Modelling time-dependent cracking in reinforced concrete using bond-slip Interface elements

Chong, Kak Tien; Gilbert, Raymond Ian; Foster, Stephen J.

doi:10.12989/cac.2004.1.2.151

Cited by 8 publications

(7 citation statements)

References 6 publications

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“…In this approach, developed in Bažant and Bažant and Oh, the fracture process zone is considered as a “blunt smeared crack‐band” and is “justified by the random nature of the microstructure.” These papers conclude the optimal crack‐band width should be of the order of three to five times the size of the largest aggregate particles ( d g ), with 3 d g being “the minimum acceptable for a homogeneous continuum modeling.” Where mesh sizes smaller than the optimal crack‐band dimension are used, a nonlocal procedure is needed . Here a nonlocal averaging procedure is adopted, such as separation of the local elastic strain and nonlocal cracking (or plastic) strain over a defined region of influence . Such a procedure was shown to work well by Foster et al for modeling ultra‐high performance prestressed concrete girders failing in shear.…”

Section: Finite Element Modeling Of a Large Beammentioning

confidence: 99%

“…The mean concrete cylinder compressive strength was taken as

f_{cm} = sans-serif37.2 sans-serifMPa

, as measured for the test. The tensile strength was taken as

f_{ct} = sans-serif0.33 \sqrt{{sans-serif-italicf}_{sans-serifcm}} = sans-serif2.01 sans-serifMPa

, allowing for residual tensions due to restrained shrinkage, the fracture energy was assumed to be

G_{f} = sans-serif60 sans-serifN / sans-serifm

and the concrete elastic modulus was taken as

E_{cm} = sans-serif28.9 sans-serifGPa

, as per the recommendations of AS 3600–2018 . The steel reinforcement was modeled with truss elements of area

A_{s} = sans-serif2100 {mm}^{2}

and a yield strength of

f_{y} = sans-serif550 sans-serifMPa

.…”

Section: Finite Element Modeling Of a Large Beammentioning

confidence: 99%

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On shear in members without stirrups and the application of energy‐based methods in light of 30 years of test observations

Bentz

Foster

2019

Structural Concrete

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In a recent paper in Structural Concrete, the authors Dönmez and Bažant explain that the theoretical background of the Model Code 2010 equations for one way and punching shear are not sufficiently grounded in theory and should instead use an energybased size effect law in their formulation to match behavior. To support this claim, finite element simulations were presented. In this paper the basic assumption that an energy-based method must govern the shear failure of beams without stirrups is questioned. These questions are shown to be based on the hardening behavior of aggregate interlock tests and the inability for slip strains to localize during shear failure. In addition to these theoretical arguments finite element analyses were conducted with a constitutive model that is energy-based but that also does an appropriate job at modeling aggregate interlock, an aspect that appears to be lacking in the analyses of Dönmez and Bažant. These new results are shown to better model the test results and confirm that aggregate interlock is important in explaining shear strength and therefore the size effect in shear for slender members. As such any concerns about the safety of the Model Code shear equations appear unwarranted. K E Y W O R D Sdesign codes, energy criteria, finite element simulations, fracture mechanics, model codes, shear

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Section: Finite Element Modeling Of a Large Beammentioning

confidence: 99%

“…The mean concrete cylinder compressive strength was taken as

f_{cm} = sans-serif37.2 sans-serifMPa

, as measured for the test. The tensile strength was taken as

f_{ct} = sans-serif0.33 \sqrt{{sans-serif-italicf}_{sans-serifcm}} = sans-serif2.01 sans-serifMPa

, allowing for residual tensions due to restrained shrinkage, the fracture energy was assumed to be

G_{f} = sans-serif60 sans-serifN / sans-serifm

and the concrete elastic modulus was taken as

E_{cm} = sans-serif28.9 sans-serifGPa

, as per the recommendations of AS 3600–2018 . The steel reinforcement was modeled with truss elements of area

A_{s} = sans-serif2100 {mm}^{2}

and a yield strength of

f_{y} = sans-serif550 sans-serifMPa

.…”

Section: Finite Element Modeling Of a Large Beammentioning

confidence: 99%

On shear in members without stirrups and the application of energy‐based methods in light of 30 years of test observations

