Effect of The Shape of Cyclic Loading on Damping Ratio at Small Strains

The damping properties of railway ballast are critical to the safe operation of trains. This study aimed to improve the damping properties of railway ballast through the addition of tire-derived aggregate (TDA) and to evaluate the effect of TDA on other properties of ballast. The damping property and other mechanical properties of ballast mixed with different contents of TDA were tested utilizing a large direct shear test (DST) under static and cyclic loading conditions. The cyclic loading test was performed in accordance with ASTM D 7499, from which the resilient interface shear stiffness and damping ratio were obtained. The results showed that TDA significantly increased the damping ratio of railway ballast, but decreased the resilient interface shear stiffness. The stress-strain behavior of the ballast-TDA mixes was obtained from the static loading test, showing that TDA significantly decreased the peak shear stress and the dilation effect. According to the Mohr-Coulomb failure criterion, TDA also decreased the cohesion strength and the internal friction angle of the ballast. Based on the test results from this study, 5% rubber is recommended for use in railway ballast.

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Failure Characteristic of Granite under Cyclic Loading with Different Frequencies

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.638-640.1967 ◽

2014 ◽

Vol 638-640 ◽

pp. 1967-1970

Author(s):

Xiao Hui Ni

Keyword(s):

Elastic Modulus ◽

Cyclic Loading ◽

Nuclear Power ◽

Damping Ratio ◽

Research Result ◽

Testing Machine ◽

Dynamic Elastic Modulus ◽

Dynamic Strain ◽

Response Analysis ◽

Cyclic Frequency

The uniaxial cyclic fatigue tests on granite coming from the ChangJiang of Hainan nuclear power first-stage construction conventional island were done on the RMT-150B multi-function automatic rigid rock servo material testing machine. Stress amplitude of 10 MPa and sine wave cyclic loads with five different frequencies of 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, and 1 Hz were adopted as dynamic disturbance. The law between cyclic frequency and dynamic stress-dynamic strain hysteretic curve, dynamic elastic modulus and damping ratio are researched. The results showed that the curves of strain and stress for loading and unloading are not superposition under cyclic loading, but hysteretic loops. When cyclic frequency changes between 0.01 and 1.0 Hz, the granite hysteretic loop area, dynamic elastic modulus and damping ratio are increased with frequency increasing. The research result offered great reference value to seismic response analysis and site safety evaluation of the changjiang nuclear power.

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Dynamic shear modulus and damping ratio of thawed saturated clay under long-term cyclic loading

Cold Regions Science and Technology ◽

10.1016/j.coldregions.2017.10.003 ◽

2018 ◽

Vol 145 ◽

pp. 93-105 ◽

Cited By ~ 13

Author(s):

Bo Lin ◽

Feng Zhang ◽

Decheng Feng ◽

Kangwei Tang ◽

Xin Feng

Keyword(s):

Cyclic Loading ◽

Shear Modulus ◽

Damping Ratio ◽

Dynamic Shear Modulus ◽

Dynamic Shear ◽

Saturated Clay

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Novel Methods for the Computation of Small-Strain Damping Ratios of Soils from Cyclic Torsional Shear and Free-Vibration Decay Testing

Geotechnics ◽

10.3390/geotechnics1020016 ◽

2021 ◽

Vol 1 (2) ◽

pp. 330-346

Author(s):

Zhongze Xu ◽

Yumeng Tao ◽

Lizeth Hernandez

Keyword(s):

Free Vibration ◽

Ambient Noise ◽

Damping Ratio ◽

Small Strain ◽

Material Damping ◽

Viscous Material ◽

Small Strains ◽

Torsional Shear ◽

Novel Methods ◽

Decay Testing

This paper illustrates two novel methods for computing the small-strain hysteretic material damping ratio, λmin, of soils from the cyclic torsional shear (TS) and computing the small-strain viscous material damping ratio, Dmin, from the free-vibration decay (FVD) testing. Both λmin and Dmin are challenging to measure, due to the significant level of ambient noise at small strains (<10−4%). A two-step method is proposed combining the Fourier Transform and a phase-based data fitting method for torsional shear testing, and this method can effectively eliminate the ambient noise at small strains. A Hilbert Transform-based method is proposed for the free-vibration decay testing in order to achieve a more accurate measurement of the viscous material damping ratio, D, at different strain levels, especially at small strains. The improved λmin and Dmin at small strains are compared to data available in the literature. The two novel methods are shown to be accurate in computing the small-strain damping ratios.

