Determination of double- K fracture parameters of concrete using peak load method

Kumar, Shailendra; Pandey, Shashank; Srivastava, Ashok

doi:10.1016/j.engfracmech.2014.09.004

Cited by 30 publications

(31 citation statements)

References 33 publications

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“…The initial fracture toughness K ini is defined as the SIF at the crack tip when the external load reaches the initial cracking load . To date, several methods for determining the P ini or K ini of plain concrete have been proposed . Existing studies on three‐point bending tests and compact tension wedge splitting specimens have shown that K ini is hardly affected by specimen size .…”

Section: Introductionmentioning

confidence: 99%

Toughness enhancement and equivalent initial fracture toughness of cementitious composite reinforced with aligned steel fibres

Qing

Cheng

2019

Fatigue Fract Eng Mat Struct

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Based on theoretical analysis and numerical simulation, the impact of steel fibres on the stress intensity factor (SIF) at the crack tip for cementitious composite was studied. The enhanced toughness of steel fibre reinforced cementitious composite (SFRC) in resisting cracks was explained by the decrement of SIF caused by steel fibre inclusions at the crack tip of the composite. The equivalent initial fracture toughness Kme was used to characterize the crack initiation of SFRC. A simplified method for determining the Kme of SFRC was proposed based on a linear regression method. Fracture tests were conducted on three‐point bending notched beams with different steel fibre volume fractions and specimen sizes to study the crack initiation behaviour of aligned steel fibre reinforced cementitious composite (ASFRC). Kme of ASFRC was calculated, and the size effect of Kme was analysed. The results showed that Kme slightly increased with the steel fibre volume fraction and gradually became stable. For the tested specimens, whose heights varied between 40 and 100 mm, the specimen size had little impact on the Kme.

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Section: Introductionmentioning

confidence: 99%

Toughness enhancement and equivalent initial fracture toughness of cementitious composite reinforced with aligned steel fibres

Qing

Cheng

2019

Fatigue Fract Eng Mat Struct

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“…Extensive numerical and experimental investigations have been carried out using double‐K fracture parameters of concrete . From the various studies carried out earlier, it can be noted that there are a lot of complexities involved in computation for determining the double‐K fracture parameters of concrete, and no simple equations are available in the literature to date for computing these fracture parameters for the 3‐point bending test.…”

Section: Introductionmentioning

confidence: 99%

Simplified equations for determining double‐K fracture parameters of concrete for 3‐point bending test

Choubey

Kumar

2018

Fatigue Fract Eng Mat Struct

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The paper presents simplified polynomial equations for determining the double‐K fracture parameters of concrete for 3‐point bending beams with variable strengths and material properties of concrete. The derived equations avoid complexities involved in computations of fracture parameters using existing analytical methods. The input data required for systematic computation in the study for deriving the nondimensional fracture parameters are obtained using a fictitious crack model. It is inferred that for a relative size of initial crack length, critical load and corresponding crack opening displacement maintain a linear relationship in their nondimensional forms. The value of critical mouth opening displacement can also be determined for known value of peak load using the derived nondimensional equation, thus avoiding the measurement of the crack mouth opening displacement in the experiment. Further, the derived polynomial equations predict the double‐K fracture parameters of concrete with negligible error as compared to those obtained based on experimental results.

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“…Qing and Li [35] presented a traditional extreme peak load method for computing the fracture parameters of double-K method in which numerical integration is needed in the calculation. Using peak load method, Kumar et al [36] attempted to determine the fracture parameters of double-K fracture model based on peak load method for determining the two parameter fracture model [32]. Recently, Qing et al [35] proposed a simplified extreme peak load method for determining these fracture parameters.…”

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confidence: 99%

“…Recently, Qing et al [35] proposed a simplified extreme peak load method for determining these fracture parameters. The peak load method [36] requires at least three specimens with different sizes, or the same size but different initial notch lengths in tests whereas the traditional extreme peak load method [35] and the simplified extreme peak load method (SEPLM) [37] require only a single specimen to be tested for determining the fracture parameters. Further, the traditional extreme peak load method Qing et al [35] requires complicated integration procedure to calculate the critical effective crack length whereas the integration procedure is avoided in the simplified extreme peak load method [37].…”

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confidence: 99%

Numerical evaluation of simplified extreme peak load method for determining the double – K fracture parameters of concrete

Choubey¹,

Kumar²,

M³

2017

IJET

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Abstract-A simplified extreme peak load method for determining the double -K fracture parameters of concrete has been put forth in the recent research. The method was validated based on experimental test results available in the literature wherein, a significant deviation in predicted values of double -K fracture parameters for some specimens can be observed. The researchers attributed this deviation to measuring error in critical crack mouth opening displacement during fracture test which needs further investigation. Hence a systematic numerical investigation on predicted double -K fracture parameters of concrete using simplified extreme peak load method is presented in this study wherein the peak load and critical crack mouth opening displacement are obtained using fictitious crack model for varying specimen size and initial notch-length to depth ratio. For computation, use of numerical data seems to be precise as experimental data involves error in measuring of critical crack mouth opening displacement during fracture test. Present study reveals that the simplified extreme peak load method is applicable to a limited specimen size range between 200 to 300 mm. This method yields error in the predicted values of double-K fracture parameters of concrete for specimen size below 200mm and beyond 300mm.Keyword-Three-point bending geometry, Mode-I fracture, Concrete, Double-K fracture parameters, Simplified extreme peak load method, Weight function method. I. INTRODUCTIONThe crack propagation study and fracture parameters of concrete structures are described using nonlinear concrete fracture models such as cohesive crack model (CCM) or fictitious crack model (FCM) [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In last two decades, the double-K fracture model has attracted attention of researchers and academia around the world due to many advantages. This model uses LEFM principle in its modified form; it can describe the three important stages of crack propagation in concrete viz.: crack initiation, stable crack propagation and unstable fracture in concrete and the fracture parameters can be determined without use of close loop testing machine. This method is characterized by two material parameters: initial cracking toughness K IC ini and unstable fracture toughness K IC un . The initial cracking toughness is defined as the inherent toughness of the materials, which holds for loading at crack initiation when material behaves elastically and micro cracking is concentrated to a smallscale in the absence of main crack growth. The total toughness at the critical condition is termed as unstable toughness which is regarded as one of the material fracture parameters at the onset of the unstable crack propagation. The initial cracking toughness can be considered as a failure criterion in the design process for design of large size concrete structures like dam, nuclear reactor vessels, and liquid retaining structures wherein crack initiation is taken as one of design criteria. The unstable fracture toughness of the materia...

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Determination of double- K fracture parameters of concrete using peak load method

Cited by 30 publications

References 33 publications

Toughness enhancement and equivalent initial fracture toughness of cementitious composite reinforced with aligned steel fibres

Toughness enhancement and equivalent initial fracture toughness of cementitious composite reinforced with aligned steel fibres

Simplified equations for determining double‐K fracture parameters of concrete for 3‐point bending test

Numerical evaluation of simplified extreme peak load method for determining the double – K fracture parameters of concrete

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