scholarly journals Investigation of the Mechanical Behavior of Polypropylene Fiber-Reinforced Red Clay

2021 ◽  
Vol 11 (22) ◽  
pp. 10521
Author(s):  
Jia Liu ◽  
Xi’an Li ◽  
Gang Li ◽  
Jinli Zhang
Keyword(s):  
Shear Strength ◽  
Polypropylene Fiber ◽  
Strain Curve ◽  
Triaxial Tests ◽  
High Water Content ◽  
Hyperbolic Model ◽  
High Plasticity ◽  
Fiber Reinforced ◽  
Red Clay ◽  
Stress Strain

Red clay is not easy to use as a natural foundation because of its high water content, high plasticity index, large void ratio, and susceptibility to shrinkage and cracking. In this study, consolidated undrained triaxial tests were conducted to examine the mechanical properties of polypropylene fiber-reinforced red clay and to analyze the influence of the fiber content (FC), fiber length (FL), and cell pressure on its shear strength. By performing a regression analysis on the test data, a hyperbolic constitutive model that considers the influence of FC, FL, and cell pressure was established, and a method was developed to estimate the parameters of the model. The findings show that, in contrast with the nonreinforced red clay, the fiber-reinforced red clay had a stress-strain curve characterized by typical strain hardening, with the shear strength increasing with FC, FL and cell pressure. The calculated results of the model coincide with the test results well, confirming that the hyperbolic model could appropriately describe the stress-strain relationship of polypropylene fiber-reinforced red clay and have reference value for the design and construction of fiber-reinforced red clay foundations.

Polypropylene Fiber Reinforced Concrete for Airfield Pavements:Modeling of Stress-Strain Curve Under Compression

2011 ◽  
Vol 261-263 ◽  
pp. 171-177
Author(s):  
Tammam Merhej ◽  
De Cheng Feng
Keyword(s):  
Reinforced Concrete ◽  
Analytical Model ◽  
Volume Fraction ◽  
Polypropylene Fiber ◽  
Strain Curve ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Polypropylene Fiber Reinforced Concrete

An analytical model for compressive stress-strain curve of polypropylene fiber reinforced concrete (PPFRC) was proposed. The polypropylene fiber used was 60-mm long twisted fiber with aspect ratio of 120. The fiber was added in three volume fractions 0.2%, 0.4% and 0.6%. Tow concrete mixtures with varying water-cement ratio were used. The accuracy of the proposed model was evaluated by comparing the area under stress-strain curves for experimental and analytical model. The results showed good agreement between the experimental and analytical curves. In addition; empirical equations were proposed to quantify the effect of polypropylene fiber on compressive strength, strain at peak stress, and toughness of concrete in terms of fiber volume fraction.

Basalt fiber reinforced porous aggregates-geopolymer based cellular material

2015 ◽  
Vol 08 (01) ◽  
pp. 1550005 ◽  
Author(s):  
Xin Luo ◽  
Jin-Yu Xu ◽  
Weimin Li
Keyword(s):  
Basalt Fiber ◽  
Strain Curve ◽  
Civil Defense ◽  
Cellular Material ◽  
High Plasticity ◽  
Fiber Reinforced ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Energy Absorbing ◽  
The Ideal

Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress–strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress–strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.

Stiffness degradation and shear strength of silty sands

2004 ◽  
Vol 41 (5) ◽  
pp. 831-843 ◽  
Author(s):  
Junhwan Lee ◽  
Rodrigo Salgado ◽  
J Antonio H Carraro
Keyword(s):  
Shear Strength ◽  
Nonlinear Behavior ◽  
Triaxial Tests ◽  
Hyperbolic Model ◽  
Soil Behavior ◽  
Cone Penetration ◽  
Stress Strain ◽  
Early Loading ◽  
Realistic Representation ◽  
Strain Relationship

Soils behave nonlinearly from very early loading stages. When granular soils contain a certain amount of fines, the degree of nonlinearity also changes, as stiffness and strength characteristics vary with fines content. Hyperbolic stress–strain models and variations of these models are often used for description of the nonlinear behavior. A modified hyperbolic stress–strain relationship is used in this paper for representing the degradation of the elastic modulus of silty sands. The model is based on two modulus degradation parameters that determine the magnitude and rate of modulus degradation as a function of stress level. Realistic representation of soil behavior using this nonlinear relationship requires estimation of the degradation parameters as a function of silt content and relative density DR. A series of triaxial test results on sands containing different amounts of nonplastic silt were analyzed with this purpose. Relationships between the degradation parameters and cone penetration test (CPT) cone resistance qc are also proposed.Key words: hyperbolic model, silty sands, triaxial tests, modulus degradation, stress–strain response, shear strength, Gmax.

