Amid　frequent　global　conflicts　and　terrorist　attacks,　normal　concrete　reinforced　(NRC)　box　girder　bridges　are　increasingly　vulnerable　to　contact　explosions,　underscoring　the　necessity　of　thoroughly　investigating　their　damage　mechanisms.　This　paper　presents　the　results　of　a　6　kg　TNT　above-deck　contact　explosion　test　conducted　on　a　bridge　model,　scaled　down　to　1/4　of　its　original　size.　A　numerical　model　was　developed　using　LS-DYNA,　and　its　accuracy　was　validated　by　comparison　with　experimental　results.　By　analyzing　the　interaction　between　shock　waves　and　the　structure,　as　well　as　stress　wave　propagation,　the　damage　mechanisms　were　comprehensively　revealed.　Further　parametric　analysis　explored　the　effect　of　blast　intensity　and　concrete　strength　on　the　damage.　Results　indicate　that　within　a　specific　range　of　blast　intensities,　localized　damage　is　the　predominant　damage　mode　for　the　bridge.　As　blast　intensity　increases,　the　severity　and　complexity　of　these　localized　damages　also　intensify.　When　the　blast　intensity　exceeds　the　critical　level,　shear　failure　of　the　bottom　slab　emerges　as　the　dominant　mode.　Concrete　strength　can　influence　both　the　extent　of　localized　damage　and　the　critical　blast　intensity.