An Overview of Using Steel Fibers in Reinforced Concrete Structural Elements to Improve Shear Reinforcement (original) (raw)
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Influence of Steel Fiber on the Shear Strength of a Concrete Beam
Civil Engineering Journal, 2018
The shear failure in a concrete beam is a brittle type of failure. The addition of steel fibers in a plain concrete mix helps to bridge and restrict the cracks formed in the brittle concrete under applied loads, and enhances the ductility of the concrete. In this research an attempt was made to investigate the behavior and the ultimate shear strength of hooked end steel fiber reinforced concrete beams without traditional shear reinforcement. Four simply-supported reinforced concrete beams with a shear span-to-depth ratio of about 3.0 were tested under two-point loading up to failure. Steel fibers volumetric fractions that used were 0.0, 0.5, 0.75 and 1.0%. Test results indicated that using 1.0% volume fraction of hooked steel fiber led to exclude shear failure and enhanced the use of steel fibers as shear reinforcement in concrete beams. The results also showed that a concrete beam with hooked steel fiber provided higher post-flexural-cracking stiffness, an increase in the shear capacity and energy absorption and an increase in the maximum concrete and steel reinforcement strains.
Influence of Fiber Content on Shear Capacity of Steel Fiber Reinforced Concrete Beams
2019
For shear-critical structural elements where the use of stirrups is not desirable, such as slabs or beams with reinforcement congestion, steel fibers can be used as shear reinforcement. The contribution of the steel fibers to the shear capacity lies in the action of the steel fibers bridging the shear crack, which increases the shear capacity and prevents a brittle failure mode. This study evaluates the effect of the amount of fibers in a concrete mix on the shear capacity of steel fiber reinforced concrete beams with mild steel tension reinforcement and without stirrups. For this purpose, twelve beams were tested. Five different fiber volume fractions were studied: 0.0%, 0.3%, 0.6%, 0.9%, and 1.2%. For each different steel fiber concrete mix, the concrete compressive strength was determined on cylinders and the tensile strength was determined in a flexural test on beam specimens. Additionally, the influence of fibers on the shear capacity is analyzed based on results reported in th...
An Experimental Study On Shear Behavior Of Steel Fiber Reinforced Concrete Beam
2015
The present study investigate the influence of Steel Fiber Reinforcement on the mechanical behavior of reinforced concrete beams in shear.The major test variables are the aspect ratio of steel fiber, shear reinforcement, shear span(a) to depth ratio(d).The test result show that the first crack shear strength increases as fiber is added and also ultimate shear strength increases and change the mode of failure. It is concluded that fiber reinforcement can reduce the amount of shear stirrups required and that the combination of fibers and stirrups meet the strength and ductility requirements.
Behaviour of reinforced concrete slabs with steel fibers
This paper investigates the potential effect of steel fiber added into reinforced concrete slabs. Four-point bending test is conducted on six slabs to investigate the structural behaviour of the slabs by considering two different parameters; (i) thickness of slab (ii) volume fraction of steel fiber. The experimental work consists of six slabs, in which three slabs are designed in accordance to Eurocode 2 to fulfil shear capacity characteristic, whereas, the other three slabs are designed with 17% less thickness, intended to fail in shear. Both series of slabs are added with steel fiber with a volume fraction of Vf = 0%, Vf = 1% and Vf = 2% in order to study the effect and potential of fiber to compensate the loss in shear capacity. The slab with Vf = 0% steel fiber and no reduction in thickness is taken as the control slab. The experimental result suggests promising improvement of the load carrying capacity (up to 32%) and ductility (up to 87%) as well as delayed in crack propagation for the slabs with Vf = 2%. In addition, it is observed that addition of fibers compensates the reduction in the slab thickness as well as changes the failure mode of the slab from brittle to a more ductile manner.
Civil Engineering and Architecture, 2021
The application of steel fiber as added materials in a plain concrete shows many potential benefits in improving structural properties namely tensile and flexural strength. The plain concrete with steel fibers added is said to be effective for both short and long terms duration based on its characteristics mainly size, shape, volume, and distribution. Such potentials have made it a material worthy to be further studied. This research was conducted to assess the strength of a plain concrete with the addition of steel fibers in the conventional concrete slab. Several testings were conducted to determine the strength characteristic (compressive and flexural) of the control sample; conventional reinforced concrete (RC) and reinforced concrete with steel fibers added (RCSF). In this study, the commercial steel fibers taken from Dramix which is categorised under 5D-Type was added during the concrete mixing processes according to the three different percentages of 0.5%, 0.75% and 1.0%. Obtained result shows that the concrete with steel fibers added (0.5%) had the highest compressive strength while both reinforced concrete and concrete with 0.75% addition of steel fibers showed almost similar flexural strength value. Deflection testing was conducted on both RC slab and RCSF slab via Three-point bending test. It is found that the RC slab showed a higher mid-span deflection rate. Furthermore, result from the physical observation and measurement for crack propagation evaluation shows that RC slab had a wider cracking gap compared to RCSF. In a nutshell, steel fibers in plain concrete gives several advantages and provide an alternative for the construction practitioner in minimizing the construction cost while maintaining the quality and reducing the cracking problem mainly due to the structural properties of concrete.