Behavior and modeling of post-heated circular concrete specimens repaired with fiber-reinforced polymer composites

2021 ◽  
pp. 136943322110585
Author(s):  
Seyed Mehrdad Elhamnike ◽  
Rasoul Abbaszadeh ◽  
Vahid Razavinasab ◽  
Hadi Ziaadiny
Keyword(s):  
Strain Curve ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Concrete Members ◽  
Frp Composites ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites

Exposure of buildings to fire is one of the unexpected events during the life of the structure. The heat from the fire can reduce the strength of structural members, and these damaged members need to be strengthened. Repair and strengthening of concrete members by fiber-reinforced polymer (FRP) composites has been one of the most popular methods in recent years and can be used in fire-damaged concrete members. In this paper, in order to provide further data and information about the behavior of post-heated circular concrete columns confined with FRP composites, 30 cylindrical concrete specimens were prepared and subjected under four exposure temperatures of 300, 500, 700, and 900. Then, specimens were repaired by carbon fiber reinforced polymer composites and tested under axial compression. Results indicate that heating causes the color change, cracks, and weight loss of concrete. Also, with the increase of heating temperature, the shape of stress–strain curve of FRP-retrofitted specimens will change. Therefore, the main parts of the stress–strain curve such as ultimate stress and strain and the elastic modulus will change. Thus, a new stress–strain model is proposed for post-heated circular concrete columns confined by FRP composites. Results indicate that the proposed model is in a good agreement with the experimental data.

scholarly journals Three-dimensional numerical simulation of mechanical properties of soil-tire mixture by discrete element method

2019 ◽  
Vol 92 ◽  
pp. 14011
Author(s):  
Mohsen Asadi ◽  
Ahmad Mahboubi
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Damping Ratio ◽  
Strain Curve ◽  
Young Modulus ◽  
Engineering Properties ◽  
Triaxial Tests ◽  
Sand Particle ◽  
Arithmetic Average ◽  
Harmonic Average

Soil engineering properties can be improved employing different methods. Among them is mixing soil with tire derived additives (TDA). TDAs generally increase some parameters of mixture such as damping ratio, permeability, ductility and also in some cases shear strength. Various properties of TDAs from mechanical properties to their geometry can affect the mixture behavior. In this paper using the YADE platform, simulations of triaxial tests on sand tire mixtures are presented. To take compressibility into consideration, each rubber crumb particle is made of several spheres connected elastically to each other. For sand particle generation the clump technique was employed. Shapes of both sand and rubber particles are inspired from real grains. As properties of sand and rubber are different, especially Young modulus, rubber sand interaction is considered as soft rigid contact. Therefor harmonic average and arithmetic average was used to compute contact Young modulus (and then stiffness). The model was validated by comparison of results of triaxial tests simulation on pure rubber sample with literature ones which both exhibited linear stress-strain curve. Then triaxial tests with different sand to rubber ratio were simulated to see whether harmonic average or arithmetic average gives the best match to literature. The results show shear strength reduces by decreasing of sand to rubber ratio. This is the same as what is reported in literature.

A Characteristic and a Precisely Constitutive Model for Undrained Clay

2020 ◽  
Vol 975 ◽  
pp. 203-207
Author(s):  
Shih Tsung Hsu ◽  
Wen Chi Hu ◽  
Yu Heng Lin ◽  
Zhuo Ling
Keyword(s):  
Shear Strength ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Strain Hardening ◽  
Undrained Shear Strength ◽  
Triaxial Tests ◽  
Stress Strain ◽  
Proposed Model ◽  
Taipei Basin ◽  
Undrained Shear

Constitutive models for soils are usually adopted in numerical method to analyze the behavior of geotechnical structures. This study performs a series of consolidated-undrained triaxial tests to establish the stress-strain curve of clay. A constitutive model that considers continuous strain hardening-softening is proposed based on the results of triaxial tests. Triaxial test results reveal that undrained shear strength linearly increases with an increase in consolidated pressure , the normalized undrained shear strength is about 0.52 not only for this study but also for the other two cases around Taipei Basin. Due to undrained condition, an associated flow rule between plastic strain increment and stress tensor is adopted. As accumulative plastic strain or/and consolidated pressure change, the mobilized undrained shear strength also changes. All parameters needed for the proposed model can be expressed as a function of undrained shear strength Su, The mobilized undrained shear strength for the proposed model during strain hardening-softening can be in term of accumulative plastic strain. This model can calculate the stress-strain curves of clayed soils accurately.

