Abstract:  The mechanism of concrete carbonization and the model of carbonization depth of reinforced concrete structures were discussed‚and a formula of concrete carbonization depth suitable for reliability analysis of existing reinforced concrete bridges was given．Then‚taking the state while concrete carbonization develops to the surface of the reinforcement as the durability limit state‚and taking the present time as the analysis starting point‚models of reliability analysis and residual lifetime prediction of
concrete carbonization are established‚and their practical approximate calculation methods are presented．Finally‚taking a actual reinforced concrete bridge for example‚the reliability of carbonization and residual carbonization lifetime of the bridge were estimated．Reference basis for maintenance decision of the bridge was provided．

Key words: existing reinforced concrete bridge, concrete carbonization, reliability assessment, residual lifetime prediction