Exploring the Effect of Varying Fiber Dosages as Stirrup Substitutes in Torsion-Loaded Concrete Beams

Abstract

Over the past few decades, numerous studies have explored the use of steel fiber (SF) as an alternative to transverse reinforcement rebars in reinforced concrete beams, either partially or completely replacing them. However, there are limited studies that have investigated the effect of fiber dosage and length on reinforced concrete beam performance under torsional loads without the use of transverse reinforcement rebars. In this study, experimental investigations were conducted to examine the performance of reinforced SF concrete beams subjected to torsional load, utilizing SFs as a complete substitution of transverse reinforcement rebars. Ten different concrete mixes with varying dosages of SFs, namely 0%, 0.5%, 1.0%, and 1.5%, were examined while maintaining the same aspect ratio for fiber length and diameter. The results revealed that the addition of SFs in the concrete mix had an impact on its properties, reducing workability but increasing flexural, tensile, and compressive strengths. By incorporating 1.0% of SFs in the concrete mix, the missing torsional strength resulting from the absence of stirrups was adequately compensated. Moreover, the presence of SFs significantly influenced the ductile behavior beyond the point of cracking in the tested beams. Hence, it is recommended that SFs are incorporated with dosages of 1.0% and 1.5% in the concrete mixture, particularly for beams subjected to torsion, as a viable substitute for stirrups.

Research on Lateral Resistance Performance of Prestressed Cross-Laminated Timber–Concrete Composite Structures under Reciprocating Loads

“…This phenomenon was attributed to the absence of stirrups in these areas, which led to a weak overall tensile capacity. The uneven terrain at the testing site further contributed to this cracking [ 19 ].…”

Flexural Behavior of Inverted Steel Fiber-Reinforced Concrete T-Beams Reinforced with High-Yield Steel Bars

“…Muna et al found that steel fibers have a significant impact on the flexural, tensile, and compressive strength of concrete beams according to investigations into the torsional performance of beams reinforced with different volumes of steel fiber. Furthermore, a volume content of 1.0% steel fibers can fully compensate for the decreased torsional strength in beams due to the absence of stirrups [23]. The advantages of this newly developed concrete have already been identified by many civil engineers and researchers [18,19,24].…”

“…Nevertheless, shear or torsional strength cannot be significantly improved with high-strength bars alone. SFRC mainly increases shear and torsional capacity and the cracking moment of elements [6][7][8]23]. These materials can increase the overall performance of members, including the different aspects mentioned above, if jointly employed in concrete beams under complex loadings.…”

Analytic Investigation of Hooked Stirrups on Seismic Behavior of Reinforced Concrete 3D Frame Buildings

“…In order to obtain a comprehensive assessment of the seismic behavior of reinforced concrete structures, this study specifically focuses on the effect of two different types of stirrups, i.e., hooked and unhooked stirrups. Previous research has shown that hooked stirrups can improve energy dissipation and ductility by providing additional restraint to the concrete core, while unhooked stirrups, although widely used, may provide relatively limited benefits in this regard [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Rosso et al [19] estimated the effect of corrosion on the capacity and ductility in their study.…”