Abstract:A probabilisticand finite elementbased lifetime performance assessment method is proposed.A durability analysis program named concrete bridge durability analysis system(CBDAS) is written based on the numerical simulation methods relating to the deterioration of materials properties,reduction of sectional areas,and variation of structural performance.Then the statistical parameters of the random variables involved in the assessment of structural lifetime performance are recommended according to the present studies.Thus,the timevariant system reliability assessment method of reinforced concrete bridges is set up based on CBDAS and MonteCarlo simulations.Finally,the lifetime performance of a reinforced concrete continuous bridge under chloride penetration is investigated by means of the timevariant system reliability.