Pseudo-Cracking Approach to Fatigue life Assessment of RC Bridge Decks in Service

Chikako Fujiyama, Xue Juan Tang, Koichi Maekawa and Xue Hui An

Journal of Advanced Concrete Technology, 11, 7-21, 2013

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.

The study provides a useful and practical approach to assess the remaining fatigue life of RC bridge decks without the need for loading history.  It also verifies the damage grade system defined in the JSCE maintenance code.
(Prof. Kiang Hwee Tan )
A highly sophisticated and new approach is described in this paper.
It does not follow the mainstream but has developed a new and original
approach. A basis for further promising work was elaborated.
(Prof. Folker H. Wittmann)