Thermo-mechanically-induced thermal conductivity change and its effect on the behaviour of concrete

Nguyen, T.N.; Pham, Duc Tho; Vu, Minh‐Ngoc

doi:10.1016/j.conbuildmat.2018.11.146

Cited by 18 publications

(7 citation statements)

References 34 publications

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“…Equivalent strain ε eq is determined: The softening curve of the stress-strain response is controlled by the fracture energy G fc (for the case of pure compression or G ft (for the case of pure tension): (10) with i = c (compression) or t (tension); ωi = G fi /f i ; e =||e|| is the equivalent crack opening parameter. e=h e ωε (11) In case of pure compression:…”

Section: Mechanical Lattice Modelmentioning

confidence: 99%

Experimental and Mesoscopic Lattice Numerical Investigation of Increase of Chloride Diffusivity Coefficient during Uniaxial Loading Model

Truong¹,

Tho²

2020

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This paper presents experimental and simulation results of the change in the chloride diffusion coefficient of concrete C40 (f’c=40 MPa) during axial loading. Test Method for Electrical Indication was used to measure the chloride diffusivity of the concrete sample during the axial loading. A mesoscopic lattice model is proposed to describe the variation of chloride diffusion coefficient versus damage variable. In such a model, the domain of material is discretized randomly by using Voronoi tessellation for the transport element and Delaunay triangulation for a mechanical element. At the mesoscale, the concrete is constituted by three phases: aggregate, cement paste and ITZ, in which aggregate is assumed to be elastic while cement matrix and ITZ are represented by a damage model with softening. The experimental and numerical results show that in the first stage, without crack (s < 40%smax), the chloride diffusion coefficient remains almost constant, however in the crack initiation and propagation stage (s = 60-80%smax) chloride diffusion coefficient increases significantly. An empirical power model is also proposed to describe the increase of the chloride diffusion coefficient versus stress level and damage variable.

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Section: Mechanical Lattice Modelmentioning

confidence: 99%

Experimental and Mesoscopic Lattice Numerical Investigation of Increase of Chloride Diffusivity Coefficient during Uniaxial Loading Model

Truong¹,

Tho²

2020

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“…More sophisticated prediction of the structural performance is related to calibration of the thermal degradation of concrete materials [ 8 , 10 ] and thermal stresses [ 11 , 12 ], as a result of the temporal and spatial evolution of temperature fields. Furthermore, the heat transfer process is also influenced by the mass transfer [ 13 , 14 ], as a result of vaporization and dehydration, and the cracking [ 15 , 16 ], as a result of mechanical response. In this aspect, hygro-thermo-chemo-mechanical models were also proposed [ 17 ], which is beyond the scope of this work.…”

Section: Introductionmentioning

confidence: 99%

Transient Nonlinear Heat Conduction in Concrete Structures: A Semi-Analytical Approach

Wang

Chen

Koenders

et al. 2023

Entropy

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Thermal loading, especially in fire scenarios, challenges the safety and long-term durability of concrete structures. The resulting heat propagation within the structure is governed by the heat conduction equation, which can be difficult to solve analytically because of the nonlinearity related to the thermophysical properties of concrete. A semi-analytical approach for the transient nonlinear heat conduction problem in concrete structures was established in the present work. The nonlinearity related to the temperature-dependent thermal conductivity, mass density, and specific heat capacity of heated concrete was taken into consideration. A Taylor series approximate solution was first established within a small neighborhood, employing the Boltzmann transformation in combination with the mean value theorem. Thereafter, it was extended to the whole domain by utilizing the Bernstein polynomial. The semi-analytical approach was validated by comparing it with the numerical results of two independent Finite Element simulations of nonlinear heat conduction along concrete plates, subjected to either moderate or fierce thermal loading. Absolute values of the relative errors are smaller than 5%. The validated semi-analytical approach was further applied to prediction of the temporal evolution of the temperature field of a scaled model of a subway station, subjected to fire disaster. The nonlinearities, related to the time-dependent surface temperature and the temperature-dependent thermophysical properties of concrete, were taken into consideration. The predictions agree well with the experimental measurements. The established semi-analytical approach exhibits good accuracy and stability, providing insight into the interaction between the thermophysical properties of concrete in the heat conduction process.

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“…Ferreira [17] developed a numerical model for the simulation of reinforced concrete columns in a fire situation, also based on the Finite Element Method, in order to predict the structural behavior under high temperatures. Nguyen et al [18] studied the thermal conductivity change of concrete when exposed to both mechanical and thermal loads through a numerical three-phase plane model using lattice discretization, where damage variable is accounted via crack opening. Rodovalho et al [19] analyzed the mechanical resistance of concrete blocks subjected to compression and in a fire situation.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of mechanical damage on concrete under high temperatures

Assis

Sasso

Farage

et al. 2022

Rev. IBRACON Estrut. Mater.

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Concrete is a widespread material all over the world. Due to this material’s heterogeneity and structural complexity, predicting the behavior of concrete structures under extreme environmental conditions is a very challenging task. High temperatures lead to microstructural changes which affect the macrostructural performance. In this context, computational tools that allow the simulation of structures may assist the analysis, by reproducing varied situations of thermal and mechanical loading and boundary conditions. In order to contribute to this scenario, this study proposes a numerical methodology to simulate the thermomechanical behavior of concrete under temperature gradients, through inverse analyses and a user subroutine implemented in Abaqus software. Thermal loading effects were considered as loading data for a damage model. Experimental data available in the literature was adopted for adjustment and validation purposes. The preliminary results presented herein encourage further improvements so as to allow realistic simulations of such an important aspect of concrete’s behavior.

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Thermo-mechanically-induced thermal conductivity change and its effect on the behaviour of concrete

Cited by 18 publications

References 34 publications

Experimental and Mesoscopic Lattice Numerical Investigation of Increase of Chloride Diffusivity Coefficient during Uniaxial Loading Model

Experimental and Mesoscopic Lattice Numerical Investigation of Increase of Chloride Diffusivity Coefficient during Uniaxial Loading Model

Transient Nonlinear Heat Conduction in Concrete Structures: A Semi-Analytical Approach

Numerical analysis of mechanical damage on concrete under high temperatures

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