An Experimental and Numerical Investigation on the Bending Behavior of Fiber Reinforced Concrete Beams (original) (raw)
Related papers
2020
This study mainly investigates the flexural performance of reinforced concrete beam (RCC) using polypropylene and steel fibers separately as well as combination of both fibers. Prior to specimen preparation, the physical and mechanical properties of polypropylene and steel fibers were determined. Moreover, the physical properties of binding material, coarse aggregates and fine aggregates were determined. In this research, four categories of beam specimens (4 ́ x 6 ́ ́ x 6 ́ ́size and selected suitable mixing ratio of 1:2:4) were constructed encompassing normal RCC beam (control); addition of 1.5% steel fiber; 2% polypropylene fiber; and combination of 0.5% steel fiber and 1.5% polypropylene fiber in volume of concrete. Experimental results showed that there is considerable increase of flexural strength due to addition of 1.5% steel fiber and 2% polypropylene fiber in concrete. However, the addition of both fibers (hybrid fiber) in combined not only increase the flexural performance ...
Experimental Study and Modelling on the Structural Response of Fiber Reinforced Concrete Beams
Applied Sciences
In many structural applications, concretes reinforced with short metal or synthetic fibers (fiber-reinforced concrete (FRC)) have a number of advantages over traditional concretes reinforced with steel rebars reinforcement, such as easier and more economical production, wear resistance, impact resistance, integrity, etc. In the present study, several concrete mixes were developed and prismatic FRC specimens were fabricated. Their structural behaviors were studied using bending tests until prisms were fractured. Two types of fibers, namely, steel and polypropylene (PP) and three different concrete matrixes were investigated, testing in total 12 FRC prismatic specimens. Every group of FRC had the same concrete matrix, but different internal fiber architecture. All specimens were tested by Four-Point Bending (4PBT). The analysis was carried out with a goal to determine the workability and flexural tensile strength of all FRC groups, comparing these parameters with fracture modelling re...
Load-deflection Characteristics of Steel, Polypropylene and Hybrid Fiber Reinforced Concrete Beams
Concrete is the most widely used construction material because of its specialty of being cast into ductility and energy absorption capacity. Fiber reinforced concrete possesses high flexural and tensile strength, improved ductility, and high energy absorption over the conventional concrete in sustaining dynamic loads. The aim of this paper is to compare the properties of concrete beams in which three types of fibers are added individually. Steel fibers, polypropylene fibers and hybrid fibers were added to concrete in the volumetric ratio of four percentages in the preparation of four beam specimens. The fourth specimen had no fibers and acted as a control specimen. The dimensions of the beam specimens were 150 mm × 150 mm × 700 mm. The reinforced concrete beams of M30 grade concrete were prepared for casting and testing. Various parameters such as load carrying capacity, stiffness degradation, ductility characteristics and energy absorption capacity of FRC beams were compared with that of RC beams. The companion specimens were cast and tested to study strength properties and then the results were compared. All the beams were tested under three point bending under Universal Testing Machine (UTM). The results were evaluated with respect to modulus of elasticity, first crack load, ultimate load, and ultimate deflection. The test result shows that use of hybrid fiber improves the flexural performance of the reinforced concrete beams. The flexural behavior and stiffness of the tested beams were calculated, and compared with respect to their load carrying capacities. Comparison was also made with theoretical calculations in order to determine the load-deflection curves of the tested beams. Results of the experimental programme were compared with theoretical predictions. Based on the results of the experimental programme, it can be concluded that the addition of steel, polypropylene and hybrid fibers by 4% by weight of cement (but 2.14 % by volume of cement) had the best effect on the stiffness and energy absorption capacity of the beams.
