scholarly journals Experimental Study on Evaluation of Replacing Minimum Web Reinforcement with Discrete Fibers in RC Deep Beams

Fibers ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 73
Author(s):  
Murali Sagar Varma Sagi ◽  
Chandrashekhar Lakavath ◽  
S. Suriya Prakash ◽  
Akanshu Sharma
Keyword(s):  
Volume Fraction ◽  
Peak Load ◽  
Plain Concrete ◽  
Concrete Specimen ◽  
Test Results ◽  
Deep Beams ◽  
Hybrid Fibers ◽  
Synthetic Fibers ◽  
Web Reinforcement ◽  
The Individual

This study investigates the possibility of replacing the minimum web reinforcement in deep beams with discrete fibers. Additionally, the equivalent dosage of fibers required to obtain similar performance of the deep beam with minimum web reinforcement is investigated. Deep beams made of plain concrete with no fibers, beams with minimum web reinforcement as per AASHTO LFRD recommendations (0.3% in both horizontal and vertical), and with a 0.5% volume fraction of steel, macro-synthetic and hybrid fibers are tested at a shear span to height ratio (a/h) of one. Test results show that the presence of 0.3% web reinforcement in horizontal and vertical directions increased the peak load by 25% compared to the plain concrete beams. However, it did not significantly change the first diagonal crack load. With the addition of 0.5% of steel, macro-synthetic and hybrid fibers, the peak load increased by 49%, 42%, and 63%, respectively, compared to the plain concrete specimen. The addition of steel fibers significantly improved the first cracking load. In contrast, macro-synthetic fibers did not affect the first cracking load but improved the ductility with higher deflections at peak. Hybridization of steel and macro synthetic fibers showed improved performance compared to the individual fibers of the same volume in peak load and ductility. Test results showed that a 0.5% volume fraction of discrete macro steel or synthetic or hybrid fibers can be used to completely replace the minimum web reinforcement (0.3% in both directions).

scholarly journals Strengthening of self-compacting reinforced concrete deep beams containing circular openings with CFRP

2018 ◽  
Vol 162 ◽  
pp. 04015
Author(s):  
Nabeel Al-Bayati ◽  
Bassman Muhammad ◽  
Murooj Faek
Keyword(s):  
Ultimate Load ◽  
Test Results ◽  
Load Path ◽  
Deep Beams ◽  
Self Compacting Concrete ◽  
Reinforced Polymer ◽  
Web Reinforcement ◽  
Externally Bonded ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

This paper shows the behavior of reinforced self-compacting concrete deep beams with circular openings strengthened in shear with various arrangements of externally bonded Carbon Fibre Reinforced Polymer (CFRP). Six simply supported deep beams were constructed and tested under two points load up to the failure for this purpose. All tested beams had same geometry, compressive strength, shear span to depth ratio, main flexural and web reinforcement. The variables considered in this study include the influence of fiber orientation, utilizing longitudinal CFRP strips with vertical strips and area of CFRP. The test results indicated that the presence of the circular openings in center of load path reduce stiffness and ultimate strength by about 50% when compared with solid one, also it was found that the externally bonded CFRP can significantly increase the ultimate load and enhance the stiffness of deep beam with openings.

Mechanical Properties of Hybrid Basalt-Polyvinyl Alcohol (PVA) Fiber Reinforced Concrete

2017 ◽  
Vol 744 ◽  
pp. 3-7 ◽  
Author(s):  
Asif Jalal ◽  
Nasir Shafiq ◽  
Ehsan Nikbakht ◽  
Rabinder Kumar ◽  
Muhammad Zahid
Keyword(s):  
Reinforced Concrete ◽  
Volume Fraction ◽  
Peak Load ◽  
High Strength ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Maximum Deflection ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Pva Fiber

