Flexural performance of RC beams externally strengthened with a single-layer of basalt fiber reinforced polymer sheets

Abstract

Basalt Fiber Reinforced Polymer (BFRP) is an environment friendly strengthening material that can be used in several engineering applications. In this research, an experimental program was directed to investigate the BFRP strengthening adequacy of reinforced concrete beams. Eight simple-span beams were tested under the four-point bending test and were all made from the same concrete mixture. One layer of BFRP was applied on the soffit of B1, while this layer was wrapped partially along the sides of beams B2, B3, and B4 with vertical side extensions of 25, 75, and 105 mm, respectively, to evaluate the effect of vertical extension of the bottom BFRP layer on the flexural behavior of the strengthened beams. The beams B5 and B6 were strengthened with three BFRP U-strips along the flexural span without and with a bottom layer of BFRP sheet, respectively. On the other hand, the bottom and side surfaces of B7 were fully wrapped with a layer of BFRP, while B0 was kept without strengthening as a reference beam. The test results showed that strengthening with BFRP can noticeably improve the beam load capacity at cracking, yield, and ultimate stages. The ductility of strengthened beams was less than B0 by up to 33% for partial side strengthening and 45% for full side strengthening, while the toughness of all strengthened beams was higher than that of reference beam by 8–78%. The results also showed that increasing the vertical side extension of the bottom BFRP layer leads to significant load capacity increase.

Effect of BFRP Sheets on Strengthening Deep Beams with Openings

“…vn=fce*sinθs*bw*ws (12) where fce = 0.85βs fc , ws = min [(wt cosθs + wb sinθs), (hc cosθs + wb sinθs )] βs for bottle-shaped struts with reinforcement satisfying Section A. 3…”

“…so, we choose this fiber trying to solve the problems which happen due to existing of openings in deep beams such as the reduction in strength of the beam, more cracks, and deflection in addition to that, openings disrupt the normal stresses flow, resulting in concentration of stress at the openings' sides and early cracking of concrete by strengthening these openings with basalt fiber reinforced polymer sheets, and also trying to solve the problem of pollution due to carbon fiber. The last searches of BFRP were about its behavior individually, as a ratio of concrete mix, BFRP bars, and as a strengthening material (3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Hannibal Ólafsson et al (3) made a review on basalt fiber, the different methods of production, and tests done on it as a strengthening material for R.C.…”

“…Surya Sunder S et al (11) made an experimental program to study the influence of strengthening circular openings in R.C beams at the shear zone with one and two openings using the BFRP wrapping system around and inside the openings. Kadhim et al (12) studied the Flexural attitude of RC beams strengthened with one layer of BFRP sheets. In this paper, 2 layers of BFRP sheets are used to strengthen deep beams with openings, the properties of BFRP sheets (tensile strength, ultimate strain, and elongation at failure have been studied by testing 3 specimens of sheets roughed with sand to simulate the contact of basalt and concrete also, its behavior when using it in strengthening deep beams have been studied where no searches have been used BFRP in strengthening deep beams with openings.…”

Influence of Basalt and Geo-Textile Fiber Wrapping on Compressive and Flexural Strengths of HDPE-filled Reinforced Concrete

“…A catastrophic failure in plain concrete was observed in the loading direction and is depicted in Figure 5(a). Enhancing the strength of concrete can be achieved by the wrapping technique, but reduced ductility was observed with this technique (15,18,19,28) . This is due to brittle failure of concrete and hence transfer of load to FRP wrapped jacket.…”

“…Wrapping of Fiber Reinforced Polymer [FRP] enhances the load-carrying capacity and deflection (14) . The effect of BFRP wrapping on the bottom and vertical side of the beam on flexural performance was studied by Sara Kadhim et.al (15) . The author reported that the ductility of BFRP-wrapped beams is less than the reference beam.…”