Ultra-high　performance　manufactured　sand　concrete　(UHPMC),　using　manufactured　sand　(MS)　as　aggregate,　belongs　to　a　brand-new　ultra-high　performance　concrete　(UHPC).　Better　understanding　the　failure　behavior　of　UHPMC　beams　reinforced　with　steel　reinforcement　bars　is　crucial　in　structural　design.　This　study　investigates　the　effects　of　different　shear　span-to-depth　ratios　(λ　=　1.2,　1.6　and　2.0)　on　the　failure　modes,　mid-span　deflection,　concrete　and　rebar　strain,　flexural　toughness,　initial　cracking　load,　ultimate　load,　energy　dissipation　capacity,　and　crack　propagation　patterns　based　on　four-point　bending　tests　for　totally　twelve　reinforced　UHPMC　beams.　Meanwhile,　acoustic　emission　(AE)　monitoring　is　used　to　evaluate　corresponding　fracture　characteristics.　Results　reveal　that　an　increase　in　shear　span-to-depth　ratio　leads　to　a　significant　increase　in　mid-span　strain　and　better　ductility　but　lower　equivalent　stiffness.　The　maximum　strain　of　specimen　with　λ　=　1.2　is　24.8　%　lower　than　that　with　λ　=　2.0,　and　specimen　with　λ　=　1.6　exhibits　22.3　%　greater　equivalent　stiffness　than　that　with　λ　=　2.0.　Beams　with　larger　shear　span-to-depth　ratios　demonstrate　superior　ductility　and　energy　absorption　capacity,　specimen　with　λ　=　2.0　showing　a　ductility　factor　2.85　times　higher　than　that　with　λ　=　1.2.　The　presence　of　MS　significantly　improves　initial　cracking　load　by　26.9　%,　ultimate　load　by　4.5　%,　and　energy　dissipation　capacity　by　37　%.　MS　also　enhances　toughness　and　delays　crack　propagation　in　the　early　stages.　This　effect　can　make　the　fracture　transform　into　more　rapid　energy　release　in　the　later　stages,　indicating　that　MS　could　alter　crack　propagation　patterns,　forcing　cracks　to　propagate　along　paths　with　greater　resistance　to　crack　propagation.　These　conclusions　can　offer　insights　for　the　safer　and　economical　design　and　application　of　UHPMC　beams,　especially　the　balance　among　shear　span-to-depth　ratio,　MS　and　mechanical　performance　in　the　environmentally　friendly　structures　design　and　failure　prevention　process.　©　2024　Elsevier　Ltd