Structural deterioration after a period of service can induce the failure of prestressed concrete cylinder pipes (PCCPs), with\nmicrocracks in the coating leading to the corrosion of the prestressed wires. In this paper, we propose the use of Brillouin optical\ntime-domain analysis (BOTDA) strain sensors for detecting the onset of microcracking in PCCP coating: the BOTDAstrain sensors\nare mounted on the surface of the PCCP, and distributed strain measurements are employed to assess the cracks in the mortar\ncoating and the structural state of the pipe. To validate the feasibility of the proposed approach, experimental investigations were\nconducted on a prototype PCCP segment, wherein the inner pressure was gradually increased to 1.6MPa. Two types of BOTDA\nstrain sensorsââ?¬â?the steel wire packaged fiber optic sensor and the polyelastic packaged fiber optic sensorââ?¬â?were employed in the\nexperiments. The experimental distributed measurements agreed well with the finite element computations, evidencing that the\ninvestigated strain sensors are sensitive to localized deterioration behaviors such as PCCP microcracking.
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