Investigation of fan type anchors for bonding fibrous polymer sheets to concrete

CFRP strips are widely used for repair/strengthening or capacity increase purposes nowadays. Sharp bending at the ends of the CFRP strips is frequently encountered at these applications. In this study, Reinforced Concrete (RC) beam specimens that were produceed with 10 MPa compression strength concrete were strengthened by using bonded CFRP strips with end anchorages to tension region. The parameters that were investigated with this study are the width of the strip, the number of applied fan anchorages and whether additional layer of CFRP patch is used or not at the strip ends. Specimens were strengthened with 100 mm wide CFRP strips with one or two anchorages at the ends. In addition CFRP patch with two and three anchorages at the ends were tested for investigating the effect of the patches. Specimens that were strengthened with three anchorages at the ends with patches were repeated with 60 and 80 mm wide CFRP strips. In the experimental elements with three anchors, the plates worked like a tension rod and were completely separated from the concrete. In the experimental study, the experimental element with three fan anchors and an additional layer at the end of the 80 mm wide plate was the most successful. In the test element, the CFRP sheet carried a load of 60% of its capacity. Although the plate width was reduced by 20% compared to the element with a plate width of 100 mm, the strength did not change, but the stress on the plate increased. In addition, the experimental element, in which the plate width was further reduced by making the plate width 60 mm, exhibited the same strength. However, the collapse did not occur in the desired form and only one of the three anchors collapsed. In the experiments, the 150 mm diameter fan anchors used at 50 mm intervals in concrete with a strength as low as 10 MPa did not collapse due to concrete.