Shear behavior of concrete beams reinforced with closed-type winding glass fiber-reinforced polymer stirrups

Abstract

Conventional pultruded fiber-reinforced polymer (FRP) rod stirrups are susceptible to premature bent corner rupture and bond slip failure of overlapping legs. This research proposed a new type FRP shear reinforcement, closed-type winding GFRP (CW-GFRP) stirrups, featuring a fully closed rectangular cross-section. CW-GFRP stirrups completely avoided slip and significantly improved the strength of bent portion of stirrups. To investigate the feasibility of using CW-GFRP stirrups as shear reinforcement, shear test of 8 concrete beams reinforced with conventional pultruded stirrups and CW-GFRP stirrups was conducted. The beams were 300 mm deep and 150 mm wide, and their shear span ratio were 2.07. The effect of the material of stirrups, the spacing of stirrups, and the width of CW-GFRP stirrups were investigated. The test results showed that pultruded stirrups exhibited bond slip failure, in contrast, CW-GFRP stirrups reinforced beams prevented this failure and showed enhanced stiffness, narrower shear crack width and 1.09–1.12 times higher shear capacity. The splitting failure typical of CW-GFRP stirrups was reported, and a smaller stirrups width is expected to avoid splitting and generate greater strain at ultimate. It can be concluded that the new type of CW-GFRP stirrups is an optimized form of FRP shear reinforcement to supersede conventional pultruded stirrups. Strut-and-tie models based on ACI 318-19 and CSA S806-14 were used to predict the shear strength and produced a safe but relatively accurate prediction.

Long-term shear performance of concrete beam with carbon fiber-reinforced composite grid stirrups under sustained loadings and seawater immersion

“…Compared to that of the control specimen, the shear load capacity increased by 10.0%, 8.2% and 10.2% for the specimens after 90-, 180- and 360-days immersion, respectively. The increase in the shear load capacity may be attributed to the enhancement of the bond between the CFRP grid and the concrete, increasing the compressive strength of the concrete (Dong et al, 2018; Yuan et al, 2022). The shear load capacity after 180 days of immersion can be attributed to the degradation of the CFRP surface.…”

An Experimental and Numerical Analysis of the Flexural Performance of Lightweight Concrete Beams reinforced with GFRP Bars

“…The analysis of prior research indicates that there are few available experimental tests for the bending response of beams made of LWCBs reinforced with GFRP bars, particularly for LWC beams with a specific gravity half that of NC. Many of these researches [1][2][3][4][5][6][7][8][9][10][11][12] were concerned with the structural behavior and the mechanical characteristics affected by the type of Lightweight Aggregates (LWA) and the composition of the LWC blends as well as the kind and ratio of Fiber Reinforced Polymer (FRP) reinforcement. Authors in [1] experimentally tested lightweight and fibered lightweight concrete (LWC and LWCF) beams in terms of bending and ductility and compared the results with that of conventional concrete beams.…”