Minimum torsional reinforcement ratio for reinforced concrete members with steel fibers

2019 ◽  
Vol 207 ◽  
pp. 460-470 ◽  
Author(s):  
Hyunjin Ju ◽  
Deuck Hang Lee ◽  
Kang Su Kim
Keyword(s):  
Reinforced Concrete ◽  
Reinforcement Ratio ◽  
Steel Fibers ◽  
Concrete Members

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.

Cracking behaviour of concrete beams reinforced with fiber reinforced plastic rebars

1996 ◽  
Vol 23 (6) ◽  
pp. 1172-1179 ◽  
Author(s):  
R. Masmoudi ◽  
B. Benmokrane ◽  
O. Chaallal
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Concrete Beams ◽  
Reinforcement Ratio ◽  
Test Results ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Concrete Members ◽  
Reinforced Plastic ◽  
Cracking Pattern

This paper presents the results of an experimental investigation on the cracking behaviour of concrete beams reinforced with fiber reinforced plastic rebars. The effects of reinforcement ratio on the cracking pattern, crack spacing, cracking moment, and crack width are investigated. The test results indicate that the reinforcement ratio has no meaningful effect on the cracking moment, which can be calculated as recommended by the ACI code. Also, the use of the equations adopted by ACI and the European codes for the prediction of crack width of conventionally reinforced concrete members is investigated and due modifications are made. Both relationships show good correlation with the test results; and the prediction of crack width of concrete beams reinforced with these two types of fiber reinforced plastic rebars is now possible. Key words: beam, cracking behaviour, cracking moment, crack width, fiber reinforced plastic, flexure, rebars, reinforced concrete, reinforcement ratio.

Analysis on Flexural Capacity of FRP Reinforced Concrete Members

2012 ◽  
Vol 446-449 ◽  
pp. 98-101
Author(s):  
Chun Xia Li ◽  
Zhi Sheng Ding ◽  
Shi Lin Yan
Keyword(s):  
Reinforced Concrete ◽  
Material Properties ◽  
Failure Modes ◽  
Reinforcement Ratio ◽  
Flexural Capacity ◽  
Steel Reinforced Concrete ◽  
Concrete Members

The balanced reinforcement ratio of FRP-reinforced concrete members and the flexural capacity under two different failure modes (concrete crushing and FRP rupture) are established, based on the analysis on flexural capacity of steel-reinforced concrete members in current concrete code. The effect of material properties on the balanced ratio, the variation of flexural capacity with different reinforcement ratio and a simplified nominal flexural capacity under FRP-rupture failure are derived.

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.

scholarly journals Influence of tensile softening of concrete on crack development and failure in concrete and reinforced concrete beams

2019 ◽  
Vol 68 (1) ◽  
pp. 213-223 ◽  
Author(s):  
Marta Słowik
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Plain Concrete ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Concrete Members ◽  
Cracking Process ◽  
Tensile Softening

In the paper, the own test results were presented. The experimental investigation was focused at determining the cracking and load capacity of beams made of concrete. The beams were characterized by different longitudinal reinforcement ratio from zero — plain concrete beams, through low ratio 0.12% — slightly reinforced concrete beams, middle ratio 0.9% — typical reinforced concrete beams, up to the ratios 1.3% and 1.8% — higher reinforced concrete beams. On the basis of the performed experiments and the results of numerical calculations, the process of crack’s formation and crack’s development in plain concrete, slightly reinforced concrete and reinforced concrete beams with different reinforcement ratio was described. When discussing cracking process in the beams, the contribution of strain softening of tensile concrete in the microcracked zone on the character of beams’ failure was analysed as well. Keywords: civil engineering, concrete and reinforced concrete members, cracking and load capacity.

scholarly journals Research on the Estimation Method of the Stiffness Degeneration Index of Reinforced Concrete Members

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yukui Wang ◽  
Zhefeng Liu ◽  
Weijun Yang ◽  
Jian Wang ◽  
Xiao Zheng
Keyword(s):  
Reinforced Concrete ◽  
Estimation Method ◽  
Reinforcement Ratio ◽  
Stiffness Degradation ◽  
Design Parameters ◽  
Transverse Reinforcement ◽  
Degradation Index ◽  
Cumulative Energy ◽  
Concrete Members ◽  
Prediction Reliability

Based on variable amplitude displacement cycle tests of 24 reinforced concrete members with different reinforcement conditions, the stiffness degradation index was proposed to describe the damage. The relationship between the stiffness degradation index, the displacement history, and the cumulative energy dissipation was studied; on this basis, an estimation method for the stiffness degradation index was proposed. By comparing the experimental values and estimated values of the stiffness degradation index, the proposed method provides promising prediction reliability and accuracy. The stiffness degradation index has an effective relationship with the structural design parameters. Based on the stiffness degradation index, the reinforced concrete members can be divided into five performance levels: no damage (DK,k < 0), mild damage (0 < DK,k ≤ 0.3), moderate damage (0.3 < DK,k ≤ 0.7), severe damage (0.7 < DK,k ≤ 0.9), and destruction (0.9 < DK,k ≤ 1), which can provide a good reference for the seismic design of reinforced concrete members. The increase in the transverse reinforcement ratio can significantly reduce the stiffness damage, and the effect is more obvious under the conditions of small ductility. Under the same conditions, the smaller the ductility condition is, the smaller the stiffness damage of the reinforced concrete members will be. Therefore, the control of the ductility condition and the increase in the transverse reinforcement ratio are stable and effective methods for controlling the stiffness damage of reinforced concrete members.

scholarly journals The analysis of load carrying capacity and cracking of slightly reinforced concrete members in bending

2008 ◽  
Vol 2 (1) ◽  
pp. 065-078
Author(s):  
Marta Słowik
Keyword(s):  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Concrete Beams ◽  
Plain Concrete ◽  
Reinforcement Ratio ◽  
Reinforced Concrete Beams ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Concrete Members ◽  
Load Carrying

Slightly reinforced concrete members are the members made by concrete with reinforcement less than minimum given in codes for reinforced concrete ones. Plain concrete and slightly reinforced concrete members in bending are treated in the same way during the dimensioning and the influence of longitudinal reinforcement on the load carrying capacity is not taken into account. The mechanism of work and crack formation in slightly reinforced concrete members is not completely recognized. The author’s own research program was made. The experiment was aimed at the determination of cracking moment and load carrying capacity of slightly reinforced concrete beams with different reinforcement ratio. Also plain concrete beams and the typical reinforced concrete beam were tested. The analysis of the obtained values of maximum bending moment and crack’s widths was made according to the reinforcement ratio. The analysis of test results shows how the presence of longitudinal steel bars in concrete members, even when reinforcement ratio is low, changes cracking process and influences the value of cracking moment in flexural members. On the basis of test results, the method how to calculate the load carrying capacity of slightly reinforced concrete elements in bending has been proposed.

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