This　study　presents　a　new　dual　time-variant　chloride　diffusion　model　considering　maximum　phenomenon　for　concrete　structures　exposed　to　marine　environment.　The　model　is　developed　from　the　assumption　that　the　concentration　gradient　is　the　sole　or　dominant　driving　force　for　chloride　ingress　in　concrete,　and　both　the　chloride　diffusion　coefficient　and　peak　chloride　content　are　considered　as　time-variant.　The　applicability　and　accuracy　of　the　developed　model　are　verified　by　comparing　the　fitted　and　predicted　chloride　profiles　with　field　data.　Based　on　the　developed　model,　time-variant　probabilistic　evaluation　of　corrosion　initiation　in　a　typical　prestressed　box　girder　located　near　coast　is　carried　out.　Results　reveal　that　the　maximum　phenomenon　has　a　significant　effect　on　the　prediction　of　the　time　to　corrosion　initiation.　The　results　of　sensitivity　analysis　indicate　that　the　critical　chloride　content　is　the　decisive　parameter　in　the　prediction　of　the　corrosion　initiation　time,　followed　by　the　relative　humidity,　water-to-binder　ratio,　temperature,　thickness　of　concrete　cover,　etc.　Besides,　the　effects　of　the　correlation　between　random　variables　and　the　distance　from　the　coast　on　the　time-variant　probability　of　corrosion　initiation　are　investigated.　It　is　found　that　the　correlation　among　random　variables　should　be　considered,　and　the　effect　of　distance　from　the　coast　on　the　time-variant　probability　of　corrosion　initiation　is　sharply　decreasing　at　a　very　short　distance　from　the　coast.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.