Shear strengthening of reinforced concrete beams with carbon fiber reinforced polymer (CFRP) and improved anchor details

Fifteen tests were conducted to evaluate the shear performance of beams with carbon fiber reinforced polymer (CFRP) laminates and CFRP anchors. The specimens consisted of 24-in. deep T-beams. The specimens were strengthened in shear with CFRP laminates that were anchored using several different CFRP end anchorage details. Load was applied to the reinforced concrete members at three different shear span-to-depth ratios. Observations of the behavior and data from the tests were used to evaluate the performance of the CFRP laminates and CFRP anchors. Overall, a 30-40% increase in shear strength was observed when anchored CFRP laminates were installed on members loaded at a shear span-to-depth ratio greater than two. The CFRP strengthening system performed well when properly detailed CFRP anchors were installed. Design recommendations regarding the installation of the CFRP anchors were developed. The CFRP anchorage detail developed in this study provided additional CFRP material in critical locations to reinforce the anchor and prevent premature failures from occurring due to anchor rupture. Theoretical calculations predicting the shear strength of the retrofitted concrete members were carried out and compared to the measured strengths of the members. Based on this analysis, a design equation was developed that produced conservative results for all of the specimens tested.