Influence of Fiber Content on Shear Capacity of Steel Fiber-Reinforced Concrete Beams

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 she...

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Bibliographic Details
Published in:Fibers 2019-12, Vol.7 (12), p.102
Main Authors: Torres, Juan Andres, Lantsoght, Eva O.L.
Format: Article
Language:English
Subjects:
Aggregates
Building codes
Compressive strength
Concrete
Concrete construction
Concrete structures
Construction industry
Ductility
Experiments
Failure modes
Fiber volume fraction
Geometry
Low carbon steels
Reinforced concrete
Reinforcement
Reinforcing steels
Shear
Shear strength
Steel fiber reinforced concretes
Steel fibers
Stirrups
Structural members
Tensile strength
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Summary: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.
ISSN:2079-6439
2079-6439
DOI:10.3390/fib7120102