Fatigue Performance Analysis of Damaged Steel Beams Strengthened with Prestressed Unbonded CFRP Plates

Abstract

A study was experimentally and numerically conducted to investigate the fatigue performance of notched steel beams strengthened with prestressed unbonded carbon-fiber-reinforced polymer (CFRP) plates. The experimental study included several large-scale edge-notched steel beams that were strengthened by unbonded CFRP plate with different prestress levels and then tested under cyclic fatigue load. The experimental results indicated that the proposed anchorage and prestressing system is feasible and reliable, and the prestress effect is significant not only for life extension but also in the stiffness decay reduction of the specimens. The highest prestressing level leads to over eightfold increase in the fatigue life of specimens. Furthermore, an analytical model was proposed to determine the effects of prestress level on the fatigue life of reinforced specimens based on a modified Paris’ law. Relative to the experimental results, the predicted results from the analytical model are satisfactory. Moreover, the regression analysis of the experimental results determined that the recommended values of parameter n and C in the modified Paris’ law were 3. and 2.72×1−12.