ANALYSIS OF DYNAMIC STRESS-STRAIN RELATIONSHIP OF LOESS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5559-5565
Author(s):  
HONGJIAN LIAO ◽  
ZHIGANG ZHANG ◽  
CHUNMING NING ◽  
JIAN LIU ◽  
LI SONG
Keyword(s):  
Residual Strain ◽  
Dynamic Stress ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Constitutive Relationship ◽  
Triaxial Tests ◽  
Stress And Strain ◽  
Test Results ◽  
Relationship Model ◽  
Strain Relationship

This paper aims to study dynamic properties of loess. This study is helpful to the subject on how to avoid or decrease the seismic disasters on loess ground. Dynamic triaxial tests are carried out with saturated remoulded soil samples taken form loess sites in Xi'an, China. Dynamic stress and strain relationship as well as the rule of the accumulated residual strain are obtained from the test results. Linear relationship between accumulated residual strain and vibration circle under constant amplitude circular loading is presented. A hypothesis about the accumulated residual strain is proposed. 1D dynamic constitutive relationship model which can well describe the real relationship between dynamic stress and strain under irregular dynamic loading is established. Numerical program with this model is developed and an example is tested. Numerical results of hysteresis loop, accumulated residual strain, amplitude of dynamic stress and damping ratio show good agreement with test results. It is indicated that the hypothesis of accumulated residual strain and the 1D dynamic constitutive relationship model can accurately simulate the dynamic triaxial tests of saturated remoulded loess.

scholarly journals Empirical Method for Evaluating Resilient Modulus of Saturated Silty Clay under Cyclic Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhen Zhang ◽  
Yong Chen ◽  
Guanbao Ye ◽  
Peilin Xiang ◽  
Yan Xiao ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Stress Ratio ◽  
Resilient Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Empirical Method ◽  
Traffic Load ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Test Results

Resilient modulus of soil is crucial for the design of a structure on a foundation subjected to a cyclic loading (e.g., traffic load or machine vibration load). This paper conducted a series of dynamic triaxial tests of saturated silty clay, considering the influence of the factors of cyclic stress ratio (CSR), static deviatoric stress ratio (SDR), and overconsolidation ratio (OCR) on the resilient modulus and dynamic damping ratio of the soil. A cyclic loading with a form of half sine wave was used to model the traffic loading. The results showed that the soil was prone to failure under a higher SDR, even though the applied CSR was less than the critical CSR. The saturated silty clay performed a strain softening behavior and its dynamic properties deteriorated significantly when higher CSR and SDR and lower OCR were involved. Based on the test results, an empirical method with a form of exponential function was proposed to evaluate the resilient modulus of the soil, considering the combined effects of CSR and SDR and OCR. The proposed method was verified through a comparison with the test results in this study and from literatures, and some recommendations for its application were offered.

scholarly journals Multi-Scale Study of The Small-Strain Damping Ratio of Fiber-Sand Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2476
Author(s):  
Haiwen Li ◽  
Sathwik S. Kasyap ◽  
Kostas Senetakis
Keyword(s):  
Dynamic Properties ◽  
Wide Spectrum ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Small Strain ◽  
Treatment Method ◽  
Fiber Content ◽  
Polypropylene Fibers ◽  
Test Results ◽  
Fiber Reinforced

The use of polypropylene fibers as a geosynthetic in infrastructures is a promising ground treatment method with applications in the enhancement of the bearing capacity of foundations, slope rehabilitation, strengthening of backfills, as well as the improvement of the seismic behavior of geo-systems. Despite the large number of studies published in the literature investigating the properties of fiber-reinforced soils, less attention has been given in the evaluation of the dynamic properties of these composites, especially in examining damping characteristics and the influence of fiber inclusion and content. In the present study, the effect of polypropylene fiber inclusion on the small-strain damping ratio of sands with different gradations and various particle shapes was investigated through resonant column (macroscopic) experiments. The macroscopic test results suggested that the damping ratio of the mixtures tended to increase with increasing fiber content. Accordingly, a new expression was proposed which considers the influence of fiber content in the estimation of the small-strain damping of polypropylene fiber-sand mixtures and it can be complementary of damping modeling from small-to-medium strains based on previously developed expressions in the regime of medium strains. Additional insights were attempted to be obtained on the energy dissipation and contribution of fibers of these composite materials by performing grain-scale tests which further supported the macroscopic experimental test results. It was also attempted to interpret, based on the grain-scale tests results, the influence of fiber inclusion in a wide spectrum of properties for fiber-reinforced sands providing some general inferences on the contribution of polypropylene fibers on the constitutive behavior of granular materials.

