Determination of the first-crack strength and flexural toughness of steel fiber-reinforced concrete

Mindess, Sidney; Chen, L.; Morgan, D. R.

doi:10.1016/1065-7355(94)90025-6

Cited by 49 publications

(22 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Os resultados estão apresentados na Tabela 6. Chama a atenção o nível muito baixo de variação dos resultados, que ficaram bem abaixo dos 30 % de coeficiente de variação apresentados pela literatura como esperados para este tipo de ensaio [31].…”

Section: Figura 3: Curvas Médias De Carga Por Deslocamento Vertical Ounclassified

Análise comparativa de comportamento mecânico de concreto reforçado com macrofibra polimérica e com fibra de aço

Salvador

Figueiredo

2013

Matéria (Rio J.)

View full text Add to dashboard Cite

A utilização de macrofibras poliméricas está amplamente difundida no mercado brasileiro. Entretanto, a caracterização do comportamento mecânico de concretos reforçados com essas macrofibras ainda deve ser mais bem avaliada. Dentre os diversos métodos utilizados para essa finalidade, os ensaios realizados com sistema fechado de controle de velocidade de deslocamento fornecem resultados mais confiáveis. A principal vantagem conferida por esse sistema está na avaliação desses compósitos em baixo nível de fissuração, com maior nível de acurácia. O desempenho desses compósitos foi estudado segundo uma norma recente (ASTM C1609 - 2010) e outra que é uma referência tradicional no Brasil (JSCE-SF4 - 1984). Ambos os procedimentos prescrevem ensaios de flexão de corpos-de-prova prismáticos para determinação da resistência residual pós-fissuração e da tenacidade. Foram estudadas duas fibras: uma macrofibra de polipropileno, nas dosagens de 0,22, 0,33, 0,50, 0,66, 0,82 e 1,0% em volume, e outra de aço, nas dosagens de 0,19, 0,32 e 0,45% em volume. Foi utilizada uma matriz de concreto com resistência média à compressão de 35MPa. Foi verificado que a macrofibra polimérica pode proporcionar o mesmo nível de resistência residual que a fibra de aço, desde que sejam determinados teores com equivalência de desempenho em estudo de dosagem. Além disso, foi comprovada a maior precisão do ensaio utilizando-se a velocidade de deslocamento do corpo-de-prova como parâmetro de controle do ensaio, devido à redução da instabilidade pós-pico, que propiciou melhor avaliação da resistência residual do compósito nos níveis iniciais de deslocamento e fissuração da matriz.

show abstract

Section: Figura 3: Curvas Médias De Carga Por Deslocamento Vertical Ounclassified

Análise comparativa de comportamento mecânico de concreto reforçado com macrofibra polimérica e com fibra de aço

Salvador

Figueiredo

2013

Matéria (Rio J.)

View full text Add to dashboard Cite

show abstract

“…For fibered concrete, however, the gap between first-crack loads and peak loads leads the primary cracks to random and asymmetrical distribution beyond the pure flexural range. The diverse distribution of primary cracks greatly affects the toughness characterization [18][19][20][24][25][26][27][28] . This adversely affects obtaining an objective toughness index.…”

Section: Testing and Measuring Programsmentioning

confidence: 99%

“…However, it was found that an objective toughness index was greatly affected by many factors including the determination of first-crack loads (or deformations), prescribed deformation limits, material brittleness, specimen sizes, aggregate sizes, fiber types, asymmetry cracks and measuring techniques. Difference in the indices based on varied programs and measurements could be up to 200% or even more [17][18][19][20][21][22][23][24][25][26][27][28] . Dependence on varied factors makes establishing an objective engineering-applicable toughness index extremely difficult.…”

Section: Introductionmentioning

confidence: 99%

“…Another arises from the influence of loading patterns (e.g., three-point loading or four-point loading), control modes (e.g., displacement-control or loadcontrol, loading speeds, etc. ), fiber geometry or types, specimen sizes and material brittleness on measurements [17][18][19][20][21][22][23][24][25][26][27][28] . The critical concern is how to determine the first-crack deformation, i.e., the initial reference, for toughness characterization with consideration of various categories to which the fibered concrete belongs.…”

Section: Introductionmentioning

confidence: 99%

“…For this purpose, a number of testing and characterization methods were proposed to determine the energy absorption capability and toughness of fibered concrete, including compression, tension and bending tests [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] . The bending test program was adopted extensively for its easy operation and good similarity to engineering conditions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Toughness and characterization of reactive powder concrete with ultra-high strength

Liu

Chen

et al. 2009

Sci. China Ser. E-Technol. Sci.

