Fictitious Rough Crack Model (FRCM): A Smeared Crack Modelling Approach to Account for Aggregate Interlock and Mixed Mode Fracture of Plain Concrete

Ungermann, Jan; Adam, Viviane; Claßen, Martin

doi:10.3390/ma13122774

Cited by 19 publications

(10 citation statements)

References 32 publications

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“…In the last few decades, several different shear test setups have been proposed with the purpose of providing a pure state of shear stress along a ligament. Examples of existing testing methods are push-off tests by [38,39] as well as notched tensile tests by [40,41], a comprehensive overview is given in [42]. Even though proposed for mode II crack characterization, none of these setups produces a pure shear situation [43].…”

Section: Shear Testmentioning

confidence: 99%

Mechanical Properties of Hardened 3D Printed Concretes and Mortars—Development of a Consistent Experimental Characterization Strategy

Meurer

Claßen

2021

Materials

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Today, it is already foreseeable that additive manufacturing of mortar and concrete has groundbreaking potential and will revolutionize or at least fundamentally change the way we build. In recent years, 3D concrete printing (3DCP) with extrusion-based deposition methods has been pushed forward by a growing research community. Albeit being regarded one of the most promising innovations in construction industry, a consistent characterization methodology for assessing the constitutive behavior of 3D printed, hardened cementitious materials is missing, so far, which hinders its widespread use in engineering practice. The major objective of this paper is to fill this gap by developing a new experimental framework that can thoroughly describe the mechanical properties of 3D printed cementitious materials. Based on both a review of state-of-the-art test setups and a comprehensive experimental campaign, the present paper proposes a set of easy-to-use experimental methods that allow us to assess flexural, tensile, shear and compressive strength as well as fracture energy of 3D printed concretes and mortars in a reliable and reproducible manner. The experimental results revealed anisotropic material behavior for flexural, tensile, shear and compressive loading. Furthermore, they confirm that interval time (time gap between deposition of subsequent layers) has a crucial effect on investigated material properties leading to a severe reduction in strength and fracture energy for longer interval times.

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Section: Shear Testmentioning

confidence: 99%

Mechanical Properties of Hardened 3D Printed Concretes and Mortars—Development of a Consistent Experimental Characterization Strategy

Meurer

Claßen

2021

Materials

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“…Fracture toughness under shear of some of the above-mentioned structural elements are presented, among others, in papers [ 100 , 101 , 102 , 103 , 104 , 105 , 106 ]. The wide range of examples of constructions, in which mode II fracture may determine the destruction, show the undoubted importance of the analyzed scientific problem.…”

Section: The Importance Of Researchmentioning

confidence: 99%

Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages

Golewski

2020

Materials

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This study investigated the influence of the curing time on the fracture toughness of concrete produced with different content of low calcium fly ash (LCFA). During the study, the amounts of 20% and 30% of pozzolanic additive were used. In order to observe the effect of the applied pozzolanic additive on the analyzed concrete properties, the obtained results were compared with the values obtained for the reference concrete. Compressive strength—fcm and fracture toughness, by using mode II loading—KIIc (shearing), were determined between the 3rd and 365th days of curing. In the course of experiments, changes in the development of cracks in individual series of concrete were also analyzed. In addition, the microstructures of all composites and the nature of macroscopic crack propagation in mature concretes were assessed. It was observed that the greatest increase in fracture toughness at shear was in the case of reference concrete during the first 28 days, whereas, in the case of concretes containing LCFA, in the period of time above 4 weeks. Furthermore, concrete without the LCFA additives were characterized by a brittle fracture. In contrast to it, concretes with LCFA additives are mainly characterized by a quasi-plastic process of failure. Moreover, most of the samples showed a typical pattern of the destruction that occurs as a result of shearing. The presented test results may be helpful in selecting the composition of concrete mixtures containing LCFA to be used in concrete and reinforced concrete structures subjected to shear loads.

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“…During the failure process, the kinematics of the crack faces are assumed to be in tension mode (mode I) without shear interaction. 25 The time of crack initiation t R (see also Figure 5 in the center) is determined to:…”

Section: Analytical Modelmentioning

confidence: 99%

“…This crack propagation velocity is assumed to be constant, so that this analytical model is not dependent on any further description of the damage mechanisms (eg, crack‐tip mechanics, fracture toughness). During the failure process, the kinematics of the crack faces are assumed to be in tension mode (mode I) without shear interaction 25 . The time of crack initiation t R (see also Figure 5 in the center) is determined to:

t_{R} = \frac{f_{t}}{\overset{ε}{true} \cdot E}

…”

Section: Analytical Modelmentioning

confidence: 99%

The crack propagation velocity as a reason for the strain rate effect of concrete: An analytical model

Mosig

Curbach

2020

Civil Engineering Design

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An analytical model is presented in this paper which, based on the maximum crack velocity, provides a hypothesis for one of the reasons of the increase in tensile strength of concrete under high loading rates. Due to the fact that the formation of cracks needs a certain time to pass through the cross section and not happens suddenly, stresses can still be transmitted over the remaining uncracked cross section during this time. The hypothesis is that at high loading rates, the increase in externally induced stresses can be greater than the decrease in the load-bearing cross-sectional area due to limited crack propagation velocity, which results in an externally measurable increase in strength. This measured strength increase depends on the stress distribution in the crack plane. In this paper two variants of this stress distribution during the failure process are described, and their effect on the increase in strength is mathematically evaluated.

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Fictitious Rough Crack Model (FRCM): A Smeared Crack Modelling Approach to Account for Aggregate Interlock and Mixed Mode Fracture of Plain Concrete

Cited by 19 publications

References 32 publications

Mechanical Properties of Hardened 3D Printed Concretes and Mortars—Development of a Consistent Experimental Characterization Strategy

Mechanical Properties of Hardened 3D Printed Concretes and Mortars—Development of a Consistent Experimental Characterization Strategy

Changes in the Fracture Toughness under Mode II Loading of Low Calcium Fly Ash (LCFA) Concrete Depending on Ages

The crack propagation velocity as a reason for the strain rate effect of concrete: An analytical model

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