Structural performance of steel fibre reinforced concrete — Part IV. Toughness properties

2014 ◽  
Vol 5 (2) ◽  
pp. 119-125
Author(s):  
I. Kovács

The present paper of a series deals with the experimental characterisation of flexural toughness properties of structural concrete containing different volume of hooked-end steel fibre reinforcement (75 kg/m3, 150 kg/m3). Third-point flexural tests were carried out on steel fibre reinforced concrete beams having a cross-section of 80 mm × 85 mm with the span of 765 mm, hence the shear span to depth ratio was 3. Beams were sawn out of steel fibre reinforced slab elements (see Part I) in order to take into consideration the introduced privilege fibre orientation (I and II) and the position of the beam (Ba-a, Ba-b, Ba-c) before sawing (see Part I). Flexural toughness properties were determined considering different standard specifications, namely the method of the ASTM (American Standards for Testing Materials), the process of the JSCE (Japan Society of Civil Engineering), and the final proposal of Banthia and Trottier for the post cracking strength. Consequently, behaviour of steel fibre reinforced concrete was examined in bending taking into consideration different experimental parameters such as fibre content, concrete mix proportions, fibre orientation, positions of test specimens in the formwork, while experimental constants were the size of specimens, the type of fibre used and the test set-up and test arrangement.

2014 ◽  
Vol 5 (1) ◽  
pp. 21-33
Author(s):  
I. Kovács

Abstract The present paper of a series deals with the experimental characterisation of compressive strength and compressive behaviour (stress-strain relationship) of different structural concrete containing different volume of steel fibre reinforcement (0 V%, 0.5V%, 1.0V%, 75 kg/m3, 150 kg/m3) and different configuration of steel fibres (crimped, hooked-end). Compressive tests were carried out on standard cube (150 mm × 150 mm × 150 mm) and cylinder (Ø = 150 mm, l = 300 mm) specimens considering random fibre orientation. Since the fibre orientation may significantly affect the compressive behaviour, test series were also performed on cylinders (Ø = 70 mm, l = 100 mm) drilled out of fibre reinforced concrete beams and prisms (100 mm × 100 mm × 240 mm) sawn out of steel fibre reinforced deep beams. Throughout the tests stress-strain relationships were registered on the standard cube and cylinder specimens as well. In conclusion, behaviour of steel fibre reinforced concrete was examined in compression taking into consideration different experimental parameters such as fibre content, type of fibres, fibre configuration, fibre orientation, size of specimens (size effect) and concrete mixture.


2014 ◽  
Vol 5 (2) ◽  
pp. 105-117
Author(s):  
I. Kovács

The present paper of a series deals with the experimental characterisation of tensile splitting strength and compressive behaviour of different structural concrete containing different volume of steel fibre reinforcement (0 V%, 0.5 V%, 1.0 V%, 75 kg/m3, 150 kg/m3) and different configuration of steel fibres (crimped, hooked-end). Tensile splitting tests were carried out on standard cylinder (∅ = 150 mm, l = 300 mm) specimens (so-called Brazilian test) considering random fibre orientation. Since the fibre orientation may significantly affect the tensile behaviour test series were also performed on cross-section (100 mm × 100 mm) of steel fibre reinforced concrete beams (100 mm × 100 mm × 240 mm) sawn out of steel fibre reinforced slab elements. Taken as a whole behaviour of steel fibre reinforced concrete was examined in tension taking into consideration different experimental parameters such as fibre content, type of fibres, fibre configuration, fibre orientation, size of specimens (size effect) and concrete mixture.


2014 ◽  
Vol 5 (1) ◽  
pp. 9-19
Author(s):  
I. Kovács

Abstract The papers of the series deal with experimental characterisation of mechanical as well as structural properties of different steel fibre reinforced concretes that can be used for several structural applications. An extensive experimental programme (six years) has been developed to investigate the effect of steel fibre reinforcement on the mechanical performance and structural behaviour of concrete specimens. Specimens and test methods were selected to be able to detect realistic behaviour of the material, representing clear effect on the structural performance. Material compositions, test methods, type of test specimens will be detailed in the presented paper (Part I). Furthermore, compressive strength (Part II), stress-strain relationship (Part II), splitting strength (Part III) and toughness (Part IV) will also be discussed. In the light of the motivation to determine the structural performances of 1D concrete structural element affected by steel fibre reinforcement, bending and shear behaviour (Part V) as well as serviceability state (Part VI) of steel fibre reinforced concrete beams will be analysed. Since normal force — prestressing force — can affectively be used to improve the structural performances of RC element flexural tests were carried out on prestressed pretensioned steel fibre reinforced concrete beams (Part VII). Moreover, focusing on the in-plane state of stresses for 2D structures, behaviour of steel fibre reinforced concrete deep beams in shear and steel fibre reinforced concrete slabs (Part VIII) in bending will be explained. Finally, based on the wide range of the experimental and analytical studies on the presented field, a new material model for the 1D uniaxial behaviour (Part IX) and its possible extension to the 3D case (Part X) will be described hereafter. All papers will put emphasis on the short literature review of the last four decades.


