scholarly journals FIBER SEGMENTATION IN CRACK REGIONS OF STEEL FIBER REINFORCED CONCRETE USING PRINCIPAL CURVATURE

2018 ◽  
Vol 37 (2) ◽  
pp. 127 ◽  
Author(s):  
Markus Kronenberger ◽  
Katja Schladitz ◽  
Bernd Hamann ◽  
Hans Hagen
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Three Dimensional ◽  
Volume Density ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Principal Curvatures ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume

This paper tackles the non-trivial image-processing task to segment hook-ended fibers in three-dimensional images. For this purpose, a novel segmentation method is presented that relies on the following observation: For a single fiber the configurations of principal curvatures that can occur on its surface are limited. Deviations from these configurations indicate potential overlaps of fibers. The method that was developed based on this observation is used to separate several simulated clusters of touching fibers as a proof-of-concept. Further, it is applied to two images of cracked steel fiber reinforced concrete specimens arising from a 4-point bending test. The method's performance is compared to manual separation. Overall, we can state that the proposed method yields satisfying results when data meets the following criteria: Low fiber volume density, circular fiber cross section and sufficient spatial resolution of fiber-fiber contacts.

scholarly journals Using Steel Fiber-Reinforced Concrete Precast Panels for Strengthening in Shear of Beams: An Experimental and Analytical Investigation

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Pitcha Jongvivatsakul ◽  
Linh V. H. Bui ◽  
Theethawachr Koyekaewphring ◽  
Atichon Kunawisarut ◽  
Narawit Hemstapat ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Fiber Reinforced Concrete ◽  
Experimental Program ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
Simple Formulation

In this paper, the performances of reinforced concrete (RC) beams strengthened in shear with steel fiber-reinforced concrete (SFRC) panels are investigated through experiment, analytical computation, and numerical analysis. An experimental program of RC beams strengthened by using SFRC panels, which were attached to both sides of the beams, is carried out to investigate the effects of fiber volume fraction, connection type, and number and diameter of bolts on the structural responses of the retrofitted beams. The current shear resisting model is also employed to discuss the test data considering shear contribution of SFRC panels. The experimental results indicate that the shear effectiveness of the beams strengthened by using SFRC panels is significantly improved. A three-dimensional (3D) nonlinear finite element (FE) analysis adopting ABAQUS is also conducted to simulate the beams strengthened in shear with SFRC panels. The investigation reveals the good agreement between the experimental and analytical results in terms of the mechanical behaviors. To complement the analytical study, a parametric study is performed to further evaluate the influences of panel thickness, compressive strength of SFRC, and bolt pattern on the performances of the beams. Based on the numerical and experimental analysis, a shear resisting model incorporating the simple formulation of average tensile strength perpendicular to the diagonal crack of the strengthened SFRC panels is proposed with the acceptable accuracy for predicting the shear contribution of the SFRC system under various effects.

scholarly journals Failure mode in shear of steel fiber reinforced concrete beams

2018 ◽  
Vol 163 ◽  
pp. 02003 ◽  
Author(s):  
Julita Krassowska ◽  
Marta Kosior-Kazberuk
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Fibre Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Steel Fibres

Experimental tests were carried out to assess the failure model of steel fiber reinforced concrete beams. Experimental research was focused on observing changes in the behavior of the tested elements depending on the amount of shear reinforcement and the fiber. Model two-span beams with a cross-section of 80x180 mm and a length of 2000 mm were tested. The beams had varied stirrup spacing. The following amounts of steel fibres in concrete were used: 78.5 kg/m3 (1.0%) i 118 kg/m3 (1.5%). Concrete beams without fibres were examined at the same time. The beams were loaded in a five-point bending test until they were destroyed. Shear or bending capacity of the element was observed. Fibre reinforced concrete beams were not destroyed rapidly, but they kept their shape consistent under load. Larger number of diagonal cracks with a smaller width were observed in fibre reinforced concrete beams. Failure of concrete beams without fibres was rapid, with a characteristic brittle cracking. Steel fibres revealed the ability to transfer significant shear stress after cracking in comparison to plain concrete.

Experiment Research on the Steel Fiber Reinforced Concrete in the Acid Environment

2011 ◽  
Vol 224 ◽  
pp. 224-228 ◽  
Author(s):  
Yue Qiang ◽  
Li Li ◽  
Ze Ping He
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Ph Value ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Inorganic Acid ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
Volume Rate ◽  
Corrosion Coefficient

For the purpose of studying the resistance of steel fiber reinforced concrete against the corrosion of different acid, test compressive strength and flexural strength of the steel fiber reinforced concrete of different volume rate after the corrosion of organic and inorganic acid, and express experiment results with the form of comprehensive corrosion coefficient and the flexural corrosion coefficient in order to reflect the corrosion degree. The results shows that, the organic corrosion has a stronger corrosion effect on the steel fiber reinforced concrete than the inorganic acid under the environment of same PH value. When steel fiber volume rate is 1.5%, the corrosion resistance capacity of the steel fiber reinforced concrete is best.

