To　solve　the　problem　of　low　accuracy　caused　by　only　a　single　typical　component　which　is　selected　to　represent　the　overall　vulnerability　in　the　traditional　analysis,　continuous　beam　bridge　is　assumed　as　a　ternary　system　composed　of　pier,　abutment　bearing　and　pier　bearing.　The　damage　degree　of　corresponding　components　is　quantified　by　pier　end　curvature　or　damage　index　based　on　elastic-plastic　energy　dissipation　difference　and　bearing　displacement,　and　then　the　vulnerability　analysis　of　components　is　carried　out.　Multivariate　Copula　function　was　introduced.　On　the　basis　of　calculating　the　vulnerability　curve　of　the　main　components,　the　method　to　solving　the　seismic　vulnerability　of　the　ternary　component　system　was　established.　©　Published　under　licence　by　IOP　Publishing　Ltd.