The Effects of Fibers on Concrete Beams Flexure and Shear Capacities
2022
An experiment program was created to determine the effectiveness of fibers as reinforcement in concrete beams. Premixed concrete was used instead of creating a new mix design. Steel fibers and synthetic macrofibers were used in this experiment. Three tests were conducted on various elements using three different fiber volume fractions of 0.736%, 1.105%, and 1.473%. Specifically, large scale beams with longitudinal reinforcement were tested to determine shear and moment capacities; small beams without longitudinal reinforcement were tested to find the modulus of rupture; and concrete cylinders were tested to determine the compressive strength. From the cylinder test, it was shown that as the volume fraction increased, the compressive strength decreased. Also, the steel fibers increased the compressive strength significantly. On the other hand, the synthetic macrofibers only increased it 1.04% for a volume fraction of 0.736%. In fact, after the volume fraction increased beyond 0.736% for the synthetic macrofibers, the compressive strength value started to decrease. The small beams test showed that the steel fiber beams had a higher residual capacity than the synthetic macrofiber beams. It was also shown that a fiber volume fraction of 1.105% resulted in the highest modulus of rupture out of the three volume fractions. This fiber volume fraction also showed a higher load capacity than the other volume fractions. It was also shown that the crack location impacted the modulus of rupture. The test on large scale beams showed that as the fiber volume fraction increased, the moment and shear capacities increased as well. It was also shown that steel fiber beams had higher shear and moment capacities as well as maximum load capacity compared to synthetic macrofiber beams.
Procedia Engineering, 2015
The research was conducted to determine the bending capacity of high-strength reinforced concrete beams with the addition of three environmentally friendly synthetic fibers i.e., polypropylene fiber, tie wire fiber, and used rubber tires fiber. Four beams with a dimension of 15 x 30 x 220 cm were tested, including a beam for specimen without fiber as comparison. Specimens were designed to experience bending failure. Yield point of steel (fy) used for flexural and shear reinforcement was 407.43 MPa. The diameter of flexural tensile reinforcement was 15.8 mm, 11.9 mm for the compressive reinforcement, as well as 11.9 mm for the shear reinforcement. Concrete proportion incorporated 8% silica fume and 1.5% polycarboxylate ethers based superplasticizer ViscoCrete 10 from the cement weight. The maximum diameter of split was 15.9 mm, having 550 kg/m3 cement content and w/cratio 0.30. The target compressive strength was 70 MPa for cylinder 15/30 cm. The results showed that all beams experienced flexural failure as planned. Addition of fibers enhanced the bending behavior significantly, especially in flexural capacity, deflection and ductility. In comparison with high-strength reinforced concrete beam without fibers, the beam with polypropylene fiber had the increase of flexural strength of 115.24%, deflection of 306.56% and ductility of 298.9%; with tie wire fibers resulted in the increase of flexural strength of 117.39%, deflection of 160.52% and ductility of 148.0%; as well as with used rubber tires fiber produced the enhance of flexural strength of 112.13%, deflection of 184.56% and ductility of 178.3%. It can be concluded that the use of such environmentally friendly synthetic fibers can reduce the brittleness of high strength concrete, in which polypropylene fiber had delivered the best value and can be used very effectively than the other two types of fibers.
Behavior of post-tensioned fiber concrete beams
HBRC Journal, 2013
This paper presents an experimental and analytical study on the behavior of post-tensioned concrete beams with variable discontinuous fibers' content. Eleven half scale T-shaped post-tensioned simple beams were cast and tested in four points bending under the effect of a repeated load using a displacement control system up to failure. The test parameters were the fibers' type (steel and polypropylene) and content, as well as the prestressing ratio (partially or fully). Key test results showed considerable enhancement in the crack distribution, crack width and spacing, concrete tensile strength and flexural stiffness in all beams with steel fibrous concrete. The latter aspects were directly proportional to the steel fibers' contents. On the other hand, beams containing polypropylene fibers demonstrated a slight decrease in the flexural strength and a slight increase in flexural stiffness. In addition, the tensile steel strains decreased in all fibrous concrete beams, with lowest values in steel fibrous concrete specimens when compared to those of the polypropylene fibers. Furthermore, fibrous concrete beams also demonstrated enhanced ductility and energy absorption, which reached the highest values for steel fibrous concrete specimens. Generally, it can be concluded that steel fibers proved to have higher structural efficiency than polypropylene fibers, when used in the tested specimens.