2018 ◽  
Vol 15 (1) ◽  
pp. 15
Author(s):  
AMIR SYAFIQ SAMSUDIN ◽  
MOHD HISBANY MOHD HASHIM ◽  
SITI HAWA HAMZAH ◽  
AFIDAH ABU BAKAR

Nowadays, demands in the application of fibre in concrete increase gradually as an engineering material. Rapid cost increment of material causes the increase in demand of new technology that provides safe, efficient and economical design for the present and future application. The introduction of ribbed slab reduces concrete materials and thus the cost, but the strength of the structure also reduces due to the reducing of material. Steel fibre reinforced concrete (SFRC) has the ability to maintain a part of its tensile strength prior to crack in order to resist more loading compared to conventional concrete. Meanwhile, the ribbed slab can help in material reduction. This research investigated on the bending strength of 2-ribbed and 3-ribbed concrete slab with steel fibre reinforcement under static loading with a span of 1500 mm and 1000 mm x 75 mm in cross section. An amount of 40 kg/m steel fibre of all total concrete volume was used as reinforcement instead of conventional bars with concrete grade 30 N/mm2. The slab was tested under three-point bending. Load versus deflection curve was plotted to illustrate the result and to compare the deflection between control and ribbed slab. This research shows that SFRC Ribbed Slab capable to withstand the same amount of load as normal slab structure, although the concrete volume reduces up to 20%.


2021 ◽  
Vol 15 (1) ◽  
pp. 81-92
Author(s):  
Constantinos B. Demakos ◽  
Constantinos C. Repapis ◽  
Dimitros P. Drivas

Aims: The aim of this paper is to investigate the influence of the volume fraction of fibres, the depth of the beam and the shear span-to-depth ratio on the shear strength of steel fibre reinforced concrete beams. Background: Concrete is a material widely used in structures, as it has high compressive strength and stiffness with low cost manufacturing. However, it presents low tensile strength and ductility. Therefore, through years various materials have been embedded inside it to improve its properties, one of which is steel fibres. Steel fibre reinforced concrete presents improved flexural, tensile, shear and torsional strength and post-cracking ductility. Objective: A better understanding of the shear performance of SFRC could lead to improved behaviour and higher safety of structures subject to high shear forces. Therefore, the influence of steel fibres on shear strength of reinforced concrete beams without transverse reinforcement is experimentally investigated. Methods: Eighteen concrete beams were constructed for this purpose and tested under monotonic four-point bending, six of which were made of plain concrete and twelve of SFRC. Two different aspect ratios of beams, steel fibres volume fractions and shear span-to-depth ratios were selected. Results: During the experimental tests, the ultimate loading, deformation at the mid-span, propagation of cracks and failure mode were detected. From the tests, it was shown that SFRC beams with high volume fractions of fibres exhibited an increased shear capacity. Conclusion: The addition of steel fibres resulted in a slight increase of the compressive strength and a significant increase in the tensile strength of concrete and shear resistance capacity of the beam. Moreover, these beams exhibit a more ductile behaviour. Empirical relations predicting the shear strength capacity of fibre reinforced concrete beams were revised and applied successfully to verify the experimental results obtained in this study.


2017 ◽  
Vol 23 (6) ◽  
pp. 806-813 ◽  
Author(s):  
Inmaculada MARTÍNEZ-PÉREZ ◽  
Juozas VALIVONIS ◽  
Remigijus ŠALNA ◽  
Alfonso COBO-ESCAMILLA

The building of structures from steel fibre reinforced concrete (SFRC) in the external and conventional rein­forced concrete (RC) in the internal layer represents an economical alternative of structures effectively using SFRC. The paper presents test results of flexural behaviour of layered beams with SFRC external layers and RC internal layer. The behaviour of these beams is compared to test results of SFRC and conventional RC beams. The test results show, that the flexural load capacity for all series of beams is nearly similar, but the deflections of layered beams are less comparing to monolithic ones. It also been shown that the equations indicated in the Eurocode 2 can be used to design the flexural reinforcement in layered SFRC beams.


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