scholarly journals Design of reinforced concrete beams with steel fibers in the ultimate limit state

2018 ◽  
Vol 11 (5) ◽  
pp. 997-1024
Author(s):  
T. E. T. BUTTIGNOL ◽  
J. F. FERNANDES ◽  
T. N. BITTENCOURT ◽  
J. L. A. O. SOUSA
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Limit State ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Ultimate Limit State ◽  
Bending Tests

Abstract This paper carries out a design analysis of reinforced concrete beams with steel fibers following the fib Model Code 2010 (MC 2010) procedures. The values obtained from the design calculations are compared with the experimental results of reinforced concrete beams with 20kg/m3 and 60 kg/m3 of steel fibers submitted to four-point bending tests. In the first part, the procedures for the classification and characterization of the material are explained. The experimental results of three-point bending tests performed on notched steel fiber reinforced concrete (FRC) beams following EN 14651 procedures are described. Moreover, the characterization of the FRC beams according to MC 2010, are carried out. In the second part, the flexural design of reinforced concrete beams with steel fibers, according to MC 2010, is carried out. A sectional analysis is performed in order to obtain the moment-curvature and the force-vertical displacement curves. The theoretical values are compared with the experimental results. Besides, a linear statistic analysis by means of the Rule of Mixture is carried out in order to analyze the variation of the flexural capacity of the reinforced beams with different amounts of steel fibers. The results demonstrated that the design rules described in the MC 2010 are on the safe side. The flexural resistance of concretes with different amounts of fiber incorporation can be determined by the Rule of Mixture, which has shown a high correlation factor (R2) with the experimental values.

Study on Retrofitting and Strengthening of Reinforced Concrete Beams Using Fibrous Concrete

2021 ◽  
Vol 9 (8) ◽  
pp. 1676-1684
Author(s):  
Natalia Sharma
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Cement Matrix ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete

Abstract: Reinforced concrete structures are frequently in need of repair and strengthening as a result of numerous environmental causes, ageing, or material damage under intense stress conditions, as well as mistakes made during the construction process. RC structures are repaired using a variety of approaches nowadays. The usage of FRC is one of the retrofitting strategies. Steel fiber reinforced concrete (SFRC) was used in this investigation because it contains randomly dispersed short discrete steel fibers that operate as internal reinforcement to improve the cementitious composite's characteristics (concrete). The main rationale for integrating small discrete fibers into a cement matrix is to reduce the amount of cement used. The principal reason for incorporating short discrete fibers into a cement matrix is to reduce cracking in the elastic range, increase the tensile strength and deformation capacity and increase the toughness of the resultant composite. These properties of SFRC primarily depend upon length and volume of Steel fibers used in the concrete mixture. In India, the steel fiber reinforced concrete (SFRC) has seen limited applications in several structures due to the lack of awareness, design guidelines and construction specifications. Therefore, there is a need to develop information on the role of steel fibers in the concrete mixture. The experimental work reported in this study includes the mechanical properties of concrete at different volume fractions of steel fibers. These mechanical properties include compressive strength, split tensile strength and flexural strength and to study the effect of volume fraction and aspect ratio of steel fibers on these mechanical properties. However, main aim of the study was significance of reinforced concrete beams strengthened with fiber reinforced concrete layer and to investigate how these beams deflect under strain. The objective of the investigation was finding that applying FRC to strengthen beams enhanced structural performance in terms of ultimate load carrying capacity, fracture pattern deflection, and mode of failure or not.

scholarly journals Shear Performance of Steel Fibers in Reinforced Concrete Beams

2019 ◽  
Vol 9 (2) ◽  
pp. 345-350
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Resistance Mechanism ◽  
Shear Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Shear Reinforcement ◽  
Shear Span

Over the past few decades, a significant growth was observed on utilization of steel fibers in Reinforced Concrete (R.C) members. Past research studies on hybrid concrete endorsed optimum utilization of steel fibers (1.5% by volume) as it effectively contributed to improve flexural properties of reinforced concrete members such as R.C beams and slabs .But the contribution of fibers against shear resistance mechanism of R.C beams are not identified well in the previous research. In this context an experimental program was conducted to find Shear contribution and associated Parameters of fibers in the Steel Fiber Reinforced Concrete (SFRC) beams. A series of test programmes are conducted on three full scale reinforced concrete beams (NSF: No steel fibers, BSF1: Steel fibers in shear span, BSF2: Steel fibers in full span) with different configuration of shear reinforcement by using varied range of SFRC in the tested beam. The test results evaluated on the basis of strength and durability aspects at service loads and limit of failure conditions. The results concluded that the presence of steel fibers in reinforced concrete beam significantly contributed to induce shear resistance mechanism and ductile property of R.C beam. This improvement observed in BSF2, when the SFRC constituted in shear span region and the rest of R.C beam arranged with minimum conventional stirrups as shear reinforcement. Further the steel fibers possess good compatibility with concrete and steel reinforcement ,which enhance mechanical and serviceability conditions of R.C beam such as shear strength, ductility, stiffness with respect to strength and deflection, crack width during serviceability conditions of the beam.

