Improving the Failure Mode of Over-Reinforced Concrete Beams Using Strain-Hardening Cementitious Composites

Atta, A.A.; Khalil, Abd El-Hakim

doi:10.1061/(asce)cf.1943-5509.0000857

Cited by 15 publications

(8 citation statements)

References 11 publications

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“…This may be attributed to the good bond strength that was achieved between the surfaces of the SFRC and NC by using the casting procedure as explained in Section 2.4, in addition to the presence of stirrups in beams that work as effective shear connectors. 32 In contrast to the other composite beams, beam C1* in G5 failed by debonding between NC and SFRC layers in the compression zone. In this failure, the SFRC layer in the compression zone was not crushed, indicating that the high compressive strain capacity of SFRC has not been fully used.…”

Section: Crack Pattern and Modes Of Failurementioning

confidence: 92%

The effect of using steel fibers reinforced concrete layer in compression zone on the flexural behavior of over‐reinforced concrete beams

Duhaim,

Mashrei

2023

Structural Concrete

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Ductility is one of the most important requirements of RC design besides other requirements such as strength and stiffness. In recent years, concrete beams with a large amount of tensile reinforcement ratio (ρ) have been required in large projects, such as high‐rise buildings and bridges. Using high (ρ) increases the strength and stiffness of the beams and leads to a decrease the ductility. This paper aimed to investigate the effect of using steel fibers reinforced concrete (SFRC) layer in compression zone on the flexural behavior of over‐reinforced concrete beams. Partial replacement of concrete with SFRC layer in compression zone was used to avoid the brittle compression failure of concrete. For this purpose, 12 over‐reinforced concrete beams with a span of 1300 mm and a cross‐section of 120 mm × 180 mm were cast and tested under a three‐point loading. The first beam was used as a reference beam and others as strengthened beams using SFRC layer. The effects of thickness and length of strengthening layer, (ρ), volume fractions of steel fibers, and strengthening methods on flexural performance of tested beams were investigated. The flexural capacity, failure modes, crack patterns, load–deflection relationships, load–strain relationships, ductility index, and toughness were evaluated. The results showed that the suggested technique (SFRC layer in the compression zone) is an effective technique to increase ultimate load, ductility, and toughness by up to 35.72%, 121.01%, and 349.16%, respectively, compared to the reference beam. Furthermore, the failure mode changed from brittle to ductile failure. Also, one of the main advantages of this technique is allows to increase of (ρ) up to 8.55% (4.15ρb) without needing the compressive reinforcement. The results of this study indicate that the using SFRC layer in the compression zone is an appropriate and economical method to provide high flexural capacity and ductility over‐reinforced concrete beams.

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Section: Crack Pattern and Modes Of Failurementioning

confidence: 92%

The effect of using steel fibers reinforced concrete layer in compression zone on the flexural behavior of over‐reinforced concrete beams

Duhaim,

Mashrei

2023

Structural Concrete

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“…This can be attributed to the fact that good bond strength is achieved between the surfaces of the ductile material and NC, in addition to the presence of stirrups in beams that work as effective shear connectors (Atta & Khalil, 2016).…”

Section: Crack Pattern and Modes Of Failurementioning

confidence: 99%

Stress–strain relationship of ductile materials and flexural behavior of ductile over-reinforced concrete beams

DUHAIM¹,

MASHREI²

2022

srees

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This paper aimed to investigate the effect of using ductile materials in the compression zone on the flexural performance of over-reinforced concrete beams. In order to avoid brittle compression failure, partial replacement of concrete with ductile materials layer in the compression zone was used. Four over-reinforced concrete beams of size 120 × 180 × 1,300 mm were cast and tested under three-point loading conditions. The steel fibers reinforced concrete (SFRC), slurry infiltrated fiber concrete (SIFCON), and ultra-high performance fiber reinforced concrete (UHPFRC) were used as ductile materials. The flexural capacity of the beams, failure modes, crack patterns, load-deflection relationships, ductility index, and toughness were investigated. The results showed that using ductile materials in the compression zone is an effective technique to increase the ultimate load, ductility, and toughness by up to 52.46, 84.78 and 279.93%, respectively, compared to the reference beam. In addition, the failure mode changed from brittle to ductile failure. Noting that the use of SFRC layer enhanced the ductility of over-reinforced concrete beams more than using UHPFRC and SIFCON layers. Also, one of the main advantages of this technique is led to increase the tensile reinforcement ratio up to 8.548% without needing the compressive reinforcement. Thus, ductile composite beams with a high flexural capacity were generated using an economical amount of ductile materials.

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“…The strain-hardening effect of the tensile rebar obtained by the high bond strength of HPFRCC improved the RC beams patched with HPFRCC. Moreover, Atta and Khalil (2016) utilized the strain-hardening cementitious composites (SHCC) in enhancing the failure mode of over-reinforced concrete beams. The SHCC characterized by exhibiting tensile hardening behavior up to several percent strain is accompanied by the formation of fine multiple cracks.…”

Section: Introductionmentioning

confidence: 99%

Using high-performance cementitious mortar and external prestressing for retrofitting of corroded reinforced concrete beams

Atta

Taman

2020

Advances in Structural Engineering

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The effect of using high-performance polypropylene fiber–reinforced cementitious mortar on reinforced concrete beam repair was presented in this article. Results of an experimental study for the flexural performance of 13 reinforced concrete beams were presented. The corrosion level, in terms of the mass loss of steel, was estimated to be 10% and 15%. Three non-strengthened specimens were tested as a reference: one control uncorroded specimen and two control specimens corroded with 10% and 15%. Ten specimens were strengthened using different techniques; replacement of the spilled concrete at the tension zone with 40-mm-thick high-performance polypropylene fiber–reinforced cementitious mortar, using external prestressing bars at the tension zone with adding 20-mm-thick high-performance polypropylene fiber–reinforced cementitious mortar at the compression zone, and a combination of these techniques. The prestressing reinforcing bars stress was chosen to be 0.25 fpy and 0.38 fpy for the corroded 10% specimens and 0.25 fpy for the corroded 15% specimens. A combination of 40-mm-thick high-performance polypropylene fiber–reinforced cementitious mortar at the tension side and external prestressing bars at the tension zone increased the specimen capacity by 15% and 34% compared with the uncorroded and 10% corroded control specimens, respectively. A comparative study was conducted to evaluate the efficiency of various strengthening techniques. An analytical model was proposed in order to give design guidelines.

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Improving the Failure Mode of Over-Reinforced Concrete Beams Using Strain-Hardening Cementitious Composites

Cited by 15 publications

References 11 publications

The effect of using steel fibers reinforced concrete layer in compression zone on the flexural behavior of over‐reinforced concrete beams

The effect of using steel fibers reinforced concrete layer in compression zone on the flexural behavior of over‐reinforced concrete beams

Stress–strain relationship of ductile materials and flexural behavior of ductile over-reinforced concrete beams

Using high-performance cementitious mortar and external prestressing for retrofitting of corroded reinforced concrete beams

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