Fatigue life prediction for prestressed concrete beams under corrosion deterioration process
Xiaochao Su, Yafei Ma, Lei Wang, Zhongzhao Guo, Jianren Zhang
Abstract
The coupled effect of corrosion and fatigue on performance degradation of prestressed concrete (PC) bridges is a dynamic process. This paper proposed a novel framework for the fatigue life prediction of corroded PC beams, where the chloride ingress process, pitting corrosion , cross-sectional area reduction of steel, pretension force loss, and fatigue damage accumulation of materials were considered. A dynamic residual cross-sectional area-based method was developed to estimate fatigue damage accumulation of materials, and competition between concrete failure criterion and Miner’s rule of cumulative damage theory of strand was included. Following this, the fatigue damage of naturally corroded PC beams was discussed, and an experimental study on the fatigue behavior of pre-corroded PC beams was conducted to validate the proposed model. The prediction results agreed well with the experimental observations. The results showed that the effects of load amplitude and vehicle load frequency on the prediction results were clarified. The deterioration of corroded PC beams is more sensitive to load amplitude than load frequency. With the corrosion rate of strand increasing to 3%, the failure mode of pre-corroded PC beams changes from the brittle fracture of steel bars to the brittle fracture of strands. Fatigue failure is caused by the sudden brittle fracture of longitudinal steel bar for naturally corroded beam. The proposed method provides a satisfactory result for evaluating the damage accumulation of PC beams with corroded strands or steel bar.