For existing reinforced concrete (RC) bridges,the structural performance deteriorates due to corrosion of reinforcing steel,particularly in a polluted environment.The deterioration continues and becomes more significant as time goes by if there is no suitable maintenance.Based on the authors previous study,the corrosion speeds of reinforcing steel corresponding to various degradation stages of RC bridges were obtained in terms of service time.The relationship between corroded depths of reinforcing steel versus service time can be used to take the un-corroded part of steel into account as effective sectional properties for structural analysis.Therefore,the time-dependent structural capacity of deteriorated RC bridge was able to be determined quantitatively.On the other hand,external loading as demand on RC bridges could vary from time to time,e.g.the exceeding live load is frequently happened for traffic requirement.It means that the increasing live load should usually be considered in assessment of structural safety of bridges.