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Dynamics of Biochar-Silty Clay Interaction Using In-House Fabricated Cyclic Loading Apparatus: A Case Study of Coastal Clay and Novel Peach Biochar from the Qingdao Region of China

Sustainability ◽

10.3390/su12072599 ◽

2020 ◽

Vol 12 (7) ◽

pp. 2599 ◽

Cited By ~ 3

Author(s):

Junwei Liu ◽

Suriya Prakash Ganesan ◽

Xin Li ◽

Ankit Garg ◽

Aman Singhal ◽

...

Keyword(s):

Cyclic Loading ◽

Shear Modulus ◽

Dynamic Behavior ◽

Void Ratio ◽

Water Pressure ◽

Damping Ratio ◽

Cyclic Strength ◽

Silty Clay ◽

Amended Soils ◽

Amended Soil

Biochar has been recently investigated as an eco-friendly material in bio-engineered slopes/landfill covers. A majority of recent studies have focused on analyzing water retention behavior while very few have examined dynamic behavior (i.e., cyclic loading due to earthquake, wind, or wave) of biochar amended soil. As far as the authors are aware, there is no study on the dynamic behavior of biochar amended soils. Considering the above mentioned study as a major objective, field excavated soil was collected and mixed with in-house produced biochar from peach endocarps, at three amendment rates (5%, 10%, and 15%). The un-amended bare soil and biochar amended soil were imposed to a cyclic load in a self-designed apparatus and the corresponding stress-strain parameters were measured. Dynamic parameters such as shear modulus and damping ratio were computed and the results were compared between bare and biochar amended soil. Furthermore, the residual cyclic strength of each soil types were correlated with an estimated void ratio to understand the interrelation between dynamic loading responses and biochar amended soils. The major outcomes of this study show that the addition of biochar decreases the void ratio, thereby increasing the shear modulus and residual cyclic strength. However, the modulus and strength values attenuates after 15 cycles due to an increase in pore water pressure. In contrary, at higher amendment rates, Biochar Amended Soils (BAS) forms clay-carbon complex and decreases both shear modulus and residual cyclic strength.

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Restoring Force Model of an Energy-Dissipation Joint in Hybrid Frames: Simplified Skeleton Curve and Hysteretic Rules

Advances in Civil Engineering ◽

10.1155/2020/7806381 ◽

2020 ◽

Vol 2020 ◽

pp. 1-18

Author(s):

Yanhua Wang ◽

Yan Feng ◽

Dongsheng Huang ◽

Zirui Huang ◽

Zhongfan Chen

Keyword(s):

Energy Dissipation ◽

Cyclic Loading ◽

Critical Points ◽

Damping Ratio ◽

Force Model ◽

Restoring Force ◽

Theoretical Derivation ◽

Skeleton Curve ◽

Restoring Force Model ◽

The Moment

In this paper, a restoring force model, composed of a trilinear skeleton curve and hysteretic rules, is proposed based on nine pseudostatic tests of the energy-dissipation joint under horizontal low cyclic loading. The critical points of the simplified skeleton curve are obtained via theoretical derivation and FE simulation. The hysteretic rules for the joints are simplified as a concave hexagon, where the parameters of the critical points are optimized by the genetic algorithm (GA). Using the established trilinear skeleton curve, three different working stages, i.e., elastic, hardening, and softening, were divided by the critical points and the moment stiffness of three stages can be calculated. The proposed hysteretic rules of each stage can reveal and explain the “pinching” in the cyclic loading, which make it easier to understand the mechanism of the energy-dissipation joint. The comparison between the restoring force model and the tests shows that the simplified skeleton curves, the established hysteretic rules, and the ductility and the damping ratio are consistent with the experimental results. Finally, the effectiveness of the established restoring force model is verified.