Duncan-Chang Nonlinear Elastic Model Considered Loess Structure

2011 ◽  
Vol 90-93 ◽  
pp. 176-181
Author(s):  
Chang Lu Chen ◽  
Sheng Jun Shao ◽  
Lin Ma
Keyword(s):  
Nonlinear Model ◽  
Stress Ratio ◽  
Structural Parameters ◽  
Strain Curve ◽  
Triaxial Tests ◽  
Model Parameters ◽  
Elastic Model ◽  
Stress Strain ◽  
Nonlinear Elastic ◽  
Intact Loess

Duncan-Chang nonlinear model has been modified and applied to the structural loess calculation. Based on structural studies and conventional triaxial tests, this paper has analyzed the mechanical properties of intact loess and the relationship between the stress ratio structural parameters and the strain, then the expression of generalized shear strain and stress ratio structural parameters are given to facilitate the engineering applications. On this basis, the stress-strain curve of intact loess was corrected by the use of the stress ratio structural parameters. The form of the intact loess stress-strain curves which have been revised has changed hardening from the softening or weak softening. The results show that the modified stress-strain curves of intact loess can apply Duncan- Chang nonlinear model to calculate and the model parameters are reasonable and effective. This method provides Duncan-Chang nonlinear model which is widely used in engineering with a new ways and means in intact structural loess application.

scholarly journals Comparison of Mechanical Properties of Fiber-Reinforced Sand under Triaxial Compression and Direct Shear

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Reza Noorzad ◽  
Seyed Taher Ghoreyshi Zarinkolaei
Keyword(s):  
Shear Strength ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Polypropylene Fiber ◽  
Triaxial Tests ◽  
Direct Shear ◽  
Test Results ◽  
Peak Reduction ◽  
Shear Tests ◽  
Direct Shear Tests

AbstractThis research investigates the behavior of sand reinforced with polypropylene fiber. To do this, 40 direct shear tests and 40 triaxial tests were performed on the coastal beaches of Babolsar, a city in the North of Iran. The effect of parameters such as fiber content, length of fiber and normal or confining pressure on the behavior of Babolsar sand have been studied. In this study, four various fiber contents (0, 0.25, 0.5 and 1 percent), three different lengths of fiber (6, 12 and 18 mm) and four normal or confining pressures (50, 100, 200 and 400 kPa) have been employed. The test results show that fiber inclusion has a significant effect on the behavior of sand. In both direct shear and triaxial tests, the addition of fibers improved shear strength parameters (C, '), increased peak shear strength and axial strain at failure, and also limited the amount of post-peak reduction in shear resistance. The comparison of the test results revealed that due to better fiber orientation toward the direction of principal tensile strain in triaxial test as compared to direct shear tests, the fiber efficiency and its effect on soil behavior is much more significant in triaxial specimens.

scholarly journals Experimental Investigation on Shear Strength and Liquefaction Potential of Rubber-Sand Mixtures

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Zhou Enquan ◽  
Wang Qiong
Keyword(s):  
Shear Strength ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Construction Materials ◽  
Horizontal Displacement ◽  
Triaxial Tests ◽  
Hyperbolic Model ◽  
Liquefaction Potential ◽  
Direct Shear Tests ◽  
Rubber Particles

The application of scrap tires as construction materials in civil engineering is one of the most promising ways to recycle this pollutant. The objective of this study was to investigate the shear strength and liquefaction potential of saturated rubber-sand mixtures. Direct shear tests and cyclic triaxial tests were conducted on rubber-sand mixtures at various rubber contents. It was found that the addition of rubber particles to sand changed the shear stress-horizontal displacement development. The addition of rubber particles to sand improved the shear strength slightly and improved resistance to liquefaction significantly. Additionally, a hyperbolic model was proposed to describe the pore water pressure generation. This study demonstrates the effect of rubber particles on the physical properties of sand.

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