Orthotropic　steel　decks　are　vulnerable　to　fatigue　cracking　in　welded　connections　and　complex　geometrical　details.　A　total　of　three　fatigue　tests　were　conducted　on　segments　of　orthotropic　steel　deck　to　evaluate　the　fatigue　performance　of　trough-to-crossbeam　connections　with　various　cut-out　configurations.　In　the　tests,　the　specimens　were　subjected　to　cyclic　three-point　bending　load　and　the　fatigue　cracks　were　more　likely　to　initiate　from　the　cope　holes　in　the　crossbeam　web　rather　than　the　trough-to-crossbeam　fillet　welds.　Three-dimensional　finite　element　models　(FEM)　of　the　specimens　were　built　and　validated　by　the　measured　deflections　and　stresses.　Using　the　validated　FEM,　the　characteristic　stresses　based　on　the　theory　of　critical　distances　(TCD)　were　calculated　for　the　stress　concentrations　along　the　cope　holes.　The　fatigue　crack　initiation　life,　predicted　by　the　TCD-based　stress　combined　with　the　plain　material　S-N　curve,　agreed　reasonably　with　the　fatigue　test　results.　The　TCD　method　could　further　form　a　basis　of　fatigue　crack　propagation　analysis　using　the　fracture　mechanics　approaches.