This study focuses on the study of the mechanical behavior of non-metallic hybrid Basalt-PVA fiber reinforced concrete. Total five mixes were investigated with one control plain concrete and four with fiber volume fraction of 0.3%, 0.6%, 0.9% and 1.2%. Basalt and PVA were used in same quantity. Fiber decreased workability, therefore superplasticizer was used to maintain workability constant. The increase in superplasticizer and fiber content decreased compression, split tensile and flexure strengths because of formation of big size pores. Whereas fiber enhanced the post peak load zone in the load-deflection curve. Fiber improved the bridging action by increasing energy absorption. Fiber vanished the brittle behavior of high strength concrete and increased first crack toughness, flexure toughness and also maximum deflection. 0.3% volume fraction of fiber was found to be optimum with the negligible decrease in compression, split tensile and flexure strength while caused the considerable increase in first crack toughness, flexure toughness, and maximum deflection.

Flexural Behaviour of Concrete Beams Bonded with Wire Mesh-Epoxy Composite

2014 ◽  
Vol 567 ◽  
pp. 411-416 ◽  
Author(s):  
Ismail M.I. Qeshta ◽  
Payam Shafigh ◽  
Mohd Zamin Jumaat ◽  
Aziz Ibrahim Abdulla ◽  
Ubagaram Johnson Alengaram ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Energy Absorption ◽  
Concrete Beams ◽  
Epoxy Composite ◽  
Plain Concrete ◽  
Concrete Specimen ◽  
Wire Mesh ◽  
Test Results ◽  
Flexural Behaviour ◽  
Flexural Performance

This paper investigates the flexural performance of plain concrete beams bonded with wire mesh-epoxy composite. A total of four beam specimens were prepared and tested. Three specimens were bonded with same amount of wire mesh-epoxy composite with varying composite width and one plain concrete specimen was used as a control. The effect of wire mesh-epoxy composite on enhancing the flexural behaviour of concrete beams as well as the effect of different configurations of composite was studied. Test results showedthat the wire mesh-epoxy composite increased the flexural strength of concrete beams. The increase in energy absorption of bonded beams was remarkable. In addition, specimen with large composite width showed better behaviour with respect to energy absorption capability.

scholarly journals Exploration of Characteristics of Steel Fiber Reinforced Concrete and Its Influence on Regular Concrete

2020 ◽  
Vol 9 (2) ◽  
pp. 209-212
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Natural Fibers ◽  
Plain Concrete ◽  
Fiber Content ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Synthetic Fibers

Concrete is the most widely used product in the construction sector mainly because of its properties and its capability to be moulded to any size. Plain concrete has low tensile strength and forms internal micro cracks. It has been proven that with the addition of natural fibers and synthetic fibers in concrete, it helps in the durability and functionality of structure. The steel fibers are added to the concrete in very low volume doses and it has been effective in decreasing the plastic shrinkage in cracking and also acting as a crack arrestor. In this journal, experimental analysis on steel fiber reinforced concrete is done on M30 and M50 mix with 0.5%, 1%, 1.5% and 2% volume fraction of steel fiber content and is compared with samples of 0% steel fiber content and these samples are investigated on their compressive, split tensile and flexural strengths.

scholarly journals Shear Behavior of Hybrid Fiber Reinforced Concrete Deep Beams

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2023 ◽  
Author(s):  
Kaize Ma ◽  
Ting Qi ◽  
Huijie Liu ◽  
Hongbing Wang
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Shear Behavior ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Deep Beam ◽  
Hybrid Fiber ◽  
Deep Beams ◽  
Hybrid Fibers ◽  
Web Reinforcement

