| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 95 === Generally speaking, structure needs long-term use, aside from elaborating about accuracy, quality, and suitability in the process of design, construction, and implementation management, repair and strengthening are very important afterwards. Owing to the Taiwan is an island-type climate, structures are severely subjected to chloride ingression. The service life of structure is reduced by the influence of carbonation of concrete. The main propose of this article was to study the service lives of existing reinforced concrete（RC）bridges separately due to chloride-ion and carbonation. When considering the service life of existing RC bridge induced by the chloride-ion penetration, the service life（t） is divided into three stages：initiation period （tc）, depassivation period （tp）and propagation period （tcorr）, i.e. t= tc + tp + tcorr. Some mathematical models are used to predict the values of tc, tp, and tcorr. Both the Tzyh-chyang and Dah-duh bridges were used as illustrative examples for verifying the mathematical models. The corresponding service lives prediction are 58.82 and 56.01 years, respectively. As to the influence of carbonation to existing RC bridge, the random model associated with reliability analysis is employed to predict carbonation life. Meanwhile, the field test data of the Chorng-ching viaduct, Wann-fwu bridge, and Shi-yuan viaduct are used to predict their carbonation lives. When the reliability index is zero, their carbonation life-time are 55, 55, and 60 years, respectively. The present study results can be extended and applied to predict the service lives, repair, and strengthening of existing RC bridges.
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