scholarly journals Analysis of Biaxial Mechanical Properties and Failure Criterion of Self-Compacting Concrete

2021 ◽  
Vol 8 ◽  
Author(s):  
Jun Zhang ◽  
Chen Li ◽  
Congxiang Zhu ◽  
Zhiqing Zhao
Keyword(s):  
Mechanical Properties ◽  
Principal Stress ◽  
Compressive Stress ◽  
Failure Modes ◽  
Biaxial Loading ◽  
Biaxial Tension ◽  
Biaxial Compression ◽  
Self Compacting Concrete ◽  
Ordinary Concrete ◽  
Biaxial Mechanical Properties

Biaxial compression-compression, biaxial tension-compression and compression-shear tests were carried out on self-compacting concrete (SCC) using the rock true triaxial machine and compression-shear hydraulic servo machine to explore the biaxial mechanical properties of SCC. The failure modes and stress-strain curves of SCC under different loading conditions were obtained through experiment. Based on the comparison with the biaxial loading test data of ordinary concrete, the following conclusions are drawn: the failure modes and failure mechanisms under biaxial compression-compression and biaxial tension-compression are similar between SCC and ordinary concrete. Under compression-shear loading, the oblique cracks formed on the lateral surface of the specimen parallel to the shear direction gradually increased and the friction marks on the shear failure section were gradually deepened with the increase of axial compression ratio. The development trend of the stress-strain curve in the principal stress direction was not related to the lateral stress. Under the influence of lateral compressive stress, the principal compressive stress of SCC was increased by 55.78% on average; under biaxial tension-compression, the principal tensile stress of SCC had a maximum reduction of 62.79%; and under the compression-shear action, the shear stress of SCC had a maximum increase of 3.35 times. Compared with the biaxial stress test data of ordinary concrete, it can be seen that the lateral compressive stress had a more significant effect on the principal stress of SCC under biaxial loading. Subsequently, the strength criterion equations of SCC under biaxial loading were proposed based on the principal stress space and octahedral space stress respectively, which have shown good applicability in practice.

scholarly journals Experimental Analysis and Failure Criterion of Plain Concrete Subjected to Biaxial Loading under Fixed Lateral Loading

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Zhenpeng Yu ◽  
Xue Sun ◽  
Furong Li
Keyword(s):  
Principal Stress ◽  
Failure Criterion ◽  
Failure Modes ◽  
Biaxial Loading ◽  
Plain Concrete ◽  
Failure Criteria ◽  
Lateral Loading ◽  
Biaxial Compression ◽  
Proportional Loading ◽  
Stress Ratios

By using a rock true triaxial apparatus hydraulic servo machine, biaxial loading experiments including biaxial compression-compression and biaxial compression-tension with fixed lateral loading on plain concretes were conducted and the stress-strain curves of plain concrete under various stress ratios were obtained. After determining the peak principal stress, the damage modes of plain concrete under various stress ratios were analyzed and the law of strength in the principal stress direction was studied as well. The experimental findings show that, under the fixed lateral loading, the failure modes of plain concrete under biaxial compression-compression and biaxial compression-tension are very similar to those under the equal proportional loading, but with higher amplitude of variation. In this paper, Kupfer’s classical failure criterion was applied to verify the experimental data and the predicted biaxial loading on plain concrete under fixed lateral loading and was regarded as relatively conservative. Meantime, based on Kupfer’s failure criterion and octahedral stress space, two different failure criteria had been proposed and verified. The results show that the proposed failure criteria have good applicability. The failure mechanism under fixed lateral loading was discussed and compared with that under the equal proportional loading method. This research is meaningful to plain concrete engineering application and calculation.

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

Development and Engineering Application of Dry-Mixing Self-Compacting Concrete

2013 ◽  
Vol 689 ◽  
pp. 372-377
Author(s):  
Bo Yi ◽  
Yan He Li ◽  
Shi Ding
Keyword(s):  
Mechanical Properties ◽  
Engineering Application ◽  
Social Effects ◽  
Self Compacting Concrete ◽  
Ordinary Concrete ◽  
Dry Mixing ◽  
Working Performance

In this paper, the application background of ordinary concrete is introduced first, and our purpose is to research the advantages of dry-mixing self-compacting concrete relative to ordinary concrete. Some studies on mechanical properties, working performance and durability of dry-mixing self-compacting concrete are brought into this paper. The results shows that the application of dry-mixing self-compacting concrete produced economic and social effects.