A Study on Dynamic Properties of Cement-Stabilized Soils

2011 ◽  
Vol 243-249 ◽  
pp. 2050-2054 ◽  
Author(s):  
Pei Hsun Tsai ◽  
Sheng Huoo Ni
Keyword(s):  
Shear Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Test Results ◽  
Resonant Column Test ◽  
Stabilized Soil ◽  
Shearing Strain ◽  
Relationship Of ◽  
The Relationship

In this paper the dynamic property (shear modulus and damping ratio) of cement-stabilized soil is studied with using the resonant column test. The amount of cement admixed, the magnitude of confining pressure, and shearing strain amplitude are the parameters considered. Test results show that the maximum shear modulus of cement-stabilized soil increases with increasing confining pressure, the minimum damping ratio decreases with increasing confining pressure. The shear modulus of cement-stabilized soil decreases with increasing shearing strain while the damping ratio increases with increasing shearing strain. In the paper the relationship of shear modulus versus shearing strain is fitted into the Ramberg-Osgood equations using regression analysis.

scholarly journals Static and Dynamic Properties and Temperature Sensitivity of Emulsified Asphalt Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Bin Huang ◽  
Yuting Zhang ◽  
Tian Qi ◽  
Hongxing Han
Keyword(s):  
Temperature Sensitivity ◽  
Asphalt Concrete ◽  
Dynamic Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Great Influence ◽  
Temperature Control System ◽  
Stress Strain ◽  
Strain Relationship ◽  
Emulsified Asphalt

Asphalt concrete is a typical rheological material, which is hard brittle at low temperature and reflects soft plastic facture at high temperature; the temperature has a great influence on the mechanical properties of asphalt concrete. In order to eliminate the environmental pollution caused by hot asphalt construction, cationic emulsified asphalt can be used. This paper transforms the temperature control system for static and dynamic triaxial test equipment, which has achieved static and dynamic properties of emulsified asphalt concrete under different temperatures, and researched the temperature sensitivity of emulsified asphalt concrete materials including static stress-strain relationship, static strength, dynamic modulus of elasticity, damping ratio, and so on. The results suggest that (1) temperature has a great influence on the triaxial stress-strain relationship curve of the asphalt concrete. The lower the temperature, the greater the initial tangent modulus of asphalt concrete and the higher the intensity; the more obvious the softening trend, the smaller the failure strain of the specimen and the more obvious the extent of shear dilatancy. When the temperature is below 15.4°C, the temperature sensitivity of the modulus and strength is stronger significantly. (2) With the temperature rising, the asphalt concrete gradually shifts from an elastic state to a viscoelastic state, the dynamic modulus gradually reduces, and the damping ratio increases. When the temperature is above 15.4°C, the temperature sensitivity is obviously stronger for the dynamic elastic modulus and damping ratio. (3) The static and dynamic properties of asphalt concrete are very sensitive to the temperature. The test temperature should be made clear for the static and dynamic tests of asphalt concrete. The specimen temperature and the test ambient temperature must be strictly controlled.

scholarly journals Dynamic Behavior and Constitutive Relationship of Mudstone Slip Zone of Landslide with Weak Interlayer

