Fatigue behavior of corroded prestressed concrete beams

• Fatigue tests were conducted on corroded prestressed concrete beams.
• The 3D geometric models of corroded wires or rebars were obtained.
• Fatigue failure mechanism of corroded prestressed concrete beams was revealed.
• Longitudinal variation of the cross-sectional area had a significant influence on fatigue behavior of corroded beams.

This paper presents the results of an experimental study on the fatigue behavior of pretensioned partially prestressed concrete beams with corroded prestressing wires or rebars. A three-dimensional laser scanning technique was employed to obtain the geometric models of corroded prestressing wires or rebars. It was observed that fatigue cracks initiated and propagated rapidly around corrosion pits under cyclic loading. The cyclic loading led to fatigue fracturing of the prestressing wires (rebars) at the minimum cross-section where the corrosion pits had formed. With the increased corrosion of the prestressing wires, the sooner fracture of the first wire and the shorter interval between the failures of the two wires in the test beam were found, resulting in a shorter fatigue life of the beam. A higher partially prestressed ratio or load range brought a larger stress level, stress range, and thus a shorter fatigue life of corroded beams. Compared with the uncorroded beam, it was also found that the corroded beams exhibited a faster stiffness degradation and development of deflections and crack widths under cyclic loading.