Flexural behavior and a new model for flexural design of concrete beams hybridly reinforced by continuous FRP bars and discrete steel fibers

Li, Chuanchuan; Zhu, Haitang; Niu, Guoqiang; Cheng, Shengzhao; Gu, Zhiqiang; Yang, Lin

doi:10.1016/j.istruc.2022.02.037

Cited by 12 publications

(7 citation statements)

References 33 publications

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“…Besides, the bridging effect of fibers helps to control the compression failure of fiber-reinforced concrete (FRC) beams, allowing the high strength of FRP bars to be effectively utilized [ 12 ]. Gao [ 39 ] and Li [ 40 ] suggested the maximum volume ratio of steel fiber (SF) to be 1.5% and 1.0% for concrete beams. In addition, studies by Mydin [ 41 ] found that the inclusion of SF at approximately 0.75–1.0% content in volume within a concrete mixture helped improve its flexural strength and ductility.…”

Section: Introductionmentioning

confidence: 99%

“…Some recent studies have concentrated on the flexural performance of BFRP-RC beams subjected to four-point bending static loads [ 12 , 20 , 29 , 30 , 36 , 40 ]. Ovitigala [ 30 ] found that all the tested beams had failed by the top concrete crushing.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the average bond-dependent coefficient value for BFRP-RC beams was found to be 0.70, which is significantly lower than the conservative value suggested by the ACI guidelines. Zhu [ 36 , 40 ] studied the flexural behavior of fiber-reinforced high-strength concrete beams reinforced with BFRP bars under four-point bending tests. The results show that a higher ρ f results in improved flexural performance, including higher flexural strength, post-cracking stiffness and ductility, and smaller crack width.…”

Section: Introductionmentioning

confidence: 99%

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Flexural Performance of Concrete Beams Reinforced with Continuous FRP Bars and Discrete Steel Fibers under Cyclic Loads

Zhu

Cheng

et al. 2022

Polymers

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This research investigated the flexural behavior of high-strength concrete beams reinforced with continuous basalt fiber-reinforced polymer (BFRP) bars and discrete steel fibers. Five concrete beams with the dimensions of 150 × 300 × 2100 mm3 were constructed and tested to failure under four-point bending cyclic loading. The specimens consisted of four BFRP-reinforced concrete beams with various reinforcement ratios (ρf), namely, 0.56%, 0.77%, 1.15%, and 1.65%, and one conventional steel-reinforced concrete beam for comparison purposes. The cracking behavior, failure modes, load-deflection behavior, residual deformation, and stiffness degradation of the beams were studied. Additionally, a deformation-based approach was used to analyze the deformability of the beams. The results show that an increase in the ρf effectively restrained the crack widths, deflections, and residual deformation while also enhancing the flexural bearing capacity of the beams. In comparison to the first displacement cycle, the bearing capacity dropped by 10% on average in the third cycle. The stiffness exhibited a fast to slow degradation trend until failure. The residual stiffnesses were higher in beams with a higher ρf. The over-reinforced beams had superior deformability than the under-reinforced beams, according to the deformability factors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flexural Performance of Concrete Beams Reinforced with Continuous FRP Bars and Discrete Steel Fibers under Cyclic Loads

Zhu

Cheng

et al. 2022

Polymers

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“…At the service stage, increasing the steel fiber volume ratio had a larger effect than at the final stage. The deflections and cracking response of the beam with a 2.0 % steel fiber volume ratio were like those of the beam with a 1.5 % steel fiber volume ratio (Li et al, 2022). The compressive, splitting, tensile, and flexural strengths of concrete decreased as the time between pouring two layers of concrete increased (Bekem Kara, 2021).…”

Section: Introductionmentioning

confidence: 74%

Flexural Behavior of Two-layers Reinforced Concrete Beams

Najm

2023

Polytechnic j.

