Boundary effect on concrete fracture and non-constant fracture energy distribution

Duan, Kai; Hu, Xiaozhi; Wittmann, Folker H.

doi:10.1016/s0013-7944(02)00223-0

Cited by 174 publications

(92 citation statements)

References 19 publications

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“…The first one is the case of a crack propagating towards a boundary. The fracture process zone (FPZ) is constrained by the boundary of specimen [8] and the energy required to propagate the crack should change. The specimen boundary will limit the development of the FPZ, and therefore, leads to a reduced fracture energy and strength [8,7,9,10].…”

Section: D Plate In Tensionmentioning

confidence: 99%

Boundary effect on weight function in nonlocal damage model

Krayani

Pijaudier‐Cabot

Dufour

2009

Engineering Fracture Mechanics

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Some insights on boundary effects in nonlocal damage modelling are addressed. Interaction stresses that are at the origin of nonlocality are expected to vanish at the boundary of a solid, in the normal direction to this boundary. Existing models do not account for such an effect. We introduce tentative modifications of the classical nonlocal damage model aimed at accounting for this boundary layer effect in a continuum modelling setting. Computations show that some nonnegligible differences may be observed between the classical and modified formulations. In a one dimensional spalling test, only the modified formulation provides a spall of finite nonzero thickness, whereas spalls smaller than the internal length cannot be obtained according to the original formulation. For the same set of model parameters, including the internal length, the fracture energy derived from the size effect test method is also very different according to both approaches. Parameters in the size effect laws for notched and unnotched specimens, obtained from computation of geometrically similar bending beams, are more consistent with the modified nonlocal model compared to the original nonlocal formulation.

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Section: D Plate In Tensionmentioning

confidence: 99%

Boundary effect on weight function in nonlocal damage model

Krayani

Pijaudier‐Cabot

Dufour

2009

Engineering Fracture Mechanics

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“…These F mechanisms cause the so-called tension softening of the material and can be particularly regarded as interpretation of the crack bending around aggregates, friction of cracks face and aggregate interlock, blinding of crack tip in pores, crack branching and others [1,3]. There were many attempts to capture/deal with the phenomena of the size/shape/boundary effect on fracture properties of quasi-brittle materials proposed with success in the last more than twenty years [5][6][7][8][9][10][11][12][13][14]; however, the applicability/validity of the suggested remedies are usually rather limited and not general. This is true also for the standardized work-of-fracture method for determination of fracture energy of concrete [15].…”

Section: Introductionmentioning

confidence: 99%

“…This is true also for the standardized work-of-fracture method for determination of fracture energy of concrete [15]. The value of fracture energy determined by this method is strongly dependent on the specimen size and geometry [9,10,12] This phenomenon is caused by the change in the size and shape of the FPZ during crack propagation, from which the change of energy dissipated in this area results. This change is determined by the distance and the position of the crack tip and the FPZ in relation to free surfaces of the specimen [12].…”

Section: Introductionmentioning

confidence: 99%

Modelling of size and shape of damage zone in quasi-brittle notched specimens – analytical approach based on fracture-mechanical evaluation of loading curves

Klon¹,

Veselý²

2016

Frattura Ed Integrità Strutturale

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ABSTRACT. An analysis focused on capturing the phenomenon of quasibrittle fracture is presented. Selected parameters relevant for quasi-brittle fracture are evaluated and an assessment of their dependence on the size and shape of the test specimen is studied. Determination of these fracture characteristics is based on the records of the fracture tests on notched specimens, particularly from recorded loading diagrams. A method of separation of the energy amounts released for the propagation of the (effective) crack and that dissipated within the volume of a large nonlinear zone at the crack tip -the fracture process zone -is introduced and tested on selected data from experimental campaigns published in the literature. The work is accompanied with own conducted numerical simulations using commercial finite element code with implemented cohesive crack model. Results from three-point bending tests on specimens of different sizes and relative notch lengths are taken into account in this study. The proposed model has only two parameters whose values are constant for all specimen sizes and notch lengths.

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“…A bilinear distribution of the local fracture energy along the crack path is therefore proposed. Duan et al [15,12,10] proposed also a bilinear fracture energy distribution where G f is function of the specimen width ( Fig. 1)…”

Section: Introductionmentioning

confidence: 99%

“…Therefore the energy dissipated due to fracture per unit length (or unit width) described by the stressstrain curves is constant. As the softening behaviour is nonlinear, the Levenberg-Marquardt [12,13] algorithm is used to perform inverse analysis. Only a part of the Load-CMOD curves is fitted in order to estimate the size-independent fracture energy.…”

Section: Introductionmentioning

confidence: 99%

Size-independent fracture energy of concrete at very early ages by inverse analysis

Matallah

Farah

Grondin

et al. 2013

Engineering Fracture Mechanics

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This paper deals with the analysis of fracture characteristics of concrete at very early ages. Experimentally, three-point bending tests are performed on concrete notched beams at very early age (before 24 h) to obtain the Load-Crack Mouth Opening Displacement (CMOD) curves. In order to find a trend of the fracture energy evolution, inverse analysis procedure is performed using finite element analysis. A damage softening model is used to describe the softening behaviour and a nonlinear inverse analysis algorithm (Levenberg-Marquardt) is adopted. As the softening damage model used does not take into account boundary effects, only a part of the Load-CMOD curves is fitted. Therefore, a good estimation of the size-independent fracture energy is obtained. The results obtained from the experimental test and the inverse analysis indicate an upward trend of the evolution of the fracture energy and other fracture concrete characteristics.

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Boundary effect on concrete fracture and non-constant fracture energy distribution

Cited by 174 publications

References 19 publications

Boundary effect on weight function in nonlocal damage model

Boundary effect on weight function in nonlocal damage model

Modelling of size and shape of damage zone in quasi-brittle notched specimens – analytical approach based on fracture-mechanical evaluation of loading curves

Size-independent fracture energy of concrete at very early ages by inverse analysis

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