The influence of FRP bars and reinforcement ratio on bending for FRP-reinforced concrete beams

2015 ◽  
Vol 19 (sup8) ◽  
pp. S8-251-S8-254
Author(s):  
L. Song ◽  
B. Li ◽  
D. Chen
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Frp Bars

scholarly journals Numerical Sensing of Plastic Hinge Regions in Concrete Beams with Hybrid (FRP and Steel) Bars

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3255 ◽  
Author(s):  
Fang Yuan ◽  
Mengcheng Chen
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Plastic Hinge ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Concrete Members ◽  
Steel Bars ◽  
Hybrid Reinforcement ◽  
Steel Hardening

Fibre-reinforced polymer (FRP)-reinforced concrete members exhibit low ductility due to the linear-elastic behaviour of FRP materials. Concrete members reinforced by hybrid FRP–steel bars can improve strength and ductility simultaneously. In this study, the plastic hinge problem of hybrid FRP–steel reinforced concrete beams was numerically assessed through finite element analysis (FEA). Firstly, a finite element model was proposed to validate the numerical method by comparing the simulation results with the test results. Then, three plastic hinge regions—the rebar yielding zone, concrete crushing zone, and curvature localisation zone—of the hybrid reinforced concrete beams were analysed in detail. Finally, the effects of the main parameters, including the beam aspect ratio, concrete grade, steel yield strength, steel reinforcement ratio, steel hardening modulus, and FRP elastic modulus on the lengths of the three plastic zones, were systematically evaluated through parametric studies. It is determined that the hybrid reinforcement ratio exerts a significant effect on the plastic hinge lengths. The larger the hybrid reinforcement ratio, the larger is the extent of the rebar yielding zone and curvature localisation zone. It is also determined that the beam aspect ratio, concrete compressive strength, and steel hardening ratio exert significant positive effects on the length of the rebar yielding zone.

scholarly journals Experimental analysis of steel fiber reinforced concrete beams in shear

2022 ◽  
Vol 15 (3) ◽  
Author(s):  
Aaron Kadima Lukanu Lwa Nzambi ◽  
Dênio Ramam Carvalho de Oliveira ◽  
Marcus Vinicius dos Santos Monteiro ◽  
Luiz Felipe Albuquerque da Silva
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Longitudinal Reinforcement ◽  
Fiber Addition

Abstract Some normative recommendations are conservative in relation to the shear strength of reinforced concrete beams, not directly considering the longitudinal reinforcement rate. An experimental program containing 8 beams of (100 x 250) mm2 and a length of 1,200 mm was carried out. The concrete compression strength was 20 MPa with and without 1.00% of steel fiber addition, without stirrups and varying the longitudinal reinforcement ratio. Comparisons between experimental failure loads and main design codes estimates were assessed. The results showed that the increase of the longitudinal reinforcement ratio from 0.87% to 2.14% in beams without steel fiber led to an improvement of 59% in shear strength caused by the dowel effect, while the corresponding improvement was of only 22% in fibered concrete beams. A maximum gain of 109% in shear strength was observed with the addition of 1% of steel fibers comparing beams with the same longitudinal reinforcement ratio (1.2%). A significant amount of shear strength was provided by the inclusion of the steel fibers and allowed controlling the propagation of cracks by the effect of stress transfer bridges, transforming the brittle shear mechanism into a ductile flexural one. From this, it is clear the shear benefit of the steel fiber addition when associated to the longitudinal reinforcement and optimal values for this relationship would improve results.

Effect of cracking localization on the structural ductility of normal strength and high strength reinforced concrete beams with steel fibers

2019 ◽  
Vol 10 (4) ◽  
pp. 457-469 ◽  
Author(s):  
Avraham N Dancygier ◽  
Yuri S Karinski
Keyword(s):  
Reinforced Concrete ◽  
Transition Point ◽  
Concrete Beams ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Flexural Ductility ◽  
Ductility Ratio ◽  
The Impact

This article presents a study of cracking localization in normal and high strength concrete beams that include steel fibers and the influence of this localization on their structural ductility. It is shown that for a given fiber type and content, as the reinforcement ratio ρ decreases, the cracking localization level increases. The effect of ρ on the level of cracking localization is more pronounced for low amounts of conventional reinforcement. This range of conventional reinforcement ratio is typical of slabs and especially for the commonly thicker protective slabs. Examination of the effect of the reinforcement ratio on the flexural ductility shows that there exists a transition point below which the ductility ratio decreases with  ρ. This transition point is well above the minimum reinforcement ratio, which is required in design codes for plain reinforced concrete elements. Empirical analysis of the relation between cracking localization and ductility ratio shows that up to the same transition point, as cracking localization increases, the flexural ductility decreases. Findings of this study show that the positive effect of adding fibers on enhancing the impact resistance of slabs and beams is conflicted by their negative influence on reducing the structural ductility for low reinforcement ratios, which are typical of protective slabs.

Does the shear strength of reinforced concrete beams and slabs depend upon the flexural reinforcement ratio or the reinforcement strain?

