Composite behavior of concrete materials under high temperatures

Xotta, Giovanna; Mazzucco, Gianluca; Salomoni, Valentina; Majorana, C. E.; Willam, Kaspar

doi:10.1016/j.ijsolstr.2015.03.016

Cited by 66 publications

(25 citation statements)

References 26 publications

(36 reference statements)

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“…For example, the obtained results can be used to properly design FRP stiffeners applied to concrete structures that are prone to various damaging phenomena (see, e.g., [38]). It should be noted that the case of a thermal variation Δ (thermal variations can sensibly affect the mechanical behaviour of structural elements, as shown in [39,40]) acting on the beam (for the effect produced by thermal loads on concrete structures, see, e.g., [38]) can be studied as the loading case of two symmetric axial end forces by assuming…”

Section: Resultsmentioning

confidence: 99%

Euler-Bernoulli Nanobeam Welded to a Compressible Semi-Infinite Substrate

Maida¹,

Falope²

2016

Modelling and Simulation in Engineering

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The contact problem of an Euler-Bernoulli nanobeam of finite length bonded to a homogeneous elastic half plane is studied in the present work. Both the beam and the half plane are assumed to display a linear elastic behaviour under infinitesimal strains. The analysis is performed under plane strain condition. Owing to the bending stiffness of the beam, shear and peeling stresses arise at the interface between the beam and the substrate within the contact region. The investigation allows evaluating the role played by the Poisson ratio of the half plane (and, in turn, its compressibility) on the beam-substrate mechanical interaction. Different symmetric and skew-symmetric loading conditions for the beam are considered, with particular emphasis to concentrated transversal and horizontal forces and couples acting at its edges. It is found that the Poisson ratio of the half plane affects the behaviour of the interfacial stress field, particularly at the beam edges, where the shear and peel stresses are singular.

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Section: Resultsmentioning

confidence: 99%

Euler-Bernoulli Nanobeam Welded to a Compressible Semi-Infinite Substrate

Maida¹,

Falope²

2016

Modelling and Simulation in Engineering

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“…In the mesoscale model, concrete is assumed as a composite material with two periodically distributed mesoscale components, cement paste and aggregates, represented by multiphase hygroscopic and heat conducting rigid porous media partially saturated with liquid water, e.g. [4,8]. The detailed description of the assumptions adopted for developing the model is given in our previous work [17].…”

Section: The Mesoscale Modelmentioning

confidence: 99%

Homogenization of Transport Processes and Hydration Phenomena in Fresh Concrete

Beneš

Štefan

2020

Acta Polytech

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The problem of hydration and transport processes in fresh concrete is strongly coupled and non- inear, and therefore, very diﬃcult for a numerical modelling. Physically accurate results can be obtained using ﬁne-scale simulations, which are, however, extremely time consuming. Therefore, there is an interest in developing new physically accurate and computationally eﬀective models. In this paper, a new fully coupled two-scale (meso-macro) homogenization framework for modelling of simultaneous heat transfer, moisture ﬂows, and hydration phenomena in fresh concrete is proposed. A modiﬁed mesoscalemodelisﬁrstintroduced. Inthismodel, concreteisassumedasacompositematerialwithtwo periodically distributed mesoscale components, cement paste and aggregates. A homogenized model is then derived by an upscaling method from the mesoscale model. The coeﬃcients for the homogenized model are obtained from the solution of a periodic cell problem. For solving the periodic cell problem, two approaches are used – a standard ﬁnite element method and a simpliﬁed closed-form approximation taken from literature. The homogenization framework is then implemented in MATLAB environment and ﬁnally employed for illustrative numerical experiments, which verify that the homogenized model provides physically accurate results comparable with the results obtained by the mesoscale model. Moreover, it is veriﬁed that, using the homogenization framework with a closed-form approach to the periodic cell problem, signiﬁcant computational cost savings can be achieved.

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“…However concrete is not just a two-phase composite; it has been found that the presence of grains in the cement paste causes a thin layer of matrix material surrounding each inclusion to be more porous than the bulk of the surrounding cement paste matrix. This layer is named interfacial transition zone (ITZ) and has relevant effects on the properties of concrete, being likely to act as the "weak link in the chain" when compared to the bulk cement paste and the aggregate particles [15,16].…”

Section: Concrete As a Multiphase Materialsmentioning

confidence: 99%

Fire Spalling Prevention via Polypropylene Fibres: A Meso- and Macroscale Approach

Mazzucco

Xotta

2016

Modelling and Simulation in Engineering

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A deep understanding of concrete at the mesoscale level is essential for a better comprehension of several concrete phenomena, such as creep, damage, and spalling. The latter one specifically corresponds to the separation of pieces of concrete from the surface of a structural element when it is exposed to high and rapidly rising temperatures; for this phenomenon a mesoscopic approach is fundamental since aggregates performance and their thermal properties play a crucial role. To reduce the risk of spalling of a concrete material under fire condition, the inclusion of a low dosage of polypropylene fibres in the mix design of concrete is largely recognized. PP fibres in fact evaporate above certain temperatures, thus increasing the porosity and reducing the internal pressure in the material by an increase of the voids connectivity in the cement paste. In this work, the contribution of polypropylene fibres on concrete behaviour, if subjected to elevated thermal ranges, has been numerically investigated thanks to a coupled hygrothermomechanical finite element formulation. Numerical analyses at the macro-and mesoscale levels have been performed.

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Composite behavior of concrete materials under high temperatures

Cited by 66 publications

References 26 publications

Euler-Bernoulli Nanobeam Welded to a Compressible Semi-Infinite Substrate

Euler-Bernoulli Nanobeam Welded to a Compressible Semi-Infinite Substrate

Homogenization of Transport Processes and Hydration Phenomena in Fresh Concrete

Fire Spalling Prevention via Polypropylene Fibres: A Meso- and Macroscale Approach

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