scholarly journals TENSILE BEHAVIOUR OF ULTRA-HIGH-PERFORMANCE STEEL FIBER REINFORCED CONCRETE

2020 ◽  
Author(s):  
Yuechen Yang ◽  
Mohammed Ismail ◽  
Stavroula Pantazopoulou ◽  
Dan Palermo
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Tensile Behaviour ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Splitting Test ◽  
High Performance Steel

Recent developments in the area of Ultra-High-Performance Steel Fiber Reinforced Concrete (UHP-SFRC) enables reduction in steel reinforcement, and has led to enhanced ductility and toughness of structural components owing to its resilient tensile behaviour. This paper presents the results of an experimental study conducted to investigate the tensile behaviour of UHP-SFRC. Four commercial mixes and two in-house mixes were evaluated using the procedures prescribed in the 2018 edition of Annex 8.1 of CSA-S6. Tensile strength of UHP-SFRC was quantified and correlated through the direct tension test, splitting test, inverse analysis of four-point bending test using either code expressions or nonlinear finite element analysis, and a calibrated empirical expression that links this property to the cylinder compressive strength. In addition, the effect of important parameters on flexural strength including casting methodology, volumetric ratio of steel fibers, and aspect ratio (shear span to depth ratio) of bending prisms have been assessed.

Shrinkage Performance of Adherence of New Steel Fiber-Reinforced Concrete to Old Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 3569-3574
Author(s):  
Hong Qiang Cheng ◽  
Dan Ying Gao
Keyword(s):  
Reinforced Concrete ◽  
Fiber Volume Fraction ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Fiber Volume ◽  
Shrinkage Force ◽  
The Difference

Shrinkage experiments were done to determine the influence of the volume fraction of steel fiber-reinforcement on the bonding behavior between new concrete and old concrete. The mechanics of the model of restricted shrinkage upon the adherence of new steel fiber reinforced concrete to old concrete are described. The results demonstrate that the difference of shrinkage between the new and the old concrete can been reduced by adding steel fiber to the new concrete. The decrease of shrinkage difference reduces the shrinkage force at the adhesive interface, which improves the adhesion of new concrete to old concrete and the magnitude of the decrease of shrinkage difference is correlated to the steel fiber volume fraction.

Experimental Research of Bending Capacity of Normal Section of Steel Fiber Reinforced Concrete Wall-Beams Simply Supported

2012 ◽  
Vol 193-194 ◽  
pp. 1365-1370
Author(s):  
Su Qi ◽  
Ye Zhang ◽  
Shu Hao Liu ◽  
Xiong Song
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Concrete Wall ◽  
Fiber Volume ◽  
Normal Section ◽  
Simply Supported ◽  
Reinforced Concrete Wall

Because the joists in the wall-beams are in eccentric tension during work and the concrete tensile strength is low, the bending capacity of normal section of wall-beams is not too large. Steel fibers mixed into the concrete, playing enhancement and crack-resistance roles would lead to changes in the nature of concrete materials so that it is impossible to fully use the existing research results of ordinary concrete wall-beams simply supported when studying bending behavior of normal section of steel fiber reinforced concrete wall-beams simply supported. Therefore, it is necessary to do pilot studies on bending behavior of normal section of steel fiber reinforced concrete wall-beams simply supported. Based on the vertical static load test of 12 steel fiber reinforced concrete wall-beams simply supported specimens under different fiber volume ratio conditions, the strains of steel and concrete, cracking load, failure load and development situation in the cracks were tested while working characteristics of steel fiber reinforced concrete wall-beams simply supported were studied. This paper discussed the effect of fiber volume ratio on cracking moment and ultimate moment of steel fiber reinforced concrete wall-beams simply supported, which shows that the optimum mixing amount of steel fiber is 1.2%. The conclusion is of great significance in both theory and engineering practice, and it helps to guide the application of practical engineering.

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 Mechanical Properties of Steel Fiber-Reinforced Concrete by Vibratory Mixing Technology

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yuanxun Zheng ◽  
Xiaolong Wu ◽  
Guangxian He ◽  
Qingfang Shang ◽  
Jianguo Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Steel Fiber Concrete ◽  
Mixing Method ◽  
Splitting Tensile Test

As a kind of important engineering material, steel fiber-reinforced concrete was used widely in civil engineering. Up to now, steel fiber-reinforced concrete was usually produced by the traditional mixing method. For the reason of uniform distribution of fiber, the reinforcement of mechanical properties of concrete was inadequately performed. In this paper, C50 steel fiber-reinforced concrete and C60 steel fiber-reinforced concrete were manufactured by traditional mixing and vibratory mixing methods, respectively, and then, the cube compression test, flexural test, splitting tensile test, and the bending test were carried out. The reinforcement effects of mechanical properties were analyzed by comparing the traditional mixing and vibratory mixing methods. The results show that vibratory mixing can effectively improve the distribution of steel fibers in concrete and can increase the density of steel fiber concrete, and therefore, it effectively improves the mechanical properties of steel fiber-reinforced concrete when compared to the traditional mixing method.

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