scholarly journals Influence of Fiber Content on Shear Capacity of Steel Fiber-Reinforced Concrete Beams

Fibers ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 102 ◽  
Author(s):  
Juan Andres Torres ◽  
Eva O.L. Lantsoght
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume

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, 10 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 was analyzed based on results reported in the literature, as well as based on the expressions derived for estimating the shear capacity of steel fiber-reinforced concrete beams. The outcome of these experiments is that a fiber percentage of 1.2% or fiber factor of 0.96 can be used to replace minimum stirrups according to ACI 318-14 and a 0.6% fiber volume fraction or fiber factor of 0.48 to replace minimum stirrups according to Eurocode 2. A fiber percentage of 1.2% or fiber factor of 0.96 was observed to change the failure mode from shear failure to flexural failure. The results of this study support the inclusion of provisions for steel fiber-reinforced concrete in building codes and provides recommendations for inclusion in ACI 318-14 and Eurocode 2, so that a wider adoption of steel fiber reinforced concrete can be achieved in the construction industry.

scholarly journals Influence of Fiber Content on Shear Capacity of Steel Fiber Reinforced Concrete Beams

2019 ◽  
Author(s):  
Juan Andres Torres ◽  
Eva O.L. Lantsoght
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume

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 the literature, as well as based on the expressions derived for estimating the shear capacity of steel fiber reinforced concrete beams. The outcome of these experiments is that a fiber percentage of 1.2% or fiber factor of 0.96 can be used to replace minimum stirrups according to ACI 318-14 and a 0.6% fiber volume fraction or fiber factor of 0.48 to replace minimum stirrups according to Eurocode 2. A fiber percentage of 1.2% or fiber factor of 0.96 was observed to change the failure mode from shear failure to flexural failure. The results of this presented study support the inclusion of provisions for steel fiber reinforced concrete in building codes and provides recommendations for inclusion in ACI 318-14 and Eurocode 2, so that a wider adoption of steel fiber reinforced concrete can be achieved in the construction industry.

scholarly journals Reliability of reinforced concrete beams designed in accordance with Brazilian code NBR-6118:2014

2019 ◽  
Vol 12 (5) ◽  
pp. 1086-1125
Author(s):  
M. SCHERER ◽  
I. B. MORSCH ◽  
M. V. REAL
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Limit State ◽  
Design Tool ◽  
Reinforced Concrete Beams ◽  
Ultimate Limit State ◽  
Safety Level ◽  
Design Variables ◽  
Live Loads ◽  
Ultimate Limit

Abstract This paper aims to evaluate the reliability indexes of reinforced concrete beams designed in accordance with brazilian code NBR-6118:2014 in relation to the ultimate limit state of flexure. The main statistics of the resistance model are obtained through Monte Carlo simulation using ANSYS software and its probabilistic design tool. The reliability indexes are evaluated by FORM, being performed a parametric study in order to assess the influence of the main design variables on the safety level reached. It can be noticed that the reliability indexes are shown unsatisfactory in the combinations which the live loads are predominant.

Flexural Performance of Reinforced Concrete Built-up Beams with SIFCON

2020 ◽  
Vol 38 (5A) ◽  
pp. 669-680
Author(s):  
Ghazwan K. Mohammed ◽  
Kaiss F. Sarsam ◽  
Ikbal N. Gorgis
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Concrete Beams ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Conventional Concrete ◽  
Flexural Performance ◽  
Load Carrying ◽  
Fiber Concrete

The study deals with the effect of using Slurry infiltrated fiber concrete (SIFCON) with the reinforced concrete beams to explore its enhancement to the flexural capacity. The experimental work consists of the casting of six beams, two beams were fully cast by conventional concrete (CC) and SIFCON, as references. While the remaining was made by contributing a layer of SIFCON diverse in-depth and position, towards complete the overall depths of the built-up beam with conventional concrete CC. Also, an investigation was done through the control specimens testing about the mechanical properties of SIFCON. The results showed a stiffer behavior with a significant increase in load-carrying capacity when SIFCON used in tension zones. Otherwise high ductility and energy dissipation appeared when SIFCON placed in compression zones with a slight increment in ultimate load. The high volumetric ratio of steel fibers enabled SIFCON to magnificent tensile properties.

Sign in / Sign up

Export Citation Format

Share Document