SERVICE LIFE PREDICTION OF PIER FOR THE EXISTING REINFORCED CONCETE BRIDGES IN CHLORIDE-LADEN ENVIRONMENT

The prediction method of service life for bridge structures is played an important role of bridge management system. In this paper, the mathematical modeling was to study the servise life prediction of pier for existing reinforced concrete (RC) bridge exposed to chloride environment. The corrosion process has three stages, the initiation time (t(subscript c)), the depassivation time (t(subscript p)), and the corrosion (propagation) time (t(subscript corr)). The total service life of pier for the existing RC bridge can be expressed as t=t(subscript c)+t(subscript p)+t(subscript corr). Many mathematical models were applied to predicting each value of the t(subscript c), t(subscript p), and t(subscript corr). The Fick's second law, the average of Bazant and Proposed methods, and the modified Bazant method are suggested to estimate the values of t(subscript c), t(subscript p), t(subscript corr), respectively. The Tzyh-chyang and Dah-duh RC bridges in Taiwan were provided illustrative examples for the modeling approaches and service life of predictions. The predicted results used mathematical models may be reasonable for the pier service life of the existing Tzyh-chyang and Dah-duh RC bridges. The results of present study may help to offer a basis for repair, strengthening, and demolition of existing RC bridges.

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