FATIGUE RESPONSE OF CONCRETE DECKS REINFORCED WITH FRP REBARS

The fatigue response of concrete decks reinforced with fiber-reinforced plastic (FRP) bars is critical to the long-term endurance of this type of innovative structure. To evaluate the degradation of FRP reinforced bridge decks, fatigue tests were conducted on four concrete deck steel stringers. An initial stress range of 2.27 MPa (0.33 ksi) (tension) in the main FRP reinforcement, 3.1 MPa (0.45 ksi) (compressive) in the concrete deck top, and 24.8 MPa (3.6 ksi) (tension) at the bottom flange of a steel stringer was applied for all specimens. The stringer stiffness, composite versus noncomposite casting, and transverse posttensioning using high-strength Dywidag steel rods were varied during this research. The fatigue test results showed no loss of bond between FRP rebars and concrete in any of the test specimens. The major crack patterns were in the direction parallel to the stringers, i.e., flexural cracks in the concrete deck spanning the steel stringers. Effective central deck deflections could be set as a measure of global deck degradation during fatigue, and this rate of degradation in decks reinforced with FRP rebars was found comparable to decks reinforced with steel rebars.