PCCP Condition Assessment: Are Current Numerical Models Too Conservative?

Prestressed concrete cylinder pipes (PCCP) has been used in many large water and wastewater utilities since early 1940s. As it ages, its deterioration continues and the industry is now experiencing more and more PCCP failures. Since most PCCPs are large-diameter pipes with high pressure, their failures could cause catastrophic consequences. To mitigate such failures, it is critical to know the condition of the pipe and take proactive measures such as repair, rehabilitation, or replacement before the pipe fails. In current practice, many numerical models are available for structural analysis of PCCP. However, such models have limitations due to the assumptions that all broken wires have no contribution to structural integrity, thus all broken wires are not considered in the model. Such assumptions could overestimate the damage of broken wires and misjudge “good” pipes as “bad” pipes, causing unnecessary waste of limited funding. This paper presents the validation of a more robust numerical model that could consider the structural contribution of broken wires. The field data of a 48-inch PCCP from Washington Suburban Sanitary Commission (WSSC) was collected and used for model validation. The results show that the model can simulate PCCP’s actual failure very well, demonstrating its good applicability in real practice. This model can be used in practice for more effective management of PCCP pipelines.