Evaluation of a minimum flexural reinforcement ratio using fracture-based modelling

Fayyad, Tahreer M.; Lees, Janet M.

doi:10.2749/222137815818357854

Cited by 6 publications

(6 citation statements)

References 12 publications

(7 reference statements)

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“…Minimum reinforcement has been studied in many publications. Some of these publications, however, are focused only on robustness reinforcement to avoid brittle failure from a very practical code‐type formulation, or on how robustness reinforcement can be optimized by consideration of fracture mechanics, and its implications on the size effect, and are mostly centered on bending without axial force . Others are focused on minimum reinforcement required for control of cracking, but these either address cases of pure bending or pure axial forces but not the combination of both or deal only with cracking from imposed strains …”

Section: Introductionmentioning

confidence: 99%

Minimum reinforcement revisited

Caldentey

García

Peiretti

2018

Structural Concrete

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Minimum reinforcement has a significant impact on the economy and sustainability of concrete structures. Current code formulations do not always address all practical cases, in particular the amount of minimum reinforcement required in thick members, for which codes generally over‐estimate the necessary values. Also, some codes have formulations which are only applicable to limited conditions, or, as is the case of Eurocode 2, have a general formulation, which, however, is not easy to understand, is not complete, and still over‐estimates the necessary reinforcement. In the light of the revision of Eurocode 2, this paper proposes a general formulation for general cross sections formed by a combination of rectangles (rectangular, flanged, or box sections) subjected to both bending and axial force based on mechanical principles and provides a reduction in minimum reinforcement for thick members by allowing the formation of larger interior cracks while providing adequate control of surface cracks.

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Section: Introductionmentioning

confidence: 99%

Minimum reinforcement revisited

Caldentey

García

Peiretti

2018

Structural Concrete

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“…gives more ductile behaviour when compared with beams with lower reinforcement ratios (Fayyad and Lees 2015). However, this increase in the ductility was not sufficient to ensure a final ductile failure and the beam failed due to a sudden reinforcement fracture.…”

Section: Model Outcomementioning

confidence: 97%

“…Fracture processes are particularly important for lightly reinforced concrete beams where the crack propagation and concrete tensile softening have a strong influence on the behaviour. An understanding of these phenomena will also inform a more fundamental definition of the minimum reinforcement requirements for reinforced concrete beams (Fayyad and Lees 2015…”

Section: Research Significance and Motivationmentioning

confidence: 99%

Integrated Fracture-Based Model Formulation for RC Crack Analysis

Fayyad

Lees

2018

J. Struct. Eng.

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There is an opportunity to revisit and generalise classical theories for concrete cracking in light of increased interest in the use of non-conventional reinforcing materials and material efficiency. Fracture-based models to describe concrete cracking have potential but a limitation has been that many variables and different phenomena have to be incorporated to produce realistic material models. In this paper, an integrated fracture-based model (IFBM) is developed to predict the behaviour of lightly reinforced concrete beams. The proposed model is a closed-form solution that integrates different local phenomena to more precisely describe the onset of cracking, crack propagation and crack rotation. The IFBM incorporates post-cracking tensile stresses in the concrete, the bond-slip behaviour between the reinforcement and concrete, and compression softening in the concrete compressive zone. The model can predict parameters such as the crack length development and crack mouth opening displacement in Mode I lightly reinforced concrete flexural specimens subjected to three-point bending. The predictions show a fairly good agreement with experimental results for small-scale reinforced concrete beams with low reinforcement ratios (0.15-0.5%). The ability of the IFBM to identify specific failure modes and to capture the crack propagation and crack rotation stages of behaviour in lightly reinforced concrete beams are particular advantages. Such an approach provides a powerful tool to study the problem of minimum reinforcement requirements.

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“…If the failure of a hybrid GFRP/steel RC beam is controlled by the yielding of steel and rupturing of FRP, then a minimum amount of hybrid GFRP/steel reinforcement should be provided to prevent failure upon concrete cracking [24][25][26][27][28]:…”

Section: Minimum Hybrid Gfrp/steel Reinforcement Ratiomentioning

confidence: 99%

“…There are some approaches to develop formulas for determining the limiting reinforcement ratios for RC beams. The most popular methods are the fracture mechanics method and equilibrium equations method, which equate the cracking moment M cr to the flexural strength M u [24][25]. The latter method is used in existing standards and design codes.…”

Section: Introductionmentioning

confidence: 99%

Limiting Reinforcement Ratios for Hybrid GFRP/Steel Reinforced Concrete Beams

Nguyen

Dang

2021

Int. j. eng. technol. innov.

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In this work, a theoretical approach is proposed for estimating the minimum and maximum reinforcement ratios for hybrid glass fiber reinforced polymer (GFRP)/steel-reinforced concrete beams to prevent sudden and brittle failure as well as the compression failure of concrete before the tension failure of reinforcements. Equilibrium equations were used to develop a method for determining the minimum hybrid GFRP/steel reinforcement ratio. A method for determining the maximum hybrid GFRP/steel reinforcement ratio was also developed based on the equilibrium of forces of the balanced failure mode. For estimating the load-carrying capacity of concrete beams reinforced with hybrid GFRP/steel, less than the minimum and more than the maximum reinforcement ratio is recommended. Comparisons between the proposed expressions, experimental data, and available test results in the literature shows good agreement between the theoretical and experimental data, with a maximum discrepancy of 7%.

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Evaluation of a minimum flexural reinforcement ratio using fracture-based modelling

Cited by 6 publications

References 12 publications

Minimum reinforcement revisited

Minimum reinforcement revisited

Integrated Fracture-Based Model Formulation for RC Crack Analysis

Limiting Reinforcement Ratios for Hybrid GFRP/Steel Reinforced Concrete Beams

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