Using EPS and CFRP Liner to Strengthen Prestressed Concrete Cylinder Pipe

The prestressed concrete cylinder pipe (PCCP) with broken wires should be strengthened to maintain the safe operation of the pipeline. A new reinforcement technology is proposed in this study: expanded polystyrene (EPS) + carbon fiber reinforced polymer (CFRP) liner. The innovative method allows CFRP to bear the internal pressure prior to PCCP, greatly improving the reinforcement effect of the pipe. A three-dimensional finite element model is established and assessed by the experimental results. Then, the mechanical properties of the PCCP when subjected to different pressures and wire breakage are analyzed under three conditions (i.e. no strengthen, strengthened by only CFRP liner, and strengthened by EPS+CFRP liner). And the improvement effect of the innovative technology on the PCCP's bearing capacity compared with the traditional method is studied. The results showed that when repaired by 8-layer CFRP liner only and EPS and 6-layer CFRP composite liner, the internal pressure bearing capacity of PCCP can be increased by 9.17% and 50.83%, respectively. Based on the elastic limit state of the pipe, the wire breakage threshold of PCCP is 65 and 89 under the cases of no repair and CFRP liner repair. For the case of EPS + CFRP liner repair, when the number of broken wires is 100, the steel cylinder does not yield.