Remaining fatigue life assessment of in-service bridge deck considering crack width and moisture conditions

Abstract

In the service life-span of existing RC bridge decks, the extent of fatigue damage significantly influences the remaining fatigue life (N_f,r) and subsequent fatigue performance of damaged RC bridge decks. The primary manifestation of fatigue damage is crack width. In this study, based on the conditions of real-world bridges under dry and wet condition, a multi-scale and multi-physical analysis system considering water-crack interaction and pseudo-cracking method are employed. These methods systematically calculated the subsequent fatigue development and remaining fatigue lives of damaged RC bridge decks with different crack widths in identical distribution under wheel-type moving loads (WTMLs) with varying weights. The results show that crack width has a great impact on remaining fatigue life, with larger crack widths leading to higher sensitivity of remaining fatigue life and initial deflection to load weights. When the crack scale factor (crack width multiplier) η is between 1 and 5, the degradation of remaining fatigue life of RC bridge decks under dry condition becomes more pronounced with increasing crack widths. Both dynamic response of mid-span strain to WTMLs and remaining fatigue life exhibit greater sensitivity to crack width under dry condition than under wet condition. Finally, based on dual-parameter Weibull distribution model, a relationship is established between remaining fatigue life of damaged RC bridge decks under different loads and crack widths. The determination coefficients R² for the relationships established under the four conditions all exceeded 0.965, indicating a high accuracy of fit.