Experimental Observation on the Effectiveness of Fiber Sheet Strip Stirrups in Concrete Beams

Steel-CFRP composite and their shear response as vertical stirrup in beams

“…The applied shear stresses in a cracked reinforced concrete member without shear reinforcement are resisted by various shear mechanisms such as shear stresses in un cracked concrete, interlocking action of the aggregate, dowel action of the longitudinal reinforcing bars, arch action, and residual tensile stresses transmitted directly across the cracks Lee et al (2010), McGregor and Wight (2008). Following both latter researches, experimental shear resistance listed in column number (4) were calculated by subtracting the shear strength of the NS beam from the corresponding shear strength of the beams reinforced with steel-CFRP composite stirrup.…”

“…The problem of reducing the capacity of FRP as a result to bend it, when using as stirrup, represents a big challenge. Lee et al (2010) mentioned that the conventional FRP rod stirrups have the following shortcomings: they are not flexible enough to bend to form a stirrup as required in the construction field due to several inherent material disadvantages of FRPs such as non-plastic behaviour and very low shear or transverse strength, a separate manufacturing process is needed for fabricating different sizes and shapes of FRP stirrups, and premature failure at a bent portion of FRP stirrups due to a stress concentration requires the use of FRP stirrups with excessive sectional area, leading to a partial loss of competitiveness in cost.…”

“…4R-04 (2004), El-Sayed et al (2007), CAN/CSA- S06-06 (2006). To solve the inherent problem of bend FRP when used as stirrups, Lee et al (2010) strengthened the bend points of fibre sheet strip stirrups by bonding additional overlaps of fibre sheet strip stirrups (FSS) at bend portion. Five auxiliary steel stirrups of diameter 6 mm two at the vicinity of each support and one at mid span were used to support the flexural reinforcement cages before applying the FSS stirrups, Fig.…”

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

“…The bent corner fracture is concerned with the stress concentration. As is shown in Figure 1, the bending fabric process makes the inner fiber kinked compared with the outer fibers (Lee et al, 2010). Therefore, the inner fibers tend to be less stressed as compared with those at the outer radius.…”

“…In order to improve the performance of FRP stirrups, Lee et al (2010) firstly proposed strip stirrups handmade by winding CFRP sheets strips around the longitudinal bars of reinforcement cages. The cross-section of strip stirrups was rectangular and closed.…”