Determining initial fracture toughness of concrete for split-tension specimens based on the extreme theory

Qing, Longbang; Dong, Mowen; Guan, Junfeng

doi:10.1016/j.engfracmech.2017.11.011

Cited by 25 publications

(5 citation statements)

References 25 publications

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“…The mechanical properties of the primary materials are listed in Table 1. Among them, the tensile strength and elastic modulus of mortar were calculated according to empirical formulas shown in Equations (4)-(6), as described in [34,35]. The value of c/w was determined according to [26].…”

Section: Determination Of Property Parametersmentioning

confidence: 99%

Numerical Simulation on Size Effect of Fracture Toughness of Concrete Based on Mesomechanics

Wang

Guan

et al. 2020

Materials

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The fracture performance of concrete is size-dependent within a certain size range. A four-phase composite material numerical model of mesofracture considering a mortar matrix, coarse aggregates, an interfacial transition zone (ITZ) at the meso level and the initial defects of concrete was established. The initial defects were assumed to be distributed randomly in the ITZ of concrete. The numerical model of concrete mesofracture was established to simulate the fracture process of wedge splitting (WS) concrete specimens with widths of 200-2000 mm and three-point bending (3-p-b) concrete specimens with heights of 200-800 mm. The fracture process of concrete was simulated, and the peak load (P max ) of concrete was predicted using the numerical model. Based on the simulating results, the influence of specimen size of WS and 3-p-b tests on the fracture parameters was analyzed. It was demonstrated that when the specimen size was large enough, the fracture toughness (K IC ) value obtained by the linear elastic fracture mechanics formula was independent of the specimen size. Meanwhile, the improved boundary effect model (BEM) was employed to study the tensile strength (f t ) and fracture toughness of concrete using the mesofracture numerical model. A discrete value of β = 1.0-1.4 was a sufficient approximation to determine the f t and K IC values of concrete.Materials 2020, 13, 1370 2 of 16 considered that when the height of the specimen reaches 800 mm, the measured fracture toughness K IC value no longer has size effects [4]. The similar conclusion drawn by Bazant [5] is that the mechanical parameters measured for specimens in a certain size range had size effects. That is to say, when the size of the specimens was small enough or large enough, the mechanical properties and fracture parameters remained unchanged. In view of this experimental phenomenon, Weibull [8,9] considered that the size dependence was due to the increase in the probability of encountering low-strength material elements with increasing structure sizes. Based on the law of extreme strength distribution, a size effect statistical theory was proposed. However, this theory was limited to structures that fail at the beginning of macro-cracks and small structures that only cause negligible stress redistribution in the fracture process zone when they fail. Subsequently, based on the energy theory, Bazant et al. [5] proposed a size effect theory of fracture mechanics for geometrically similar specimens with a size range of approximately 1:20 notches. Based on the concept of fractals, Carpinteri et al.[6] established a multi-fractal size effect law that reflected the unstable cracking of structures when the size range was approximately 1:10. Hu [7] concluded that the initial crack and ligament depth should be far from the specimen boundary to reflect the true mechanical parameters of a material, independent of size. Based on this, the boundary effect theory was established. In addition to this basic theory, indirect size effects such as the boundary layer ...

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Section: Determination Of Property Parametersmentioning

confidence: 99%

Numerical Simulation on Size Effect of Fracture Toughness of Concrete Based on Mesomechanics

Wang

Guan

et al. 2020

Materials

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“…The model combines the fictitious crack concept reflecting the softening characteristics of concrete with the stress intensity factor at the tip of the notch. In recent years, domestic and international academics have conducted a large number of studies and researches in the specimen form [15,16], calculating methods [17][18][19][20], influencing factors [21][22][23] theoretical extensions and applications [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Fracture behaviour of concrete with different replacement rates of iron tailings sand based on double-K criterion

Zhang

Kang

et al. 2023

Frattura Ed Integrità Strutturale

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The article conducts a study on the iron tailings sand concrete's fracture behaviour based on the double-K criterion. Five sets of standard three-point bending beam specimens of concrete with 0%, 25%, 50%, 75% and 100% iron tailings sand replacement river sand respectively were fracture tested, and the P-CMOD and P- ε curves of each set of specimens were measured to determine the pertinent fracture parameters. The specimens were also microscopically tested using scanning electron microscopy and mercury intrusion porosimetry. The results demonstrate that the fracture processes and damage patterns of iron tailings sand concrete and river sand concrete are comparable; the addition of iron tailings sand improves initial cracking load and initial cracking toughness more significantly than unstable cracking load and unstable cracking toughness; the ductility of iron tailings sand concrete is marginally inferior; and the results of microscopic tests demonstrate that the addition of iron tailings sand can improve the morphology and pore structure of the interface transition zone. Therefore, from the assessment of fracture mechanics, iron tailings sand can totally replace river sand in equivalent quantities for concrete preparation, which will provide great potential for the secondary use of iron tailings sand.

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“…The fracture toughness 5–8 and strength 9–14 are the two criteria typically used for the analysis of crack stability or crack growth of concrete. For the fracture toughness criterion, various studies considered the initial fracture toughness

K_{IC}^{ini}

, as the material parameter of concrete, for crack propagation 15–23 . The initial fracture toughness

K_{IC}^{ini}

corresponds to the initial cracking load P ini .…”

Section: Introductionmentioning

confidence: 99%

“…For the fracture toughness criterion, various studies considered the initial fracture toughness K ini IC , as the material parameter of concrete, for crack propagation. [15][16][17][18][19][20][21][22][23] The initial fracture toughness K ini IC corresponds to the initial cracking load P ini . If concrete is considered homogeneous, then K ini IC can be directly calculated using P ini based on the linear elastic fracture mechanics (LEFM).…”

Section: Introductionmentioning

confidence: 99%

Initial cracking strength and initial fracture toughness from three‐point bending and wedge splitting concrete specimens

Yao

Guan

et al. 2020

Fatigue Fract Eng Mat Struct

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In this study, a concept of initial cracking strength of concrete was elaborated. A fracture model and associated methods for determining independent initial cracking strength and initial fracture toughness by the three‐point bending (3‐p‐b) and wedge splitting (WS) concrete specimens are presented. The initial cracking strength and initial fracture toughness can be simultaneously determined using a curve fitting method from the proposed fracture model. All of the initial fracture curves were obtained by the determined concrete materials. The initial loads of the 3‐p‐b and WS specimens were predicted on the basis of the curves with ±15% ranges. Furthermore, the initial cracking strength and the initial fracture toughness of concretes were directly determined by analytical functions. The determined values within ±15% ranges cover most of the initial loads of the 3‐p‐b and WS specimens.

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Determining initial fracture toughness of concrete for split-tension specimens based on the extreme theory

Cited by 25 publications

References 25 publications

Numerical Simulation on Size Effect of Fracture Toughness of Concrete Based on Mesomechanics

Numerical Simulation on Size Effect of Fracture Toughness of Concrete Based on Mesomechanics

Fracture behaviour of concrete with different replacement rates of iron tailings sand based on double-K criterion

Initial cracking strength and initial fracture toughness from three‐point bending and wedge splitting concrete specimens

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