Numerical Study on Crack Dilatancy Part 2: Applications

Feenstra, P.H.; Borst, René de; Rots, J.G.

doi:10.1061/(asce)0733-9399(1991)117:4(754)

Cited by 18 publications

(5 citation statements)

References 3 publications

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“…9, September, 1994. ©ASCE, ISSN 0733-9399/94/0009-1945 light on the interface slip has been shed by studies of slip at interfaces of other types, including relative slip of rough crack surfaces [e.g., BaZant and Gambarova (1980), Divakar et al (1987), and Feenstra et al (1991)].…”

Section: Introductionmentioning

confidence: 99%

Size Effect in Fiber or Bar Pullout with Interface Softening Slip

Bažant¹,

Desmorat²

1994

J. Eng. Mech.

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The paper analyzes the size effect, which is an inevitable consequence of softening in the relation of interface shear stress and slip displacement bctwcen a fiber or reinforcing bar and the surrounding matrix. The problem is simplified as one-dimensional. Closed-form solutions of pull-pull and push-pull failures are obtained for a linear softening stress-slip law with residual strength, and for an exponential law without residual strength. The postpeak softening is shown to lead to localization of slip and interface shear fracture with a process zone of finite length. This zone propagates along the interface during the loading process, causing the distribution of interface shear stress to become strongly nonuniform. The larger the bar or fiber size, the stronger the nonuniformity. The size effect in geometrically similar pullout tests of different sizes is found to represent a smooth transition between two simple asymptotic cases: (1) The case of no size effcct, which occurs for very small sizes and is characteristic of plastic failure; and (2) the case of a size effect of the same type as in linear clastic fracture mechanics, in which the difference of the pullout stress from its residual value is proportional to the inverse square root of the fiber or bar diameter. An analytical expression for the transitional size effect is obtained. This expression is found to approximately agree with the generalized form of the size effect law proposed by BaZan!. The shape of the size effect curve is shown to be related to the shape of the softening stress-slip law for the interface. Finally, it is shown how measurements of the size effect can he used for identifying the interface properties, and a numerical example is given.

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Section: Introductionmentioning

confidence: 99%

Size Effect in Fiber or Bar Pullout with Interface Softening Slip

Bažant¹,

Desmorat²

1994

J. Eng. Mech.

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“…No separate stability study has been undertaken for the present model, in the sense of that undertaken by Feenstra et al [9,10], but as with any model that involves the simulation of softening behaviour, the tangent constitutive matrix of the present model can become non-positive definite. In such cases it can be advantageous, when the model is applied in a finite element code, to use an approximate tangent matrix, which maintains positive definiteness.…”

Section: Comments Thermodynamic Validity and Stabilitymentioning

confidence: 94%

Constitutive modelling of aggregate interlock in concrete

Jefferson

2002

Num Anal Meth Geomechanics

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SUMMARYA model for formed cracks in concrete is presented. The model can be used in isolation for existing cracks or linked with other damage or plasticity models and applied once a crack has fully formed. It can be applied directly to interface finite elements or used to control the behaviour of crack planes in more general constitutive models that are applied to 2D and 3D continuum elements. The focus of the present development is on aggregate interlock and crack closing behaviour, which is examined from available experimental data. A contact function is derived and is used to differentiate between three contact states. These states are named open, where there is no contact, interlock, for which the stresses depend upon the nearest distance to the contact surface and closed, for which the stresses depend upon the relative displacements directly. The model is developed within an elasto-plastic framework using effective stresses, which are related to the total stresses via a contact proportion function. The relationship between the effective normal and shear yield stresses is found to be parabolic and the yield shear stress to be dependent upon the opening and embedment displacements. The performance of the model is assessed against experimental data from shear-normal tests and it is concluded that the model is able to represent the key characteristics of the behaviour of formed cracks in concrete.

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“…Plane stress elements were adopted with a multi-directional fixed crack model for concrete based on strain decomposition and combining plasticity for compression and smeared cracking for tension. The FE meshes used in this work were uniform and generally followed orthogonal directions with standard mesh densities of around 10 divisions for the depth of the beam, which is similar to models developed by others [42,43,44]. Full details of the meshes, boundary conditions, material models and numerical solvers used are given elsewhere [10,11,19].…”

Section: Non-linear Finite Element Analysismentioning

confidence: 99%

The influence of aggregate fracture on the shear strength of reinforced concrete beams: an experimental and analytical research project

Sagaseta

2013

Structural Concrete

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High-performance concretes such as high-strength concrete (HSC) Keywords: shear strength, aggregate interlock, high-performance concrete, strut-and-tie method, non-linear finite element analysis IntroductionDesign methods for shear in reinforced concrete structures generally rely on shear transfer across cracks, which depends on the crack displacements and crack roughness. Aggregate fracture in high-strength concrete (HSC) and lightweight aggregate concrete (LWAC) leads to relatively smooth cracks as shown in Fig. 1, which is a major concern for structural engineers and researchers due to the reduction in aggregate interlock action and the potential reduction in shear strength. [5] observed a distinct reduction in strength due to aggregate fracture in their beams made with limestone aggregate. Gravel and limestone aggregates are commonly used in construction in the UK, for normal and high-performance concretes. This paper reviews the findings of the experimental and analytical research into the influence of aggregate fracture on the shear strength of beams with and without stirrups for different shear span/effective depth ratios. Influence of aggregate typeThe work carried out in this research confirmed that the lower bound of the compressive strength at which aggregates fracture at cracks is lower in concretes with limestone aggregate than in concretes with normal siliceous gravel (Fig. 1). This is due to the strong bond between the

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Numerical Study on Crack Dilatancy Part 2: Applications

Cited by 18 publications

References 3 publications

Size Effect in Fiber or Bar Pullout with Interface Softening Slip

Size Effect in Fiber or Bar Pullout with Interface Softening Slip

Constitutive modelling of aggregate interlock in concrete

The influence of aggregate fracture on the shear strength of reinforced concrete beams: an experimental and analytical research project

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