Hybrid fiber reinforced concrete (HFRC) is based on a multilevel-reinforcement material design that improves both the compressive strength and tensile strength. Investigations of the mechanical performance of HFRC with two types of steel fibers were conducted experimentally. The investigated parameters were the volume fractions of the short steel fibers and long steel fibers. The compressive strength, tensile strength, and flexural strength of the HFRC were researched. The group with volume fractions of 1.5% for the long steel fibers and 0.5% for the short steel fibers exhibited the best flexural strength. The synergetic effect clearly was improved by combining different types of steel fiber. Four HFRC deep beams and one reinforced concrete (RC) deep beam were conducted to consider the shear behavior of these beams. The primary variables included the volume fraction of steel fibers and the web reinforcement ratio. The shear behavior was evaluated based on the cracking pattern, load-deflection behavior, and shear capacity. All of the beams failed due to the formation of diagonal cracks. The results indicated that hybrid fibers contribute greatly to the shear behavior of deep beams. The hybrid fibers led to the formation of multiple diagonal cracks in the deep beams and enhanced the damage tolerance. With the same web reinforcement ratio, the ultimate load and deformation of the HFRC deep beams were better than those of the RC deep beam.

scholarly journals Children’s Astronomy. Development of the Shape of the Earth Concept in Polish Children between 5 and 10 Years of Age

2021 ◽  
Vol 11 (2) ◽  
pp. 75
Author(s):  
Jan Amos Jelinek
Keyword(s):  
Mental Model ◽  
Cultural Influences ◽  
Test Results ◽  
The Earth ◽  
Spherical Earth ◽  
The Individual ◽  
High Level ◽  
Cognitive Problems ◽  
Teaching Situations ◽  
Model Approach

The Earth’s shape concept develops as consecutive cognitive problems (e.g., the location of people and trees on the spherical Earth) are gradually resolved. Establishing the order of problem solving may be important for the organisation of teaching situations. This study attempted to determine the sequence of problems to be resolved based on tasks included in the EARTH2 test. The study covered a group of 444 children between 5 and 10 years of age. It captured the order in which children solve cognitive problems on the way to constructing a science-like concept. The test results were compared with previous studies. The importance of cultural influences connected to significant differences (24%) in test results was emphasised. Attention was drawn to the problem of the consistency of the mental model approach highlighted in the literature. The analysis of the individual sets of answers provided a high level of consistency of indications referring to the same model (36%), emphasising the importance of the concept of mental models.

scholarly journals Random Material Property Fields of 3D Concrete Microstructures Based on CT Image Reconstruction

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1423
Author(s):  
George Stefanou ◽  
Dimitrios Savvas ◽  
Panagiotis Metsis
Keyword(s):  
Random Fields ◽  
Volume Fraction ◽  
Concrete Specimen ◽  
Elasticity Tensor ◽  
Statistical Characteristics ◽  
Moving Window ◽  
Window Method ◽  
Ct Image Reconstruction ◽  
Random Material Property ◽  
Spatially Varying

The purpose of this paper is to determine the random spatially varying elastic properties of concrete at various scales taking into account its highly heterogeneous microstructure. The reconstruction of concrete microstructure is based on computed tomography (CT) images of a cubic concrete specimen. The variability of the local volume fraction of the constituents (pores, cement paste and aggregates) is quantified and mesoscale random fields of the elasticity tensor are computed from a number of statistical volume elements obtained by applying the moving window method on the specimen along with computational homogenization. Based on the statistical characteristics of the mesoscale random fields, it is possible to assess the effect of randomness in microstructure on the mechanical behavior of concrete.

scholarly journals Experimental and Numerical Investigation on the Steel Reinforced Grout (SRG) Composite-to-Concrete Bond

2020 ◽  
Vol 4 (4) ◽  
pp. 182
Author(s):  
Luciano Ombres ◽  
Salvatore Verre
Keyword(s):  
Bond Length ◽  
Failure Modes ◽  
Peak Load ◽  
Element Model ◽  
Test Results ◽  
Shear Tests ◽  
Bond Slip ◽  
Bond Behavior ◽  
Direct Shear Tests ◽  
Inorganic Matrix

