This　paper　investigates　the　mechanical　performance　of　ultra-high-performance　concrete　(UHPC)　beam-to-beam　joints　in　steel–concrete　composite　bridges,　proposing　an　alternative　to　conventional　reinforced　concrete　(RC)　joints　in　continuous　beams.　The　authors　employed　UHPC　with　steel　end-plates　and　studs　to　connect　the　UHPC　crossbeam　with　the　steel　beams　and　RC　slab.　These　connections　provides　advantages　like　eliminating　the　need　for　on-site　welding,　simplifying　construction,　and　handling　potential　tolerance　issues.　The　research　includes　full-scale　experimental　tests,　a　benchmark　test　on　an　RC　joint,　validation　of　finite　element　models,　parametric　analyses,　and　the　development　of　analytical　models　to　predict　the　joint＇s　moment–rotation　curve,　initial　stiffness,　and　ultimate　bending　capacity.　Full-scale　experiments　revealed　that　the　maximum　longitudinal　concrete　stress　in　UHPC　continuity　joints　occurs　at　the　interface　between　the　composite　steel–concrete　beam　and　the　UHPC　cross-beams,　resulting　in　crack　widths　substantially　below　code　limits.　The　parametric　analyses　identified　critical　factors　affecting　UHPC　joint　performance,　such　as　concrete　strength,　steel　yield　strength,　and　horizontal　stud　dimensions.　Additionally,　the　study　validated　existing　formulations　for　predicting　the　capacity　and　stiffness　of　the　joints　against　the　results　from　the　finite　element　(FE)　parametric　analyses.　©　2024　The　Author(s)