Análise experimental de vigas de concreto armado reforçadas à força cortante com compósitos de fibra de juta, carbono e vidro utilizando a técnica EBR

Abstract

The application of FRP (Fiber Reinforced Polymer) with the EBR (Externally Bonded Reinforcement) technique for repairing and reinforcing structures stands out due to the low density of the material and ease of application. In this case, the use of synthetic fibers is common, however, these fibers are considered inaccessible and harmful to the environment. This disadvantages raised studies on the replacement of synthetic fibers by natural fibers. Therefore, this work consists of the experimental analysis of the performance of composites of jute fibers as shear reinforcement. With that aim, seven reinforced concrete beams reinforced with FRP's were molded using the EBR technique, they were dimensioned with greater flexural strength in relation to the shear force and with transverse reinforcement positioned only in a section of the span, to induce shear failure in the region without stirrups. The beams are 2 meters long and have a cross section of (15x20) cm. One beam was not reinforced, to be used as a reference, one beam was reinforced with one layer of FRP with carbon fiber, one beam with two layers of FRP with glass fiber, two with hybrid FRP of layers of glass and jute fiber with three and four layers, and finally two beams with jute fiber FRP with two and three layers. The reinforcements were applied in strips along the length of the shear span of the elements, perpendicular to the axis of the beams, U-shaped. It was observed that the reinforcement with two layers of jute fiber presented a 48% increase in shear force of the beam in relation to the reference beam, this result was similar to that observed in the beam reinforced with one layer of carbon fiber. Other positive behaviors were observed in the other reinforced beams, such as cracking control, increase in maximum shear force and containment of vertical displacement in relation to the reference beam. The experimental results were compared to theoretical results calculated according to ABNT NBR 6118 (2004), ACI 318 (2014), Eurocode 2 (2004), ACI 440.2R (2017) and fib 90 (2019). After analysis, the initial results of this research demonstrate the viability for other in-depth studies on the use of jute fibers in shear reinforcement of reinforced concrete beams.