Effect of U-shaped anchorages on concrete cover separation in carbon fiber-reinforced polymer-strengthened beams with notches at the sheet end

摘要

Anchorage systems have been proven to efficiently prevent or postpone debonding of reinforced concrete structures strengthened in flexure with fiber-reinforced polymer (FRP) laminate or sheet. Although extensive studies on the effect of anchorage systems on intermediate crack debonding and end debonding of strengthened members have been performed, the effect of U-shaped anchorages on commonly faced concrete cover separation remains unclear, and a corresponding design proposal has not been completed, which limits the practical use of anchorage systems for strengthening. In this study, carbon fiber-reinforced polymer (CFRP)-strengthened beams with notches at the sheet end and CFRP U-shaped anchorages of various widths and heights were specially designed to investigate the effects of anchorages on strength of concrete cover separation. The height of the U-shaped anchorage was proved more important than its width to improve concrete cover separation strength, and the related mechanism was discussed. Furthermore, an analytical model was developed to predict the initial and full separation load of concrete cover with U-shaped anchorages. The reliability and accuracy of the proposed analytical procedure were verified against the test results.