Carbon Fiber-reinforced Polymer Straps Research Articles

Improving shear capacity of RC T-beams using CFRP composites subjected to cyclic load

Various methods are developed for strengthening reinforced concrete beams against shear. Nowadays, external bonding of various composite members to RC beams was very popular and successfully technique internationally. This study present test results on strengthening of shear deficient RC beams by external bonding of carbon fiber reinforced polymer (CFRP) straps. Six RC beams with a T section were tested under cyclic loading in the experimental program. Width of the CFRP straps, arrangements of straps along the shear span, and anchorage technique that were applied at the ends of straps was the main parameters that were investigated during experimental study. Inclined CFRP straps were bonded along the shear spans of shear deficient beams for strengthening against shear by using epoxy. Arrangements and width of the inclined CFRP straps were the main parameters that were changed among the specimens. The test results confirmed that all CFRP arrangements improved the strength and stiffness of the specimens significantly. The failure mode, and ductility of specimens were proved to differ according to the CFRP strap width and arrangement along the beam. Experimental results were compared with the analytical approaches that were suggested by ACI-440 Committee report.

External Prestressed Carbon Fiber-Reinforced Polymer Straps for Shear Enhancement of Concrete

The use of fiber-reinforced polymers (FRPs) for the strengthening and repair of existing concrete structures is a field with tremendous potential. The materials are very durable and, hence, ideally suited for use as external reinforcement. Although extensive work has been carried out investigating the use of FRPs for flexural strengthening, a fairly recent development is the use of these materials for the shear strength enhancement of concrete. The current system investigates the use of posttensioned, nonlaminated, carbon fiber-reinforced polymer (CFRP) straps as external shear reinforcement for concrete. Experiments were carried out on an unstrengthened control beam and beams strengthened with external CFRP straps. It was found that the ultimate load capacity of the strengthened beams was significantly higher than that of the control specimen. Existing design codes and analysis methods were found to underestimate the ultimate resistance of the control specimen and the strengthened beams. Nevertheless, the modified compression field theory provided insight into possible failure mechanisms and the influence of the strap prestress level on the structural behavior. It is concluded that the use of these novel stressed elements could represent a viable and durable means of strengthening existing concrete infrastructure.