Bentz

Foster

2019

Structural Concrete

Self Cite

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“…At this stage it is not possible to quantify separately the effects of creep‐ and shrinkage‐induced cracking on the increase in deflection with time. However, existing numerical models [11–14], taking into account the interaction between non‐mechanical deformations (creep, shrinkage, heat and water transport, etc.) and mechanical deformations in concrete, may be used to provide a more detailed interpretation of those experimental results and this will be the subject of a subsequent paper.…”

Section: Long‐term Experimentsmentioning

confidence: 99%

“…only six months. For more general conclusions, a longer period of time should be considered and be supported by numerical studies as well [11–14]. Indeed, over recent years, the measurement of long‐term creep, both in the laboratory and in existing structures, has indicated that creep continues to increase with time after many years under sustained stress [15–17].…”

Section: Influence Of Long‐term Effects On Crack Spacing In Relatiomentioning

confidence: 99%

Nachrichten des Verbandes Biologie, Biowissenschaften & Biomedizin in Deutschland

2014

Biologie in unserer Zeit

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“…First, verification of the proposed model is carried out against the thin slab and beam experiments reported by Chong et al (2004). A singly reinforced concrete slab was subjected to a sustained bending moment and moisture loss.…”

Section: Experimental Verification 31 Profile Of Intrinsic Shrinkagementioning

confidence: 99%

Time-Dependent Space-Averaged Constitutive Modeling of Cracked Reinforced Concrete Subjected to Shrinkage and Sustained Loads

Maekawa

Soltani

Ishida

et al. 2006

ACT

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Transient nonlinear analysis is proposed as a way of predicting the long-term deformation of cracked reinforced concrete and a mechanistic creep constitutive model for post-cracking tension-stiffness is presented. The effect of drying shrinkage is integrated into the predictive scheme using the thermo-hydro physics of porous media, and a simple equivalent method of analysis is discussed for the practical performance assessment of structural concrete. Careful verification of the model is carried out with respect to the creep deflection of RC beams and slabs subjected to multi-axial flexure. Three-dimensional fiber and plate & shell elements are used for the space discretization of the analysis domain. 1.IntroductionAmong the many industrial materials in common use, concrete is known as one that exhibits particularly large creep deformation even under daily working stresses. As a consequence, great efforts have been expended on elucidating the time-dependent characteristics of cementitious composites (e.g. ACI committee 209, 2005). The creep behavior of structural concrete has also been investigated, mainly in related to the design and management of pre-stressed concrete (PC). The accumulated knowledge addresses transient cable tension and its practical control particularly. In the case of slender reinforced concrete (RC) columns and thin space-shells, creep deflection results in an additional bending moment that may cause delayed buckling under axial compression. These problems generally relate to the pre-crack states, and crack-induced nonlinearities are not associated with such structural creep problems.In contrast, some need for the understanding of post-cracking creep in structural concrete has been recognized in connection with both enhanced serviceability limit state of new structures and the maintenance of existing structures with inherent defects. Current design codes generally specify a conservative value of concrete stress limit under the service load so as to avoid large inelastic creep. This kind of provision can occasionally lead to excessive thickness in the design of underground RC structures. More rational designs will depend on our ability to specify methods for long-term behavioral prediction. Excessive time-dependent deflections have also been noted in slender members when concrete with large shrinkage is used. These experiences indicate some need for improved serviceability prediction methods after cracking. Sato et al. (1983Sato et al. ( , 1987Sato et al. ( , 1995 and Gilbert et al. (2002Gilbert et al. ( , 2004 investigated the long-term deflection of RC beams/slabs and proposed computational models in consideration of drying shrinkage. Bond creep and cracked-concrete mechanics under sustained loads have also been intensely investigated with respect to concrete volume changes. Building on these original investigations, the authors aim in this paper to further enhance the modeling of post-cracking creep, which can also be linked with moisture migration analysis. Space-averaged tension-...

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Modelling time-dependent cracking in reinforced concrete using bond-slip Interface elements

Cited by 8 publications

References 6 publications

On shear in members without stirrups and the application of energy‐based methods in light of 30 years of test observations

On shear in members without stirrups and the application of energy‐based methods in light of 30 years of test observations

Nachrichten des Verbandes Biologie, Biowissenschaften & Biomedizin in Deutschland

Time-Dependent Space-Averaged Constitutive Modeling of Cracked Reinforced Concrete Subjected to Shrinkage and Sustained Loads

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