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Shear modulus and damping ratio of a clay during undrained cyclic loading

Géotechnique ◽

10.1680/geot.2001.51.5.467 ◽

2001 ◽

Vol 51 (5) ◽

pp. 467-470 ◽

Cited By ~ 11

Author(s):

S. Teachavorasinskun ◽

P. Thongchim ◽

P. Lukkunaprasit

Keyword(s):

Cyclic Loading ◽

Shear Modulus ◽

Damping Ratio

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Comparisons of deformation characteristics of rockfill materials using monotonic and cyclic loading laboratory tests and in situ tests

Canadian Geotechnical Journal ◽

10.1139/t94-022 ◽

1994 ◽

Vol 31 (2) ◽

pp. 162-174 ◽

Cited By ~ 17

Author(s):

Nario Yasuda ◽

Norihisa Matsumoto

Keyword(s):

Cyclic Loading ◽

Laboratory Test ◽

Laboratory Tests ◽

Shear Test ◽

Triaxial Tests ◽

Deformation Characteristics ◽

Simple Shear Test ◽

Small Strains ◽

Rockfill Materials

The deformation characteristics of rockfill materials at very small strains were investigated by comparing the results of monotonic and cyclic loading laboratory tests with geophysical P- and S-wave logging data from the field. Using a precision linear variable differential transformer for displacement, the elastic moduli of rockfill materials at very small strains were measured in monotonic and cyclic loading triaxial tests. The laboratory test results agreed well with the field results. The shear moduli of rockfill materials from both a monotonic loading torsional simple shear test and a cyclic loading torsional simple shear test also showed good correspondence. Furthermore, the shear modulus predicted from the in situ shear wave tests in rockfill dams corresponded reasonably well with the modulus in the large-scale triaxial tests in the laboratory. Key words : deformation characteristics, embankment dams, rockfill materials, laboratory test, in situ test.

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Fracture Characteristics and Fatigue Damage of Noncoplanar Fractured Rocklike Specimens under Uniaxial Graded Cyclic Loading and Unloading

Geofluids ◽

10.1155/2021/9993195 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Gui-cheng He ◽

Wen-yuan Wu ◽

Yun Wang ◽

Yong-ming Xue ◽

Bing Dai ◽

...

Keyword(s):

Elastic Modulus ◽

Energy Dissipation ◽

Cyclic Loading ◽

Hysteresis Loop ◽

Fatigue Damage ◽

Damping Ratio ◽

Fracture Characteristics ◽

Cyclic Loading And Unloading ◽

Loading And Unloading ◽

Limit Stress

To study the fracture characteristics and fatigue damage of fractured rock masses, noncoplanar fractured rocklike specimens prepared using cement mortar were used for a graded cyclic loading–unloading test. The results showed that the two ends of the horizontal crack were the main stress concentration areas, and they inhibited crack initiation of the inclined fracture. With increasing crack inclination, the inhibitory effect became more obvious. Under the condition that the lower limit stress is constant, as the upper limit stress increases, energy dissipation of the specimen increases, becoming relatively stable in each stage of the cycle. With increasing crack inclination, the increase in the energy dissipation value decreases. Specimens with large changes in the shape of their hysteresis loop tend to exhibit large fluctuations in the elastic modulus. As the loading progressed, the elastic modulus exhibited a downward trend, and the damping ratio tended to be stable. The change in the damping ratio is affected by the dynamic elastic modulus and area of the hysteresis loop. Based on the Weibull probability distribution function, the evolution curve of the damage variable of the specimen can be obtained. This curve reflects the trend of the damage change of the rocklike specimens under various levels of cyclic loading and unloading.

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