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High-strength concrete is used to reduce the size of the beams in addition to enhancing the strength, this leads to overestimated cost in comparison with normal-strength concrete while using normal-strength concrete leads to the overestimated amount of concrete (layer size) of the beam section. For balancing the condition between the cost and size of beams, the benefit of both materials is used, by using beams in two layers, high-strength concrete in the compression zone (top layer), which is more beneficial for beam strength, and normal strength concrete in tension zone (bottom layer), which is no need using high strength concrete the in-tension zone. This study investigates the flexural and shear behavior of reinforced concrete beams consisting of two layers with different concrete strengths (grades), for beams with and without shear reinforcement (stirrups), considering the effect of shear-span ratio, layer thickness, layer compressive strength, and the overlap time casting of the two layers. The experimental program consists of a total of nineteen reinforced concrete beams of dimension (125 mm x 250 mm) with a total length of 1200 mm, the beams are reinforced with longitudinal reinforcement (4Ø12mm) and using (Ø8mm) bar as transverse reinforcement (stirrups). The experimental results show that the crack pattern of the two-layer reinforced concrete is closer to the crack of the control beam with one layer. Increasing the compressive strength of the concrete of the top layer, the ultimate failure load increased by (8.35%, 15.6%, and 18.85%), with respect to the (control beam) with the full depth of normal concrete. By increasing the high-strength layer thickness, the value of shear strength (Vc) and ultimate shear strength (Vu) increased linearly. The casting overlap time of up to (60 min) can be used for casting two-layered reinforced concrete beams, which is recommended, beyond this time the strength of the shear strength (Vc) and, ultimate shear strength (Vu) decreases. With increasing the shear span ratio (a/d) from (1 to 1.5 and 2) the ultimate load failure decreased by (33% and 50%). The shear strength capacity decreases with increasing stirrup spacing.

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“…Although the ultimate strength of over-reinforced beams was only slightly affected, the structural behavior of the beams was greatly enhanced by increasing the FRP reinforcement ratio [ 41 ]. The test findings demonstrate that adding more FRP reinforcements improves the flexural behavior of the structure, including its load-bearing capacity, postcracking stiffness, and deformation capability.…”

Section: Literature Reviewmentioning

confidence: 99%

Investigation of CFRP Reinforcement Ratio on the Flexural Capacity and Failure Mode of Plain Concrete Prisms

Qureshi

Saleem²,

Khurram³

et al. 2022

Materials

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The utilization of carbon-fiber-reinforced polymer (CFRP) composites as strengthening materials for structural components has become quite famous over the last couple of decades. The present experimental study was carried out to examine the effect of varied widths of externally bonded CFRP on the debonding strain of CFRP and the failure mode of plain concrete beams. Twelve plain concrete prims measuring 100 mm × 100 mm × 500 mm were cast and tested under identical loading conditions. The twelve specimens include two control prisms, i.e., without CFRP strips, and the remaining ten prisms were reinforced with CFRP strips with widths of 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm, respectively, i.e., two prisms in each group. Four-point loading flexural testing was carried out, and the resulting data are presented in the form of peak load vs. midpoint displacement, load vs. concrete strain, and load vs. CFRP strain. The peak load was directly recorded from the testing machine, while the midpoint deflection was recorded through the linear variable differential transducer (LVDT) installed at the midpoint. To measure the strain, two separate strain gauges were installed at the bottom of each concrete prism, i.e., one on the concrete surface and the other on the surface of the CFRP strip. The results of this study indicate that the debonding strain is a function of CFRP strip width and that the failure patterns of beams are significantly affected by the CFRP reinforcement ratio.

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Flexural behavior and a new model for flexural design of concrete beams hybridly reinforced by continuous FRP bars and discrete steel fibers

Cited by 12 publications

References 33 publications

Flexural Performance of Concrete Beams Reinforced with Continuous FRP Bars and Discrete Steel Fibers under Cyclic Loads

Flexural Performance of Concrete Beams Reinforced with Continuous FRP Bars and Discrete Steel Fibers under Cyclic Loads

Flexural Behavior of Two-layers Reinforced Concrete Beams

Investigation of CFRP Reinforcement Ratio on the Flexural Capacity and Failure Mode of Plain Concrete Prisms

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