scholarly journals Experimental Studies on Cracking and Local Strain Behaviors of Rock-Like Materials with a Single Hole before and after Reinforcement under Biaxial Compression

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jian Liao ◽  
Yanlin Zhao ◽  
Liming Tang ◽  
Qiang Liu
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Failure Modes ◽  
Lateral Pressure ◽  
Peak Strength ◽  
Biaxial Compression ◽  
Tensile Cracks ◽  
Fracture Surfaces ◽  
Single Hole ◽  
Aluminum Alloy Tube

In deep underground engineering, circular roadways are widely used; many rock engineering problems can usually be simplified as mechanical analysis of rock structures with holes. To reveal the influence of intrahole reinforcement on the mechanical properties of rock with a single hole, this paper takes the single-hole rock-like material specimens with different reinforcement conditions as the research object. The RYL600 rock shear rheometer was used to conduct biaxial compression tests and, combined with HD industrial cameras and high-precision strain gauges, to study the effects of different reinforcement thicknesses and different lateral pressure on the mechanical properties of single-hole rock-like materials during the total stress and strain process. The thickness of the reinforced aluminum alloy pipe in the whole test is divided into four types: 0, 1, 1.5, and 2 mm. Under different reinforcement conditions, it is divided into 4 series of 0, 0.5, 1, and 1.5 MPa according to the different lateral pressure. Research shows the following: (1) Under the same lateral pressure, as the reinforcement thickness of the aluminum alloy tube increases, the reinforcement effect of the aluminum alloy tube on the specimen increases, and the strength of the reinforced specimen is increased by 1.42%~33.04% compared with the strength of the unreinforced specimen; under the same reinforced thickness of the aluminum tube, the peak strength of the specimen increases with the increase of lateral pressure, and the peak strength of the specimen with lateral pressure is 3.34%~50.26% higher than that of the specimen without lateral pressure. (2) Increasing the lateral pressure can significantly reduce the primary tensile cracks of the specimen. As the reinforcement thickness increases, the primary tensile cracks and remote cracks of the specimen are significantly reduced, and the failure surface of the specimen gradually tends to the middle of the sample. (3) The failure modes of specimens with holes can be divided into five types: single bevel type I, single bevel type II, single bevel type III, bevel T type, and single part shear type. All of these five failure modes are shear cracks that develop into fracture surfaces, while remote cracks and primary tensile cracks do not develop into fracture surfaces.

scholarly journals Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0246815
Author(s):  
Honggang Zhao ◽  
Haitao Sun ◽  
Dongming Zhang ◽  
Chao Liu
Keyword(s):  
Mechanical Properties ◽  
Failure Mode ◽  
Failure Modes ◽  
Biaxial Stress ◽  
Tensile Fracture ◽  
Biaxial Compression ◽  
Lateral Stress ◽  
Variable Theory ◽  
Failure Characteristics ◽  
Elliptical Opening

Two kinds of common tunnel shapes, i.e. elliptical opening and square opening were selected for biaxial compression tests, and the influences of two kinds of opening shapes on the mechanical properties, failure characteristics and failure modes of sandstone were compared and analyzed. The complex variable theory and mapping functions were used to obtain the analytical stress solution around elliptical and square openings. The results show that the stability of the specimen containing an elliptical opening was better than that of the specimen containing a square opening under the same lateral stress. Compared with the elliptical opening, the local damage was formed earlier in the square opening which might be caused by a higher stress concentration around the square opening. The stress distributions around openings were influenced by the opening shape and lateral stress coefficient. The top and bottom of square opening were more prone to tensile fracture, and the distribution range of tensile was larger than that of elliptical opening. When the opening failed, the intensity of square opening failure was weaker than that of elliptical opening. On the basis of the average frequency value and the rise angle value, the failure mode of specimen containing elliptical or square opening was distinguished. It was found that the mixed tension and shear failure dominated the failure of specimens with different opening shapes, and the number of shear cracks in the specimen containing a square opening was greater than that in the specimen containing an elliptical opening. The above method of judging failure mode by acoustic emission signals was well verified by the CT images of damaged specimens.

