The　composite　RC　(reinforcement　concrete)　beam　featuring　ultra-　high　performance　concrete　(UHPC)　butterfly　webs　represents　an　innovative　structural　design　that　combines　the　strengths　of　both　RC　and　UHPC　materials.　It　exhibits　considerable　potential　for　applications　in　arch　bridges.　This　paper　presents　the　outcomes　of　a　trial　design　involving　a　composite　RC　structure　with　UHPC　butterfly　webs.　Subsequently,　it　conducts　a　preliminary　analysis　of　the　mechanical　behavior　of　this　composite　RC　beam　with　UHPC　butterfly　webs　un　der　axial　and　shear　forces.　The　study　evaluates　the　effects　of　various　parame　ters,　including　the　dimensions　of　the　butterfly　web,　ratio　of　axial　compression　stress　to　strength,　ratio　of　shear　span　to　depth,　and　reinforcement　of　web,　using　finite　element　software　(ABAQUS).　The　results　indicate　that　the　mechanical　behavior　of　the　composite　beam　is　significantly　influenced　by　the　parameter　of　the　butterfly　web.　Remarkably,　the　shear　capacity　of　the　composite　beam　in　creased　within　the　angle　ranged　of　50°　to　70°,　the　thickness　ranged　of　40 mm　to　90 mm,　and　the　width-to-height　ratio　ranged　of　0.9　to　1.1.　Furthermore,　the　shear　capacity　of　the　composite　beam　can　be　effectively　enhanced　by　optimizing　the　ratio　of　axial　compression　stress　to　strength　and　by　designing　an　appropriate　reinforcement　configuration.　It’s　important　to　note　that　decreasing　the　ratio　of　shear　span　to　depth　led　to　a　more　pronounced　brittle　failure　mode　in　the　composite　beam,　but　is　also　resulted　in　an　increased　shear　capacity.　©　The　Author(s),　under　exclusive　license　to　Springer　Nature　Switzerland　AG　2025.