Innovative Approach to Estimate Prestressed Concrete Cylinder Pipe Remaining Useful Life

Prestressed Concrete Cylinder Pipe (PCCP) is widely used to construct large-diameter transmission and feeder Watermains. These assets usually have a high consequence and/or impact of failure, and any unexpected service interruptions from a PCCP failure may place a significant burden on the pipe owner. Hence, it is paramount to inspect and assess PCCP assets using state-of-the-art technologies to estimate the physical condition of the PCCP asset. However, these inspections are a snapshot in time and only provide valuable information on the current physical condition of the PCCP asset. Hence, these inspection results should be leveraged to estimate the PCCP’s remaining useful life (RUL) to aid in making sound decisions in-line with the pipe owner asset management framework. Estimating PCCP’s remaining useful life is a complex process and involves multiple stages given the nature of the PCCP structure that acts as a composite structure. These stages are well-documented in the industry and are associated with different structural limit states (serviceability, yield, and strength limit states) as per the AWWA C304. Hence, to estimate the RUL, an innovative approach was developed that involved developing multiple survivor curves associated with each structural limit state by fitting the best distribution model with an estimated deterioration curve based on prestressing wire count technology. The paper will demonstrate that the methodology of a 36 in. PCCP (LCP type) was assessed using risk margin technology that assessed the prestressing wire break thresholds associated with the different structural limit states (serviceability, yield, and strength limit states) as per AWWA C304. An inspection of the 36 in. PCCP using prestressing wire count technology was plotted on the developed multiple survivor curves and its estimated RUL was estimated based on the current inspected distress status, age, and projecting the time to reach the strength limit state using the multiple surviving curves’ methodology.