For the purpose of the degradation assessment of concrete bridges in life-cycle,a finite element-based methodology for the degradation process of concrete bridges is proposed.This is done by:(a) the computation formulas of the three critical times;and(b) the simulation methods of several special mechanics problems in the degradation process.Based on the theoretical analysis,a program named CBDAS is written in FORTRAN 95.The research on the variation of structural performance in given service life with chloride penetration is carried out by means of a reinforced concrete continuous girder bridge.The results show that: the initiation time of reinforcement corrosion is early and the corrosion rate is fast with chloride penetration.In 80 years after structure completion,bending capacities are smaller than the relative envelope moments at two critical sections for the ultimate limit state.As a result,as for the reinforced concrete bridges,the ultimate limit states are more likely to have durability defects.