scholarly journals Shear Strengthening of High Strength Concrete Beams That Contain Hooked-End Steel Fiber

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 17
Author(s):  
Hyun-Do Yun ◽  
Gwon-Young Jeong ◽  
Won-Chang Choi

Steel fiber has been used successfully in concrete mixtures to control volumetric changes, including shrinkage. However, the feasibility of the use of steel fiber has been restricted to nonstructural construction, such as ‘slab on ground’. Recently, researchers have attempted to expand the applications of steel fiber to replace structural reinforcement (rebar) and have shown promising results in its substitution for shear reinforcement. Few studies have been conducted to ensure the feasibility of using steel fiber in structural components, however. This experimental study was designed to investigate the shear performance of steel fiber-reinforced concrete beams using the tensile strength of steel fiber and the shear span-to-depth ratio as variables. The experimental results indicate that the tensile strength of steel fiber significantly affects the shear strength of steel fiber-reinforced concrete beams, regardless of the shear span-to-depth ratio, and that steel fiber can play a role in shear reinforcement of concrete beams.

Author(s):  
O. Radaikin ◽  
L. Sharafutdinov

The purpose of the study is to experimentally study the joint work of steel fiber reinforced concrete (SFB) reinforcement jacket and reinforced concrete beams at all stages of loading to further develop a methodology for calculating this method of reinforcing bending elements. The main results of the study consist in assessing the strength, stiffness, fracture toughness, as well as the nature of fracture with a picture of the development of cracks for the examined 4 samples (two with a jacket of reinforcement, two - control - without reinforcement). It has been established that the use of SFB jacket with a thickness of 45 mm and with a fiber content percentage of 2,5% (at a flow rate of 196 kg/m3) increases the breaking load by 20 %, stiffness from 3,4 to 11 times as it is loaded, crack resistance 2,4-2,8 times. The results are compared with computer modeling in ANSYS PC: the discrepancy in the load of crack formation, fracture and deflection values for full-scale samples and a computer model are within 6,3 %, which indicates the reliability of the numerical results and the possibility of using the proposed computer models in further studies on topic of the article.


Author(s):  
Natalia Sharma

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.


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