scholarly journals Statistical Damage Constitutive Model for High-Strength Concrete Based on Dissipation Energy Density

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 800
Author(s):  
Liangliang Zhang ◽  
Hua Cheng ◽  
Xiaojian Wang ◽  
Jimin Liu ◽  
Longhui Guo
Keyword(s):  
Energy Density ◽  
High Strength Concrete ◽  
Elastic Strain ◽  
Elastic Strain Energy ◽  
Peak Stress ◽  
High Strength ◽  
Dissipation Energy ◽  
Strength Concrete ◽  
Elastic Strain Energy Density ◽  
Statistical Damage

To study the energy evolution law and damage constitutive behavior of high-strength concrete based on the conventional triaxial compression tests of C60 and C70 high-strength concrete subjected to five different confining pressures, the failure characteristics of high-strength concrete are analyzed at different confining pressures, and the evolution of the input energy density, elastic strain energy density, and dissipation energy density with axial strain and confining pressure are quantified. Combined with a continuous damage theory and non-equilibrium statistical method, the ratio of dissipation energy density of concrete to dissipation energy density corresponding to peak stress is used as the mechanical parameter. Assuming that the mechanical parameter obeys the Weibull distribution laws, the statistical damage variable describing the damage characteristics of concrete were derived. According to the Lemaitre strain equivalent principle, the damage variable is introduced to the generalized Hooke law to establish the statistical damage constitutive model for high-strength concrete. The results show that: (1) the input energy density and dissipation energy density increases with the increase of axial strain, while the elastic strain energy density increases first and then decreases as a function of the axial strain and reaches the maximum value at the peak stress; (2) the input, elastic strain, and dissipated energy densities corresponding to the peak stress of the two high-strength concretes all increase as a function of confining pressure, and the elastic strain energy density corresponding to the peak stress increases linearly as a function of the confining pressure; (3) the statistical damage constitutive model results of C60 and C70 high-strength concrete are in good agreement with the test results, and the average relative standard deviations are only 3.64% and 3.99%. These outcomes verify the rationality and accuracy of the model.

Comparison Analysis on the Mechanical Properties of HSC and NSC after the Action of High Temperatures

2014 ◽  
Vol 1014 ◽  
pp. 49-52
Author(s):  
Xiao Ping Su
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
High Strength Concrete ◽  
Elasticity Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
High Strength ◽  
Peak Strain ◽  
Strength Concrete

With the wide application of high strength concrete in the building construction,the risk making concrete subject to high temperatures during a fire is increasing. Comparison tests on the mechanical properties of high strength concrete (HSC) and normal strength concrete (NSC) after the action of high temperature were made in this article, which were compared from the following aspects: the peak stress, the peak strain, elasticity modulus, and stress-strain curve after high temperature. Results show that the laws of the mechanical properties of HSC and NSC changing with the temperature are the same. With the increase of heating temperature, the peak stress and elasticity modulus decreases, while the peak strain grows rapidly. HSC shows greater brittleness and worse fire-resistant performance than NSC, and destroys suddenly. The research and evaluation on the fire-resistant performance of HSC should be strengthened during the structural design and construction on the HSC buildings.

scholarly journals A Modified Bursting Energy Index for Evaluating Coal Burst Proneness and Its Application in Ordos Coalfield, China

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1729
Author(s):  
Xuewei Liu ◽  
Quansheng Liu ◽  
Bin Liu ◽  
Yongshui Kang
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Elastic Strain ◽  
Strain Energy ◽  
Coal Mines ◽  
Elastic Strain Energy ◽  
Peak Strength ◽  
Energy Index ◽  
Total Input ◽  
Elastic Strain Energy Density

Coal burst is a type of dynamic geological hazard in coal mine. In this study, a modified bursting energy index, which is defined as the ratio of elastic strain energy at the peak strength to the released strain energy density at the post-peak stage, was proposed to evaluate the coal burst proneness. The calculation method for this index was also introduced. Two coal mines (PJ and TJH coal mines) located in Ordos coalfield were used to verify the validity of the proposed method. The tests results indicate that modified bursting energy index increases linearly with increasing uniaxial compressive strength. The parameter A, which is used to fit relation between total input and elastic strain energy density, has a significant effect on the modified bursting energy index. A large value of parameter A means more elastic strain energy before the peak strength while a small value indicates most of input energy was dissipated. Finally, the coal burst proneness of these two coal mines was evaluated with the modified index. The results of modified index are consistent with that of laboratory tests, and more reasonable than that from original bursting energy index because it removed the dissipated strain energy from the total input strain energy density.

