This　paper　investigates　the　behavior　of　Warren-vertical　CFT　truss　girders　by　conducting　both　experimental　tests　and　finite　element　analyses.　Experimental　tests　on　three　CFT　truss　girders　are　first　conducted.　The　test　parameter　is　the　compressive　strength　of　the　concrete　infill.　Finite　element　models,　which　were　developed　and　bench　marked　previously　by　the　authors,　are　then　used　to　further　investigate　the　behavior　of　CFT　truss　girders　and　the　influence　of　parameters　such　as　the　brace-to-chord　strength　ratio,　shear　span-to-depth　ratio,　and　concrete　compressive　strength.　Results　from　the　parametric　studies　indicate　that　CFT　truss　girders　are　flexure　dominated　if　(i)　the　brace-to-chord　strength　ratio　＞=　0.8　and　(ii)　the　shear　span-to-depth　ratio　＞=　4.8.　Both　the　experimental　tests　and　FEM　analyses　indicate　that　the　concrete　compressive　strength　has　negligible　effects　on　the　failure　mode　of　CFT　truss　girders.　Based　on　results　from　the　experimental　tests　and　FEM　analyses,　design　equations　are　also　proposed　for　estimating　the　flexural　strength　of　Warren-vertical　CFT　truss　girders.