Experimental Investigation on Mechanical Response of Rehabilitated Pipelines under Cyclic Axial Deformation

Legacy pipelines face challenges related to seasonal temperature change. The thermomechanical loading results in axial deformation and stress, especially concentrated at weak joints. Understanding the mechanical response of rehabilitated pipelines aids in the successful design of lining. This study presents variations in the force–deformation curves, elastic modulus, and irreversible strain values under displacement-controlled cyclic axial loading. Experimental tests measure the behavior of steel–cured-in-place-pipe (CIPP) host-repair specimen, featuring a full circumferential crack where the CIPP is exposed. An analytical approach based on elasticity theory was conducted to study the structure’s behavior and estimate potential levels of stiffness degradation. Results showed that the stiffness degradation process gradually occurs after each cycle of loading with interaction of several parameters. Debonding process and residual plastic strains are the most important parameters affecting stiffness degradation. Both full-scale experimental test and analytical method showed reasonable consistency in determining the mechanical properties of cured pipelines.