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Abstract

It is necessary to develop a calculation method to help in the making of feasible, reliable, and serviceable predictions for the service lives of bridge or viaduct structures. This article presents the basis for doing rust-expansion-crack service life predictions for existing reinforced concrete (RC) bridges and viaducts in chloride-laden environments based on timedependant reliability modeling due to the corrosion of steel in concrete. The corrosion process has three stages, the initiation (diffusion or carbonation) time (ti = tc), the depassivation time (tp), and the propagation (corrosion) time (tcorr). The rustexpansion-crack service lives (tcr) of existing RC bridges or viaducts can be expressed in terms of tcr = tc + tp. Many mathematical models could be applied to calculate each value of tc and tp. The values of tcr may be directly predicted from the relationship between reliability index and time. The existing Wann-fwu bridge and Chorng-ching viaduct in Taipei were provided as illustrative examples for the modeling approach and rust-expansion-crack service life prediction. The results of tcr predicted from the relationship between reliability index and time were in good agreement with the results of tcr calculated from the sum of tc and tp. The results of present study were offered as a decision making for repair, strengthening, and demolition of existing RC bridges or viaducts.

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