Performance Monitoring of Extreme Large-Diameter Prestressed Concrete Cylinder Pipe with Distributed Fiber Optic Sensors

A method based on the distributed fiber optic strain sensors is presented to monitor the structural performance of the extreme large diameter prestressed concrete cylinder pipes (PCCPs). The distributed sensors are proposed to mount on the surface of PCCP, and their readings are used to evaluate the cracking of the mortar cover and structural behavior of PCCP. To verify the feasibility of the proposed method, a series of prototype tests were performed on a large diameter PCCP (DN3800×5000/P0.6) with internal water pressure up to 1.6 MPa. Two kinds of distributed fiber optic sensors, i.e. steel wire strengthened strain cable (SWSC) and poly-elastic strain cable (PESC), were used in the tests. The surface bonding and embedding approaches were investigated for sensor installation in the experiments. The distributed measurements were in good agreement with the numerical simulations. When the internal pressure reached 1.0 MPa, the mortar cracking was detected from the distributed strain measurements with PESCs. It indicates that the distributed fiber optic strain sensors would not miss the localized behavior, such as cracking, that the conventional strain gauges cannot detect. The experimental results demonstrate that the distributed fiber optic sensors can provide the warning sign of early damage in large diameter PCCP.