Experimental Study on the Longitudinal Strain Behavior of Cured-in-Place Pipe Liners Crossing Joints in Reinforced Concrete Culverts

Abstract

The structural integrity and durability of culverts, such as reinforced concrete pipes (RCPs), are significant concerns as aging stormwater systems deteriorate over time. Trenchless rehabilitation techniques, particularly Cured-in-Place Pipe (CIPP) liners, have emerged as efficient alternatives to complete pipe replacement. Despite their widespread use, a notable gap exists in the technical literature concerning the longitudinal response of pipe–liner composite systems, particularly at joints subjected to rotation. Current design standards offer no guidance on how these systems respond mechanically under such conditions. This study addresses this gap by conducting experiments on lined buried RCPs subjected to AASHTO live loads at a 60 cm cover depth, quantifying bending performance and joint rotation behavior under single axle loading. Results showed that joint rotation increased proportionally with applied load, reflecting a consistent elastic response. Strain measurements at the invert confirmed tensile behavior with maximum strain at the joint, identifying it as the critical location. Even under extreme loading, nearly seven times the service load, no damage occurred in either the liner or host pipe, and strain levels indicated that ring fractures are unlikely, demonstrating the robust performance of the lined system. Additionally, the study confirms the validity of the design equation proposed by Zhai and Moore (2024), as measured strains closely matched predictions under service loads. These findings provide insight into the structural performance of CIPP liners across joints and contribute to the management of a potential design limit state that has not previously been addressed.