In the paper, the bond between a composite strengthening system consisting of steel textiles embedded into an inorganic matrix (steel reinforced grout, SRG) and the concrete substrate, is investigated. An experimental investigation was carried out on medium density SRG specimens; direct shear tests were conducted on 20 specimens to analyze the effect of the bond length, and the age of the composite strip on the SRG-to-concrete bond behavior. In particular, the tests were conducted considering five bond length (100, 200, 250, 330, and 450 mm), and the composite strip’s age 14th, 21st, and 28th day after the bonding. Test results in the form of peak load, failure modes and, bond-slip diagrams were presented and discussed. A finite element model developed through commercial software to replicate the behavior of SRG strips, is also proposed. The effectiveness of the proposed numerical model was validated by the comparison between its predictions and experimental results.

An Opinion on the Assessment of People Who May Have an Auditory Processing Disorder

2012 ◽  
Vol 23 (02) ◽  
pp. 097-105 ◽  
Author(s):  
Harvey Dillon ◽  
Sharon Cameron ◽  
Helen Glyde ◽  
Wayne Wilson ◽  
Dani Tomlin
Keyword(s):  
At Risk ◽  
Auditory Processing ◽  
Specific Form ◽  
Test Battery ◽  
Auditory Processing Disorder ◽  
Test Results ◽  
Hierarchical Approach ◽  
Clinical Efficiency ◽  
Impaired Ability ◽  
The Individual

We need to rethink how we assess auditory processing disorder (APD). The current use of test batteries, while necessary and well accepted, is at risk of failing as the size of these batteries increases. To counter the statistical, fatigue, and clinical efficiency problems of large test batteries, we propose a hierarchical approach to APD assessment. This begins with an overall test of listening difficulty in which performance is measurably affected for anyone with an impaired ability to understand speech in difficult listening conditions. It proceeds with a master test battery containing a small number of single tests, each of which assesses a different group of skills necessary for understanding speech in difficult listening conditions. It ends with a detailed test battery, where the individual tests administered from this battery are only those that differentiate the skills assessed by the failed test(s) from the master test battery, so that the specific form of APD can be diagnosed. An example of how hierarchical interpretation of test results could be performed is illustrated using the Listening in Spatialized Noise—Sentences test (LiSN-S). Although consideration of what abilities fall within the realm of auditory processing should remain an important issue for research, we argue that patients will be best served by focusing on whether they have difficulty understanding speech, identifying the specific characteristics of this difficulty, and specifically remediating and/or managing those characteristics.

scholarly journals A novel experimental method to characterise the shear strength of concrete based on pre-stressed samples. A comparison with existing techniques

2018 ◽  
Vol 183 ◽  
pp. 02049
Author(s):  
Pascal Forquin ◽  
Reem Abdul-Rahman ◽  
Dominique Saletti
Keyword(s):  
Experimental Method ◽  
Shear Fracture ◽  
Plain Concrete ◽  
Concrete Specimen ◽  
Compression Tests ◽  
Second Stage ◽  
Wide Range ◽  
Metallic Ring ◽  
Do So ◽  
Metallic Cell

Mode II shear fracture process can be observed in plain-concrete structures exposed to intensive loadings such as shock, blasting or projectile-impact. It is the reason why the quasi-static and dynamic shear fracturing properties of concrete need to be investigated. In previous works performed by Forquin and coauthors a passive confining cell was applied to PTS (Punch-Through-Shear) specimens in a similar way than in quasi-oedometric compression tests where metallic ring are used as passive confinement. However the change of confining level during the sample loading constitutes a main drawback of this technique. In the present work a novel testing method is proposed based on a pre-stressing of the sample. To do so, the concrete specimen is inserted into pre-stressed metallic cell. During the unloading stage confining stresses are transferred to the ligament of the sample. In a second stage, a differential displacement applied to the central part of the sample toward the side parts produces a shearing of the ligament. The experiments performed in static and dynamic conditions (SHPB testing) allow the shear response of concrete to be determined over a wide range of strain-rates. In the present communication, the testing technique and obtained results are compared to the obtained data with the previous experimental method.

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