Monitoring the circumferential cracking of inner concrete core in prestressed concrete cylinder pipe during wire-wrapping using distributed optical fiber sensors

Abstract

In the manufacturing process of prestressed concrete cylinder pipe (PCCP), circumferential cracks often manifest in the inner concrete core. It poses a potential risk of pipe failure in engineering applications. This paper introduces the utilization of distributed optical fiber sensors for monitoring the circumferential cracking in the inner concrete core in PCCP. A test specimen, featuring a double-layer wrapping structure with an inner diameter of 3.40 m and a length of 5.00 m, was monitored during the wire-wrapping and lifting processes. The results reveal that the circumferential crack is positioned 0.20 m away from the top of the spigot after the second wire-wrapping. This location corresponds to the welding point of the spigot steel ring and the steel plate, situated within the tensile stress zone induced by the wire-wrapped zone. The primary cause for the cracking is stress concentration resulting from the abrupt profile change at the joint of the spigot steel ring and the steel plate. Notably, the lifting process exerts a negligible influence on circumferential cracking. The strains of the steel cylinder and concrete before and after the wire-wrapping process consistently exhibit elastic behavior.