Service Life Prediction of Existing Reinforced Concrete Bridges Exposed to Chloride Environment

There is a need to develop a calculation method to aid in the making of reliable predictions for the service life of bridge structures. This paper examines the basis for making service life predictions for existing reinforced concrete (RC) bridges in chloride-laden environments based on mathematical modeling. The corrosion process has two stages, the initiation time (t1) including depassivation time (tp) and the corrosion (propagation) time (tcor). The total service life of existing RC bridges can be expressed as t=t1+tcor. Many mathematical models were applied to calculate each t1 and tcor. The AJMF (2) and modified Bazant methods are suggested to estimate the values of t1 and tcor, respectively. The Chung-shan Bridge, 69 years old, in Taipei, was offered as an illustrative example for the modeling approach and service life predictions. The predicted results, such as B, E, F, and H zones, for the service life of the old Chung-shan Bridge using the proposed method showed that it is serviceable and reliable compared with measured damage. The results of this study were provided as a basis for repair, reinforcement, and demolition of existing RC bridges.