Contact　explosion　due　to　military　and　terrorist　attacks　present　a　significant　threat　to　bridge　safety.　In　the　context　of　frequent　regional　conflicts　and　terrorist　incidents　worldwide,　it　is　essential　to　investigate　the　damage　mechanism　and　fragility　of　bridges　subjected　to　contact　explosion.　In　the　present　study,　a　three-span　reinforced　concrete　(RC)　continuous　box　girder　bridge,　scaled　down　to　1/4　of　its　original　size,　was　tested　by　subjecting　the　deck　to　contact　detonation.　The　damage　mechanisms　and　the　effects　of　explosion　location　on　the　deck　were　studied.　The　experimental　results　were　then　used　to　validate　the　FE　model　established　using　LS-DYNA,　comprehensively　verifying　the　model＇s　reliability　in　predicting　damage,　dynamic　response,　and　residual　flexural　resistance.　A　quantitative　post-blast　performance　assessment　method　was　developed　based　on　residual　flexural　resistance　obtained　by　numerically　simulating　four-point　bending　tests.　Driven　by　results　generated　from　FE　models,　a　surrogate　model　is　developed　for　estimating　the　post-blast　performance　with　negligible　computation　cost.　This　surrogate　model　is　employed　to　develop　fragility　curves　using　Monte　Carlo　simulations　(MCS),　considering　uncertainty　in　detonation　location　and　variability　in　TNT　charge　mass.　Consequently,　the　damage　probability　of　the　bridge　was　estimated　under　both　military　objective　(MO)　and　collateral　damage　estimation　(CDE)　scenarios.　Four　weapon　guidance　and　a　wide　range　of　TNT　charge　mass　(0-750　kg)　were　adopted.　The　results　provide　insights　into　the　damage　mechanisms　of　box　girder　bridges　subjected　to　contact　explosions　and　offer　blast　fragility　curves　to　quantify　damage　probability.