Structural Concrete, 2020
The use of fibers in reinforced concrete (RC) beams mainly improves both the bearing capacity and the cracking control. In this way, positive effects on the service life of RC structures can be expected. In this paper, the fiber influence on the flexural behavior of RC beams with different longitudinal reinforcement ratios (0.5% ≤ ρ s ≤ 1.2%) is analyzed by testing small-scale RC beams. Concretes incorporating 0, 25 and 50 kg/m 3 of steel, 6 and 12 kg/m 3 of glass macrofibers, and 5 and 10 kg/m 3 of polymer macrofibers were studied. Crack and deflection control, as well as bearing capacity and crack localization were evaluated for a broad range of fiber-reinforced concrete (FRC) toughness. It is verified that fibers, in the longitudinal reinforcement ratio considered, improve the bending behavior at serviceability limit state (SLS) and ultimate limit state (ULS) of RC beams, without limiting the structure ductility. It was also confirmed the philosophy of the fib Model Code 2010, such that FRC can be considered as a composite material where performance parameters govern its mechanical behavior. Finally, the several data available allowed to deeply analyze fib Model Code 2010 formulations (mean crack spacing and flexural bearing capacity) and to propose modifications where needed.
Shear Behavior of Fiber-Reinforced Concrete Beams: An Experimental Study
International Journal of GEOMATE, 2021
Eight steel fiber-reinforced normal strength concrete beams (200 mm wide, 250 mm deep and 1500 mm long) were tested in bending under two concentrated loads, without and with stirrups. The concrete beams were designed to have marked shear behavior. Three types of steel fibers (SFs), straight, hooked and corrugated, were investigated as a possible replacement for standard transverse reinforcement. The fiber volume content, the aspect ratio of fibers, and the existence of stirrups were the major testing parameters in this regard. Four fiber volume proportions (R f of 0%, 0.5%, 1.0% and 1.5%) and three aspect ratios (l/d of 50, 55 and 60) were utilized. According to the experimental data, the shear behavior of steel fiber-reinforced normal strength concrete beams (SFRCBs) without stirrups was similar, if not superior, to that of normal strength concrete beams (RCBs) with stirrup reinforcement. The SFRCBs displayed extremely thin diagonal cracks and higher shear strengths, especially for fiber fractions of 1% and 1.5%. The experimental results were compared to major universal codes and existing models from the literature. The major codes undervalue the concrete contribution to shear strength while exaggerating the contribution of the stirrups. Furthermore, some of the existing models overestimate the fibers' contribution to the shear strength, while others underestimate it when compared to the present experimental findings.
Hybrid fiber use on flexural behavior of ultra high performance fiber reinforced concrete beams
Composite Structures, 2019
In this study, the flexural behavior of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) beams produced in mono and hybrid forms were investigated experimentally and numerically. Twelve doubly reinforced concrete beams were casted with four different reinforcement ratios representing low to excessive levels. The beams were produced in three groups to study the effects of mono and hybrid steel fiber usages. The first group beams of four are non-fiber beams while the second group contains only short-straight fiber of 13 mm. The last group is composed of hybrid form where the short-straight fiber of 13 mm and the long-hooked fiber of 60 mm were blended together. The beams were subjected to four-point loading, and the parameters of deflection and curvature ductilities, flexural stiffness, flexural moment capacity, cracking behavior and compressive strain were discussed. The test results indicated that the UHPFRC beams with high reinforcement ratios above the limits in current design codes provide remarkable benefits through the fibers' contribution. It can be deduced that the hybrid fiber usage showed better flexural performance, in general, comparing to the mono form. In addition, two numerical approaches were proposed to predict nominal moment capacity of the UHPFRC beams in the mono or hybrid form.