View full text Add to dashboard Cite

A number of three-point bending and fracture tests of 200 MPa-level reactive powder concrete (RPC) with the various fiber contents have been conducted to probe the nature and characteristics of toughness of RPC200. The contribution of the embedded fibers to improving the crack-resistant capacity, energy absorption capacity and toughness with various deformation mechanisms has been analyzed. Taking account of that the first-crack deformation, peak-load deformation and their improvement varied with the fiber contents and that the deformation mechanism affected differently the performance at the first crack and the peak load, we took the peak-load deformation of plain RPC200 as the reference deformation to measure the toughness of fibered RPC200. Two toughness indices T 2(n−1) (n) and FT 2(n−1) (n) have been formulated based on P-δ responses and P-CMOD responses. The indices quantify the toughness of RPC200 with the various deformation mechanisms relative to perfectly elastoplastic materials by setting the toughness level 2(n−1) as the initial reference. It is shown that the toughness index T 2(n−1) (n) reflects the function of fibers to improve the toughness of RPC with the deformation throughout specimens, but overestimates the contribution to enhancing the toughness in post-peak periods. It underestimates, on other hands, the contribution to improving the toughness in the period from the first crack to the peak load. In contrast, the toughness index FT 2(n−1) (n) properly presents the capability that fibers absorb energy and constrain crack propagation in the matrix when the deformation is concentrated on the open crack. The proposed index unveils the contribution of fibers to toughening RPC200 both in the period from the first-crack to the peak load and in the period of post peak. This characterization method not only reveals the nature of toughness but also levels the toughness of RPC200. It could provide a way to establish an objective toughness characterization for RPC200 and facilitate its applications. reactive powder concrete, toughness, characterization index, deformation mechanism, flexure, fracture

show abstract

Residual flexural strengths of steel fiber reinforced concrete with multiple hooked‐end fibers

Venkateshwaran

Tan

2017

Structural Concrete

View full text Add to dashboard Cite

This paper presents the results of 3-point bending tests on 69 prenotched steel fiber reinforced concrete (SFRC) prisms conducted in accordance with EN 14651 to obtain the stress versus crack-mouth-opening displacement curves. SFRC prisms with fiber content greater than 20 kg/m 3 and containing multiple hooked-end fibers were found to exhibit deflection hardening behavior in bending after first crack. Based on the test results, empirical models to determine the residual flexural stresses are established through multiple regression analysis and further validated with test results available in the literature. The residual flexural strengths were found to be proportional to the reinforcing index, the square root of concrete compressive strength, and the square of the number of hooks at the fiber ends. Size effect is accounted for by introducing a factor which is a function of the fiber length. The empirical equations for the residual flexural strengths enable the use of Model Code 2010 constitutive relation for SFRC in tension without resorting to prism tests.hooked-end fibers, limit of proportionality, reinforcing index, residual flexural strengths, steel fiber reinforced concreteIn the early development, short discrete steel fibers have been used mainly for crack and shrinkage control in concrete members. 1 Studies have also showed that steel fibers significantly enhance the tensile and flexural strength of concrete. [2][3][4][5][6] The mechanical properties of steel fiber reinforced concrete (SFRC) are governed by the compressive strength of the matrix and the fiber reinforcing index (RI), defined as the product of volume fraction and aspect ratio of fibers. [6][7][8][9] Several types of steel fibers are available in the market. They include straight, crimped, twisted, and hooked-end steel fibers. Four-point bending tests on SFRC beams have indicated that hooked-end fibers provide higher flexural strength and toughness compared to wavy fibers. 10 This, in addition to workability issues with twisted fibers, has led to the popularity of hooked-end steel fibers in applications such as slab-on-piles and slab-on-grade systems. 11 Latest developments in the steel fiber industry have led to the manufacture of fibers with multiple hook-ends, that is, fibers having single, 1.5, and double hook-ends. 12 These fibers possess greater anchorage and stress transfer capability, and are expected to enhance the flexural performance of SFRC members.In order to predict the flexural capacity of SFRC elements, constitutive relations of SFRC in tension is essential and several models had been proposed. [13][14][15][16][17][18] The tensile stress distribution across a SFRC section at ultimate limit state is related to the residual (post-crack) flexural strength. According to EN, RILEM, and American Standard for Testing Materials (ASTM) test standards, 18-21 the residual flexural strength of SFRC is determined from the stress versus crack-mouth-opening displacement (CMOD) or stress versus deflection curves obtained from 3-point or 4-poi...

show abstract

Determination of the first-crack strength and flexural toughness of steel fiber-reinforced concrete

Cited by 49 publications

References 3 publications

Análise comparativa de comportamento mecânico de concreto reforçado com macrofibra polimérica e com fibra de aço

Análise comparativa de comportamento mecânico de concreto reforçado com macrofibra polimérica e com fibra de aço

Toughness and characterization of reactive powder concrete with ultra-high strength

Residual flexural strengths of steel fiber reinforced concrete with multiple hooked‐end fibers

Contact Info

Product

Resources

About