This paper presents a numerical scheme to estimate a residual fatigue life of damaged RC bridge decks by means of the pseudo-cracking method proposed, which converts crack inspection data into the on-site mechanistic damage of structural concrete. First, crack information, which can be obtained through a simple visual inspection at site, is transformed to equivalent strain fields upon a finite element discretization, and an equivalent damage state is numerically reproduced. Then, the proposed system simulates subsequent responses to assess the residual fatigue life despite the initial cause of the cracks. The methodology proposed in this study was examined by re-producing several inspection processes computationally, and the numbers of traffic load passages at failure is verified without using the past loading history. For engineering verification, the fatigue-loading experiment of RC slabs, which was taken from a bridge subjected to the real traffic loads, are targeted to be simulated by the pseudo-cracking approach. Sensitivity analyses are also conducted to compute the S-N diagram of the damaged slabs in the five deterioration grades specified by the JSCE maintenance code, and the quantitative results are found to approximately match the specified recommendation. This study indicates that the proposed approach is capable of leading crack strain fields of RC slabs to remaining life-span simulation of damaged RC for the case of low intensity and high cycle fatigue actions.

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In recent years, an interes in the corrosion monitoring technique of steel in marine concrete structures has been increased. Monitoring the reinforcement corrosion, it is crucial to be aware of corrosion threshold for damages or early repair and rehabilitation due to economical and safety aspects. A number of corrosion monitoring sensors have been proposed world-widely to predict the proper repair time of concrete structures. However, most of sensors introduced so far have some limitations to reach to the reliable status to evaluate corrosion continuously and accurately. A multi-functional compact sensor to monitor several corrosion factors has been proposed in this study, and the electrochemical and physical evaluation has been carried out to investigate rebar potential, corrosion rate, passivation state of rebar surface, and temperature of concrete. Five different environments, i.e. atmospheric, tap water, seawater, 15% seawater, and 15% seawater wet-dry cycle, have been applied, and a reasonable prediction of corrosion has been obtained in terms of non-destructive electrochemical point of view.

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