Performance Comparison between High Strength Concrete and Ordinary Concrete under Mixed Erosion and Freeze-Thaw Cycling

2010 ◽  
Vol 163-167 ◽  
pp. 1667-1672
Author(s):  
Jian Zhang ◽  
Bo Diao ◽  
Yan Dong Li ◽  
Xiao Ning Zheng
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
High Strength Concrete ◽  
Mass Loss Rate ◽  
Peak Stress ◽  
High Strength ◽  
Performance Comparison ◽  
Freeze Thaw ◽  
Strength Concrete ◽  
Ordinary Concrete

: Performance of high strength concrete and ordinary concrete under alternating action of mixed erosion and freeze-thaw cycling were compared. The erosion solution was mixed by weight of 3% sodium chloride and 5% sodium sulfate. Results showed that, after 200 freeze-thaw cycles, the effect of surface scaling of ordinary concrete was more significant than that of high strength concrete, and the mass loss rate of ordinary concrete was much higher; The relative dynamic modulus of elasticity of high strength concrete slightly increased by 2.99%, while that of ordinary concrete decreased more than 13%. Compressive strength and elastic modulus of high strength and ordinary concrete behaved almost in the same way in the first 50 freeze-thaw cycles, with the increase of freeze-thaw cycles in the following test, the compressive strength and elastic modulus of ordinary concrete showed larger reductions than these of high strength concrete. As the freeze-thaw cycles increased, the corresponding strain to the peak stress of high strength concrete decreased, but it increased for ordinary concrete.

On the definition of elastic strain energy density in fatigue modelling

2019 ◽  
Vol 121 ◽  
pp. 237-242 ◽  
Author(s):  
Ali A. Roostaei ◽  
Amirhossein Pahlevanpour ◽  
Seyed Behzad Behravesh ◽  
Hamid Jahed
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Definition Of ◽  
Elastic Strain Energy Density

scholarly journals Strain energy-and stress-based approaches revisited in notch fatigue of ductile steels

2018 ◽  
Vol 165 ◽  
pp. 14009 ◽  
Author(s):  
Bruno Atzori ◽  
Mauro Ricotta ◽  
Giovanni Meneghetti
Keyword(s):  
Energy Density ◽  
Plastic Strain ◽  
Strain Energy Density ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Fatigue Behaviour ◽  
Strength Reduction Factor ◽  
Plastic Strain Energy ◽  
Elastic Strain Energy Density

The constant amplitude, zero-mean stress, axial-fatigue behaviour of plain and bluntly notched AISI 304 L stainless steel specimens is investigated in terms of strain energy density. Concerning plain material, it was found that at the fatigue knee the plastic strain energy density is 1.49 times higher than the elastic strain energy density. In the authors’ opinion, the presence of plasticity at the fatigue knee is responsible for the unsuitableness of classical stress - based approaches to synthesise the fatigue behaviour of this material. On the contrary, the elastic-plastic strain energy density was found an efficient parameter to rationalise in a single scatter band fatigue data of plain and bluntly notched specimens. Based on this result, the classic stress-and the point stress-based approaches were revisited taking into account the presence of plasticity at the fatigue knee, by introducing an equivalent fully elastic material having a linear elastic strain energy density at the fatigue knee equal to that of the actual material. Accordingly, a coefficient of plasticity Kp was successfully introduced to modify the classical definition of fatigue strength reduction factor, Kf.

Spectral decomposition of the linear elastic tensor for monoclinic symmetry

1999 ◽  
Vol 55 (4) ◽  
pp. 635-647 ◽  
Author(s):  
Pericles S. Theocaris ◽  
Dimitrios P. Sokolis
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Stress And Strain ◽  
Monoclinic Symmetry ◽  
Compliance Tensor ◽  
Characteristic Values ◽  
Elastic Strain Energy Density

The compliance fourth-rank tensor related to crystalline or other anisotropic media belonging to the monoclinic crystal system is spectrally decomposed for the first time, and its characteristic values and idempotent fourth-rank tensors are established. Further, it is proven that the idempotent tensors resolve the stress and strain second-rank tensors into eigentensors, thus giving rise to a decomposition of the total elastic strain-energy density into non-interacting strain-energy parts. Several examples of representative inorganic crystals of the monoclinic system illustrate the results of the theoretical analysis. It is also proven that the essential parameters required for a coordinate-invariant characterization of the elastic properties of a crystal exhibiting monoclinic symmetry are both the six characteristic values of the compliance tensor and seven dimensionless parameters. These material constants, referred to as the eigenangles, are shown to be accountable for the orientation of the stress and strain eigentensors, when represented in a stress coordinate system. Finally, the restrictions dictated by the classical thermodynamical argument on the elements of the compliance tensor, which are necessary and sufficient for the elastic strain-energy density to be positive definite, are investigated for the monoclinic symmetry.

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