concrete structures.