Seismic　retrofit　of　critical　underground　water　pipelines,　serving　as　a　key　component　of　lifeline　networks,　has　become　an　urgent　need　in　engineering　practice　to　improve　the　performance　and　serviceability　of　these　critical　lifelines.　The　corrosion　protection　liner　(CPL)　technology　consists　of　installing　flexible　plastic　liners　with　V-shaped　anchoring　studs　inside　existing　pipelines　and　subsequently　filling　cement　mortar　to　the　gap　between　the　waterproof　liner　and　the　pipeline.　With　the　excellent　chemical　resistance,　impermeability,　and　fast　construction　cycles,　CPL　provides　an　economic　and　environmentally　friendly　alternative　for　pipeline　rehabilitation　without　large-scale　excavation.　However,　the　lack　of　verification　and　quantification　of　the　seismic　performance　of　pipelines　rehabilitated　with　CPL　remains　a　critical　deficiency　for　its　application　as　an　effective　seismic　retrofit　method　for　underground　pipelines.　This　study　focuses　on　the　response　of　CPL-strengthened　ductile　iron　(DI)　push-on　joint　by　evaluating　the　liner　debonding,　relative　joint　openings　produced　by　axial　loadings　simulating　the　seismic　loading　experienced　by　the　pipeline　during　an　earthquake　event.　Full-scale　quasi-static　tests　were　performed　on　two　water-pressurized　DI　pipelines　with　push-on　joints　before　and　after　reinforcement　with　the　CPL.　Moreover,　based　on　the　joint　response　under　quasi-static　loading,　numerical　models　were　developed　for　capturing　the　axial　behaviors　of　CPL-reinforced　joints　that　considers　strength　degradation　and　energy　dissipation.　Both　the　test　results　and　numerical　analyses　indicate　that　CPL　provides　substantial　axial　strength　to　the　joints　of　DI　pipelines　and　improve　their　seismic　behavior　under　high　intensity　ground　motions.　But　the　quality　of　the　heat　melting　welding　of　CPL　remains　a　critical　uncertain　factor,　and　poor-quality　control　may　be　adverse　to　the　seismic　performance　of　the　retrofitted　pipeline.　©　ASCE.