The diagonal tension behavior of fiber reinforced concrete beams (original) (raw)

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.

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...

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.

Shear behaviour of fiber reinforced concrete beams

Cement and Concrete Composites, 1997

This paper presents the results of shearl'exure tests on steel and polypropylene fiber reinforced concrete beams. In addition to analyzing the influence of fibers on the structural peeormance in situations of di.erent ratios of shear reinforcement, some aspects of the properties of fresh and hardened concrete are introduced. Fourteen square-section beams were tested. The beams were prepared from seven different mix proportions, varying the type and the volume of fiber added. There were two beams for each composite mix: one model with and the other without stirrups. The main alterations resulting from the use of fibers were increased shear strength, stifj%ess (particularly after first cracking stage) and ductility. Other parameters used in analyzing performance were the properties of the hardened concrete (compressive strength, tensile strength, and modulus of elasticity), and stresses in the stirrups, in the longitudinal reinforcement and in the concrete (at the web and compression zone).

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...

Shear Behavior of Steel Fiber Reinforced Concrete Beams

ACI Structural Journal, 1993

Twelve simply-supported steel fiber reinforced concrete (SFRC) wide beams without conventional stirrups were tested to investigate their shear behavior. The flexure mode of failure was secured for all of the specimens to allow for shear mode of failure. The variables were fiber volumetric ratio, concrete compressive strength, longitudinal reinforcement ratio and shear span-to-depth ratio. Eight tested beams were steel fiber reinforced concrete wide beams and four beams were reinforced concrete wide beams without steel fiber for comparison purposes. End-hooked steel fibers of volumetric ratio ranging from 0% to 1.25% were used in the specimens. All beams were tested under four-point loading to investigate their behavior in shear, cracking pattern, ultimate capacity and ductility. Test results showed that the shear cracking, the ultimate shear strength and ductility increased with increasing fiber volumetric ratio, decreasing shear span to depth ratio, increasing concrete compressive strength and increasing longitudinal reinforcement ratio. The using of a dose of 0.75% fiber content in the wide beams without shear stirrups was adequate to achieve the ultimate resistance that is the same as the conventional RC wide beam with conventional stirrups. Evaluation of the ultimate shear strength of the SFRC wide beams based on previous models is presented.

Shear capacity of fiber-reinforced concrete beams without transverse reinforcement

IOP Conference Series: Materials Science and Engineering

This study studied the effect of using fiber on the shear strength of concrete beams without transverse reinforcement. The concrete mixture does not use coarse aggregate and uses stainless steel fiber with a diameter of 0.2 mm and a length of 36 mm. This study explains the effect of concrete quality on shear strength that can be carried by concrete beams with a ratio of 45 / 10.5, 25 / 10.5 and 20 / 10.5. The making of test specimens in this study was a beam of varying lengths of 110 cm, 70 cm and 60 cm while a width of 7 cm, and a height of 12.5 cm. From the test results, the shear stress value is calculated using the formula v / (b x d x ¥ (f'c)) > 2 in international units, in which the shear capacity value is bigger than the code states. Diagonal tension failure occurs on 110cm beam and shear tension failure on 70 cm and 60 cm beams.

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.

Shear Behavior of Fiber Reinforced Concrete Beams

2016

Shear strength of fiber reinforced concrete (FRC) has prime importance in structural design. Concrete members like brackets, corbels and ledger beams may fail in shear. Such failure can be sudden and brittle. The presence of fibers positively affects the behavior of concrete, as it increases the residual shear transfer and reduces the formation and extension of cracks. As many parameters affect it, shear strength of FRC could not be precisely detected. Experimental investigation was carried out to study the shear transfer of un-cracked fibrous concrete. The study investigates the shear strength of FRC beams. The experimental parameters were the type and the percentage of fibers volume fraction and the presence of stirrups in reinforced concrete beams. Test results showed that the presence of fibers resulted in higher values of shear strength, stiffness, ductility and controlled the concrete cracking behavior. Instead of glass fibers, the use of steel fibers improved overall shear be...

Numerical analysis of concrete beams reinforced with steel fibers

Present research was aimed at experimental and theoretical investigation of tension-stiffening of steel fiber reinforced concrete beams. The paper reports results of the experimental program consisted of five beams, which were reinforced with three bars of tensile reinforcement 10 mm in diameter. The beams had different contents of fibers, i.e. 0, 0.3, 0.5, 1.0 and 1.5% by volume. Prior to the tests, measurement on concrete shrinkage was performed. It has been shown that influence of steel fiber deformations is significant until the fiber content does not exceed 1% of element volume. Until this limit, the efficiency of fiber increases proportionally to its content, whereas its influence is insignificant above the limit.