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jingjing Zhou ◽  
Fasuo Zhao ◽  
Yanbo Zhu ◽  
Wenqi Dong ◽  
Ziguang He
Keyword(s):  
Elastic Modulus ◽  
Dynamic Behavior ◽  
Empirical Model ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Damping Ratio ◽  
Constitutive Relationship ◽  
Dynamic Elastic Modulus ◽  
Loading Frequency ◽  
Mountain Area

Sliding zone dynamics in the Qinling-Daba mountain area under different dynamic parameters have not been studied extensively. In this study, we investigated the dynamic behavior of the sliding zones of a high-steep rock landslide in the Qinling-Daba mountain area under the influence of dynamic stress amplitude and frequency and proposed an empirical model of the dynamic constitutive relationship. The dynamic behavior was studied based on a cyclic triaxial test system. The results indicated that an increase in the dynamic stress amplitude decreased the dynamic elastic modulus linearly, increased the damping ratio, and increased the axial strain exponentially. Among these properties, the elastic strain was found to be more sensitive to the increase in the dynamic stress amplitude than the plastic strain. As the loading frequency increased, the dynamic elastic modulus increased, whereas the damping ratio decreased. Furthermore, the proposed empirical model of the dynamic constitutive relationship between the vibration number and loading frequency based on the dynamic elastic modulus could satisfactorily describe the dynamic stress-strain relationships of the samples from test stability and failure zones. These findings are expected to make a significant contribution toward further revealing the sliding mechanism of such landslides.

scholarly journals Enhancing Vibration Reduction on Lightweight Lower Control Arm

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Alessandro Messana ◽  
Alessandro Ferraris ◽  
Andrea G. Airale ◽  
Alessandro Fasana ◽  
Massimiliana Carello
Keyword(s):  
Mechanical Performance ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Vibration Reduction ◽  
Design Procedure ◽  
Test Results ◽  
Hybrid Lca ◽  
Original Solution ◽  
Lower Control Arm ◽  
Real Behavior

This paper describes the design procedure to enhance the damping properties of a multimaterial lightweight suspension arm for a C-segment vehicle. An innovative viscoelastic material has been used to join carbon fiber with steel that has a function of passive constrained layer damper and adhesive simultaneously. Therefore, the hybrid technology applied has been focused on reducing the LCA mass, diminishing the steel thickness, and adding a CFRP tailored cover without compromising the global mechanical performance. Particular attention has been paid to the investigation of the dynamic response in terms of vibration reduction, especially in the range of structure-borne frequencies of 0–600 Hz. Two different viscoelastic materials have been evaluated in such a way to compare their stiffness, damping, and dynamic properties. The experimental test results have been virtually correlated with a commercial FEM code to create the respective material card and predict the real behavior of the LCAs (original and hybrid). The experimental modal analysis has been performed and compared on both the arms highlighting a very good correlation between virtual and experimental results. In particular, the hybrid LCA allows an interesting improvement of damping ratio, about 3,5 times higher for each eigenmode than in the original solution.

scholarly journals Laboratory Characterization of a Compacted–Unsaturated Silty Sand with Special Attention to Dynamic Behavior

2020 ◽  
Vol 10 (7) ◽  
pp. 2559
Author(s):  
Andrzej Głuchowski ◽  
Zdzisław Skutnik ◽  
Marcin Biliniak ◽  
Wojciech Sas ◽  
Diego Lo Presti
Keyword(s):  
Shear Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Bender Element ◽  
State Dependent ◽  
Laboratory Characterization ◽  
Dynamic Excitations

The dynamic properties of compacted non-cohesive soils are desired not only because of the risk of natural sources of dynamic excitations such as earthquakes, but mostly because of the anthropogenic impact of machines that are working on such soils. These soils are often unsaturated, which positively affects the soil’s mechanical properties. The information about the values of these parameters is highly desirable for engineers. In this article, we performed a series of tests, including oedometric tests, resonant column tests, bender element tests, and unsaturated triaxial tests, to evaluate those characteristic parameters. The results showed that sandy silt soil has a typical reaction to dynamic loading in terms of shear modulus degradation and the damping ratio curves’ characteristics, which can be modeled by using empirical equations. We found that the compaction procedure caused an over-consolidation state dependent on the moisture content during compaction effort. The article analyzed the soil properties that impact the maximum shear modulus G0 value. Those properties were suction s, confining pressure σ3, and compaction degree represented by the void ratio function f(e).

