Strengthening of PCCP with broken wires using prestressed CFRP

Abstract

With increasing years of service, prestressed concrete cylinder pipes (PCCP) can be damaged due to wire breakage. Burst can then occur in the pipeline, resulting in loss of water resources. For main water diversion projects, water supply in pipelines cannot be interrupted, and as such repair for damaged pipe segments can become difficult. This study proposes an innovative retrofitting technique of using externally bonded prestressed carbon fiber reinforced polymer (CFRP) to repair damaged PCCP with broken wires. A three-dimensional (3D) PCCP model is established. Upon the successful reproduction of experimental measurements, the numerical model is used to simulate the effects of prestress level, number of CFRP layers, and wire breakage ratio. The results show that the developed approach could strengthen the resistance of PCCP by at least 28.6%, 36.7%, 19.8% and 16.1% as an interpretation of the stress–strain analyses for inner concrete core, outer concrete core, steel cylinder and steel wires, respectively. A damaged PCCP with a wire breakage ratio of less than 25% can remain in service, after it is strengthened by four layers of CFRP at a prestress level of 40%.