2013 ◽  
Vol 40 (11) ◽  
pp. 1068-1081 ◽  
Author(s):  
Mitra Noghreh Khaja ◽  
Edward G. Sherwood
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Shear Stresses ◽  
Shear Design ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
General Method

Beam tests are conducted to investigate the effect of the reinforcement ratio, ρ, and the shear span to depth ratio, a/d, on the shear strength of reinforced concrete beams and slabs without stirrups. The a/d ratio is shown to have a very significant effect on shear strength at both low values of a/d (where failure is governed by strut-and-tie mechanisms) and large values of a/d (where failure is governed by breakdown in beam action). Increases in ρ associated with increases in a/d such that the strain, or M/ρVd ratio, is kept constant will result in constant failure shear stresses. Shear design methods that do not account for a/d (e.g., ACI Committee 440) cannot predict the observed experimental behaviour, whereas the general method of the CSA A23.3 code can. Using the ACI 440 equation for Vc may reduce the economic competitiveness of fibre-reinforced polymer reinforcement versus steel reinforcement.

Analysis of Bending Stiffness of Reinforced Concrete Beams Strengthened with Carbon Fiber Sheet

2012 ◽  
Vol 204-208 ◽  
pp. 2887-2890
Author(s):  
Yan Han ◽  
Hong Bo Liu ◽  
Tao Guo
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Concrete Beams ◽  
Bending Stiffness ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Fiber Layer ◽  
Fiber Sheet ◽  
Carbon Fiber Sheet

The stiffness of reinforced concrete simple beams strengthened with carbon fiber sheets is studied in this paper. The calculation formulas of it are discussed, for steel yielding and not yielding. The stiffness increases with the number of carbon fiber layer or reinforcement ratio increases.

scholarly journals Shear Behavior of Fiber Reinforced Concrete Beams with Basalt FRP Reinforcing Bars and Glass FRP Stirrups

2020 ◽  
Author(s):  
Abathar AL-Hamrani ◽  
Wael Alnahhal
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fibers ◽  
Glass Fibers ◽  
Construction Materials ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced ◽  
Reinforcing Bars ◽  
Frp Bars

The State of Qatar suffers from a harsh environment in the form of high temperature that prevails almost all year round in addition to severe humidity and coastal conditions. This exposure leads to the rapid deterioration and the reduction of the life span of reinforced concrete (RC) infrastructure. The full functionality and safe use of the infrastructure in such environments can only be maintained by holistic approaches including the use of advanced materials for new construction.With the developments in materials science, the advanced composites, especially fiber reinforced polymer (FRP) materials are becoming viable alternatives to the traditional construction materials. Having superior durability against corrosion, versatility for easy in-situ applications and enhanced weight-to-strength ratios compared to their counterpart conventional materials, FRPs are promising to be the future of construction materials. More recently, FRP composites made of basalt FRP (BFRP) have been introduced as an alternative to traditional steel reinforcement at a price comparable to glass fibers of about $2.5–5.0 per kg, which is significantly lower than carbon fibers. BFRP bars are characterized by their corrosion resistance, greater strain at failure than carbon fibers, and better chemical resistant than glass fibers, particularly in a strongly alkaline environment. Knowing that FRP bars are anisotropic materials with weaker strength in the transverse direction compared with the longitudinal direction, and having a relatively low modulus of elasticity compared with steel reinforcement, it is important to investigate the concrete contribution to shear strength for beams reinforced with BFRP bars. In addition, due to the elastic performance of the FRP reinforcing bars compared with steel bars, FRP bars fail in a brittle manner. Moreover, concrete itself is a brittle material. Previous investigations have shown that using discrete fibers in concrete increases its ductility due to the large compressive strains exhibited at failure. Therefore, basalt macro-fibers is proposed in this study. A total of 14 concrete beam specimens were tested under four point loading until failure. The parameters investigated included the reinforcement ratio (2rb, 3.1rb, and 4.53rb, where rb is the balanced reinforcement ratio), the span to depth ratio (a/d=2.5, and a/d=3.3), the spacing between stirrups (S1=170mm, and S2=250mm) and the basalt fiber volume fraction (0%, 0.75% and 1.5%). Test results clearly showed that both BFRP bars and basalt macro-fibers can be used as sustainable and eco-friendly alternative materials in Concrete Structures in Qatar.

scholarly journals Limiting Reinforcement Ratios for Hybrid GFRP/Steel Reinforced Concrete Beams

2021 ◽  
Vol 11 (1) ◽  
pp. 01-11
Author(s):  
Duy Phan Nguyen ◽  
Viet Quoc Dang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Equilibrium Equations ◽  
Steel Reinforced Concrete ◽  
Glass Fiber Reinforced ◽  
Load Carrying

In this work, a theoretical approach is proposed for estimating the minimum and maximum reinforcement ratios for hybrid glass fiber reinforced polymer (GFRP)/steel-reinforced concrete beams to prevent sudden and brittle failure as well as the compression failure of concrete before the tension failure of reinforcements. Equilibrium equations were used to develop a method for determining the minimum hybrid GFRP/steel reinforcement ratio. A method for determining the maximum hybrid GFRP/steel reinforcement ratio was also developed based on the equilibrium of forces of the balanced failure mode. For estimating the load-carrying capacity of concrete beams reinforced with hybrid GFRP/steel, less than the minimum and more than the maximum reinforcement ratio is recommended. Comparisons between the proposed expressions, experimental data, and available test results in the literature shows good agreement between the theoretical and experimental data, with a maximum discrepancy of 7%.

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