scholarly journals A Stress-Strain Model for Brick Prism under Uniaxial Compression

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Keun-Hyeok Yang ◽  
Yongjei Lee ◽  
Yong-Ha Hwang
Keyword(s):  
Strain Curve ◽  
Peak Stress ◽  
Test Results ◽  
Compression Tests ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Proposed Model ◽  
Relationship Model ◽  
Strain Relationship ◽  
Strain Model

This study proposes a simple and rational stress-strain relationship model applicable to brick masonry under compression. The brick prism compression tests were conducted with different mortar strengths and with constant brick strength. From the observation of the test results, shape of the stress-strain curve is assumed to be parabola. In developing the stress-strain model, the modulus of elasticity, the strain at peak stress, and the strain at 50% of the peak stress on the descending branch were formulated from regression analysis using test data. Numerical and statistical analyses were then performed to derive equations for the key parameter to determine the slopes at the ascending and descending branches of the stress-strain curve shape. The reliability of the proposed model was examined by comparisons with actual stress-strain curves obtained from the tests and the existing model. The proposed model in this study turned out to be more accurate and easier to handle than previous models so that it is expected to contribute towards the mathematical simplicity of analytical modeling.

scholarly journals Effect of Sand Fouling on the Dynamic Properties and Volume Change of Gravel During Cyclic Loadings

2020 ◽  
Author(s):  
Meysam Bayat
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Dynamic Behavior ◽  
Volume Change ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Practical Applications ◽  
Large Shear Strain

Understanding the factors that influence the dynamic behavior of granular soils during cyclic loading is critical to infrastructure design. Previous research has lacked quantitative study of the effects of fouling index (FI), mean effective confining pressure, relative density, shear strain level and anisotropic consolidation, especially when the effective vertical stress is lower than the effective horizontal stress on the dynamic behavior of gravelly soils. The objective of the present study was to evaluate the dynamic behavior and volume change of both clean and fouled specimens for practical applications. To this end, cyclic triaxial tests with local strain measurements under both isotropic and anisotropic confining conditions were conducted. It is found that the fouled specimen with 50 % sand (i.e. the specimen which contains 50 % gravel and 50 % sand) has the highest shear modulus at low shear strain levels and the largest volume reduction and damping ratio at large shear strain levels. The results of tests indicate that the effect of fouling index on the shear modulus is reduced at large shear strain levels. Volumetric contraction due to the increase in mean effective confining pressure is more significant at large shear strain levels. The results also indicate that the stiffness of the specimens under anisotropic compression mode are larger than those in extension or isotropic mode.

Experimental Study on Lateral Stiffness and Dynamic Properties of Steel Drive-in Storage Racks

2013 ◽  
Vol 351-352 ◽  
pp. 730-733
Author(s):  
Bo Cheng ◽  
Zhen Yu Wu
Keyword(s):  
Load Transfer ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Single Point ◽  
Lateral Stiffness ◽  
Test Results ◽  
Static Test ◽  
Vibration Tests ◽  
Storage Racks ◽  
Deformation Modes

The static and free vibration tests were carried out to investigate the initial lateral stiffness and dynamic properties of steel drive-in storage racks. The bracing configuration and friction between pallets and rail beams were taken into consideration. The static test results indicate that the tested storage racks show sideways and torsional deformation modes under the single-point horizontal force. Both top plan bracings and back spine bracings can change the load transfer through the rack framework, strengthen the initial lateral stiffness of racks, but only back spine bracings can affect the natural frequency and damping ratio of racks. The friction force between pallets and rail beams makes pallets act as links to connect adjacent rack columns, so the pallets are beneficial factors to increase the lateral stiffness of storage racks. Compared with unload racks, the natural frequencies of loaded racks are smaller.

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