Effect of steel fibers on the concrete strength grade: A review
IOP Conference Series: Materials Science and Engineering, 2020
The use of concrete reinforced with steel fibers has emerged as an effective material which has the advantages to be used in the most unconventional situations in reinforced concrete structures. These advantages involve reinforcements in structures that intend to resist loads in extreme conditions or change in the type of use, design and or construction errors, degradation of materials (carbonation or corrosion of reinforcement) and also the possible occurrence of accidents such as fires, floods, gusts of wind and earthquakes. In addition, the increasing use of this reinforcement system requires the development of more conclusive studies regarding the characteristics and behaviour of the steel fibers, as well as a critical evaluation of this material and its techniques. This manuscript presents a review on the interaction between steel fibre and the concrete substrate. Initially, a brief description of some fibers materials is made, followed by a summary of some works on adhesion between steel fibres and concrete under static loads. Finally, a summary of the few works on the main contribution of the steel fibers application to increase the strength after the cracking of concrete matrix during loading.
Experimental Study on The Steel Fiber Reinforcement Concrete
International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2023
Concrete is one of the world most widely used construction material. However, since the early 1800's, it has been known that concrete is weak in tension. Weak tensile strength combined with brittle behavior result in sudden tensile failure without warning. This is obviously not desirable for any construction material. Thus, concrete requires some form of tensile reinforcement to compensate its brittle behavior and improve its tensile strength and strain capacity to be used in structural applications. Historically, steel has been used as the material of choice for tensile reinforcement in concrete. Unlike conventional reinforcing bars, which are specifically designed and placed in the tensile zone of the concrete member, fibers are thin, short and distributed randomly throughout the concrete member. Fibers are commercially available and manufactured from steel, plastic, glass and other natural materials. Steel fibers can be defined as discrete, short length of steel having ratio of its length to diameter (i.e. aspect ratio) in the range of 20 to 100 with any of the several cross-section, and that are sufficiently small to be easily and randomly dispersed in fresh concrete mix using conventional mixing procedure. The random distribution results in a loss of efficiency as compared to conventional rebars, but the closely spaced fibers improve toughness and tensile properties of concrete and help to control cracking. In many situations it is prudent to combine fiber reinforcement with conventional steel reinforcement to improve performance. Fibre Reinforced Concrete (FRC) is defined as a composite material essentially consisting of conventional concrete or mortar reinforced by the random dispersal of short, discontinious, and discrete fine fibres of specific geometry. Since Biblical times, approximately 3500 years ago, brittle building materials, e.g. clay sun baked bricks, were reinforced with horse-hair, straw and other vegetable fibres. Although reinforcing brittle materials with fibers is an old concept, modern day use of fibers in concrete is only started in the early 1960s. Realizing the improved properties of the fiber reinforced concrete products, further research and development on fiber reinforced concrete (FRC) has been initiated since the last three decades. This paper presents an overview of the mechanical properties of Steel Fiber Reinforced Concrete (SFRC), its advantages, and its applications.
Effects of Steel Fibres on Concrete Properties and Flexural Behaviour of Reinforced Concrete Slabs
2017
Concrete is a material that is good in compression but weak in tension. Enhancing the tensile properties of concrete will lead to its greater application in construction. It was reported that improvement on the mechanical properties of reinforced concrete structure can be achieved by the inclusion of short fibres. The use of short steel fibres have been reported to increase the toughness, abrasion, impact resistances and allow for decrease in concrete slab thickness. This paper focuses on the study conducted in the laboratory on the effect of steel fibre on concrete properties and behaviour of steel fibre reinforced concrete slabs under flexure with different amount of tensile reinforcements. A number of concrete cubes and prisms with and without steel fibres, 0%, 0.5%, 1.0%, 1.5% and 2.0% together with four reinforced concrete slabs having different amount of tensile reinforcement were cast and tested to failure in flexure. The optimum dosage of steel fibre to be included in concre...
Experimental analysis of steel fiber reinforced concrete beams in shear
Revista IBRACON de Estruturas e Materiais
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...
The Effect Of Steel Fiber As Additional Reinforcement In The Reinforced Concrete Beam
Steel fiber reinforced concrete has been increasingly used in structural applications during the last four decades. It is generally accepted that addition of steel fibers significantly increases tensile toughness and ductility, also slightly enhances the flexural strength. Effects of steel fibers as addition reinforcement in reinforced concrete (RC) beams are the main objectives of this study. The hooked-end steel fibers with the dimensions of 0.75 mm in diameter, 33 mm in length and with the aspect ratio of 44 were used in this study. Initially the optimum percentage addition of steel fibers in concrete was determined. In order to accomplish this task, eighteen concrete beams with the same mix proportioning of concrete and different volume fractions of steel fiber (0.5 % and 0.75%) were prepared. Then, by determining the flexural strength and deflection of samples, it was concluded that the optimum volume fraction was 0.50 % (0.44 kg). In the next step,the flexural behavior and deflection of RC beams with the addition of steel fibers in concrete was considered. The study was conducted on two types of beam which is beam with 5 links and no steel fibers as a contol beam and the other one was beam with 4 links and 0.50% and 0.75% volume of steel fibers. The overall dimensions of the beams were 150 mm in height, 150 mm in width, and 500 mm in length. The beams were tested under four-point loading test. The results showed that addition of steel fibers increases the cracking load, load, stiffness and ductility of the concrete beams.