Longitudinal　equivalent　bending　stiffness　(LEBS)　is　a　fundamental　parameter　of　shield　tunnels,　which　directly　affects　the　longitudinal　response　analysis.　The　influence　of　axial　force　and　bending　moment　on　the　LEBS　of　the　shield　tunnel　has　not　been　well　considered　through　model　test　in　existing　studies.　Therefore,　a　large-scale　model　test　for　circumferential　joints　was　conducted　in　this　study.　The　model　lining　was　fabricated　by　3D　printed　photosensitive　resin　and　aluminium　alloy　rod.　The　test　apparatus　was　specially　designed　and　assembled　to　measure　the　LEBS　under　different　axial　forces.　Five　model　tests　were　conducted　to　discuss　the　influences　of　axial　force　and　bending　moment　on　the　LEBS.　Meanwhile,　the　test　results　were　validated　via　a　series　of　numerical　simulations　upon　the　ABAQUS　platform.　Some　conclusions　can　be　summarized　as　follows:　The　LEBS　varied　nonlinearly　with　the　bending　moment,　which　could　be　divided　into　three　stages.　In　the　static　resistance　stage,　the　bending　moment　was　mainly　carried　by　the　axial　force,　which　led　to　a　great　value　of　LEBS.　In　the　elastic　bending　stage,　the　bending　moment　was　carried　by　the　axial　force　and　bolts　jointly;　the　LEBS　decreased　rapidly　with　bending　moment.　In　the　plastic　bending　stage,　the　LEBS　decreased　slowly　with　bending　moment　and　converged　to　its　steady　value.　The　quantitative　influence　of　bending　moment　and　axial　force　on　LEBS　could　be　fitted　by　Logistic　function.　Conveniently,　the　longitudinal　bending　stiffness　efficiency　η　increased　exponentially　with　the　axial　force　nonlinearly.　In　the　model　test,　the　η　ranged　from　6.08　%　to　16.82　%　when　N　was　within　0–9.2　MN.　The　η　ranged　from　5.77　%　to　25.11　%　when　N　was　within　0–10　MN　in　the　numerical　simulation.　These　researches　could　provide　some　references　for　the　longitudinal　deformation　estimation　and　the　lining　design　of　shield　tunnel.　©　2025　Institution　of　Structural　Engineers