Atomistic Molecular Dynamics Simulation Based Failure Criterion of Polycrystalline Graphene Under Biaxial Loading

2020 ◽  
Author(s):  
MD Imrul Reza Shishir ◽  
Alireza Tabarraei
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Failure Criterion ◽  
Biaxial Loading ◽  
Biaxial Tension ◽  
Chemical Vapor ◽  
Dynamics Simulation ◽  
Effect Of Temperature ◽  
Graphene Sheets ◽  
Failure Envelope

Abstract Graphene sheets produced by chemical vapor deposition (CVD) are polycrystalline and the presence of grain boundaries (GBs) alter their mechanical properties relative to single-crystal graphene. In this study, we have performed a series of molecular dynamics simulations using REBO2+S potential in order to develop a failure criterion for infinite polycrystalline graphene sheets under biaxial tension. We have studied the effect of temperature on mechanical properties of polycrystalline graphene for both uniaxial and biaxial loading conditions. The normal stresses are normalized with respect to the corresponding uniaxial ultimate strength values and the normalized stresses are used to define the failure envelope of polycrystalline graphene. Our study suggests that a bilinear failure envelope or a circular failure envelope can be used to represent with reasonable accuracy the tensile strength of polycrystalline graphene under biaxial loading at different temperatures.

scholarly journals An Experimental Study of Dynamic Compression Performance of Self-Compacting Concrete

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3731
Author(s):  
Feiting Shi ◽  
Peng Cao ◽  
Ziyu Wang ◽  
Yanan Gan ◽  
Changjun Zhou ◽  
...  
Keyword(s):  
Strain Rate ◽  
Compressive Stress ◽  
Dynamic Compression ◽  
Dynamic Performance ◽  
Compression Tests ◽  
Self Compacting Concrete ◽  
Compression Performance ◽  
Ordinary Concrete ◽  
Failure Patterns ◽  
Diagonal Crack

To investigate the dynamic performance of self-compacting concrete (SCC), the dynamic uniaxial compression tests at eight different loading strain rates were performed on the ordinary concrete and SCC cubic specimens. Based on the tests, the compression failure patterns and stress–strain curves of both kinds of concrete were obtained. The results show that SCC performs more brittle than ordinary concrete by showing the diagonal crack failure pattern of SCC at a high strain rate. Besides, with the increase of loading strain rate, the peak compressive stress of SCC is slightly lower than that of ordinary concrete, but the increase of elastic modulus is slightly higher than that of ordinary concrete. The peak compressive strains of the two kinds of concrete are discrete under the influence of loading strain rate, thus putting forward the relation equation for the loading strain rate and peak compressive stress increase coefficient of the two kinds of concrete. Besides, based on the theory of elastic–plastic damage and considering the dynamic extension of damage, the dynamic constitutive relation with good applicability between ordinary concrete and SCC was established.

scholarly journals Numerical Study of the Strength and Characteristics of Sandstone Samples with Combined Double Hole and Double Fissure Defects

2021 ◽  
Vol 13 (13) ◽  
pp. 7090
Author(s):  
Junbiao Ma ◽  
Ning Jiang ◽  
Xujun Wang ◽  
Xiaodong Jia ◽  
Dehao Yao
Keyword(s):  
Mechanical Properties ◽  
Stress Concentration ◽  
Crack Initiation ◽  
Compressive Stress ◽  
Uniaxial Compression ◽  
Failure Modes ◽  
Numerical Study ◽  
Simulation Software ◽  
Particle Flow Code ◽  
Peak Strain

To explore the failure mechanism of rock with holes and fissures, uniaxial compression tests of sandstone samples with combined double hole and double fissure defects were carried out using Particle Flow Code 2D (PFC2D) numerical simulation software. The failure behaviour and mechanical properties of the sandstone samples with combined double hole and double fissure defects at different angles were analysed, and the evolution results of the stress field and crack propagation were studied. The results show that with a decrease in fissure angle, the crack initiation stress, damage stress, elastic modulus and peak stress of the defective rock decrease, while the peak strain increases, and the brittleness of the rock is weakened. Rocks with combined double hole and double fissure defects at different angles lead to different failure modes, crack initiation positions and crack development directions. After uniaxial compression, both compressive stress and tensile stress concentration areas are produced in the defective rock, but the compressive stress concentration is of primary importance. The concentration area is mainly distributed around the holes and fissures and the defect connecting line, and the stress concentration area decreases with the decreasing fissure angle. This study can correctly predict the mechanical properties of rock with combined double hole and double fissure defects at different angles and provide a reference for actual rock engineering.

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