Experimental Study on Fatigue Behavior of Cracked Rectangular Hollow-Section Steel Beams Repaired with Prestressed CFRP Plates

The bending fatigue test results on cracked rectangular hollow section (RHS) steel beams repaired with prestressed carbon fiber-reinforced polymer (CFRP) plates are presented. The steel beams were artificially cut on the bottom of the midspan at various depths (3, 10, and 30mm) before the test. Six prestressed CFRP plate-repaired steel beams were prepared with two prestressing levels. Six non-prestressed CFRP plate-repaired steel beams were repaired with two types of CFRP. Three more specimens were arranged as a control group. All specimens were subjected to fatigue loading. Fatigue crack propagation, failure modes, deflections, and strains were recorded and analyzed. The objective of this investigation was to determine the effect of the prestressing level in CFRP plates, repairing the material's modulus and initial crack depth on the fatigue behavior of RHS beams. The test results indicated that a higher modulus material or a larger prestressing level could improve the fatigue performance. Repaired beams with prestressed CFRP plates exhibited a slight stiffness degradation, whereas repaired beams with non-prestressed CFRP plates exhibited significant stiffness degradation during the fatigue loading.