• Journal of the Korean Geotechnical Society
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• v.33 no.3
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• pp.5-15
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• 2017

In this study, the liquid and plastic limit tests were conducted on Paju clay with Casagarande method (dynamic) and the fall cone test method (static) to find out the effects of test methods and testers on their values. Six testers, who already have the experience of test, participated. As a results of liquid limit tests, the fall cone test method showed 4% smaller liquid limit compared to the value determined by Casagrande method. As the number of tests increased, the fall cone test method showed less variation between testers and the variation range of level of proficiency was also more stable. In the case of one point method, the liquid limit determined by the fall cone test method varied with smaller range compared to the Casagrande. Consequently, the fall cone test provided more stable liquid limit value than that of Casagrande method. For the results of plastic limit tests, there were no difference between Casagrande method and the fall cone test unlike liquid limit test results. In other words, both methods showed that plastic limit reached the average value as the number of tests increased, and the tendency level of proficiency also showed to get better.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1329-1335
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• 2011

On the basis of detailed 3D finite-element (FE) limit analyses, the plastic limit load solutions for pipes with slanted circumferential through-wall cracks (TWCs) subjected to axial tension, global bending, and internal pressure are reported. The FE model and analysis procedure employed in the present numerical study were validated by comparing the present FE results with existing solutions for plastic limit loads of pipes with idealized TWCs. For the quantification of the effect of slanted crack on plastic limit load, slant correction factors for calculating the plastic limit loads of pipes with slanted TWCs from pipes with idealized TWCs are newly proposed from extensive 3D FE calculations. These slant-correction factors are presented in tabulated form for practical ranges of geometry and for each set of loading conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.68-79
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• 2018

An examination of the characteristics of the ground material in is very important in a ground investigation. Casagrande classified soil using the material properties of soils. The liquid-plastic limit test is useful for obtaining basic information of soil, and is an effective method for classifying silt and clay, as well as the material properties, such as shear strength, shrinkage, and expansion. Unlike the liquid limit test, the plasticity limit test is due to the ambiguity of the test procedure. Many geotechnical engineers and scholars have questioned the test results. In this study, a new plasticity limit method was used to compare with the thread rolling method with kaolinite, ilite and bentonite at a certain ratio, and samples were collected from the west coast of Korea. As a result of the comparison, the test value of the new test method showed high reproducibility because the error range of the test value of the conventional thread rolling test was only 10% but the error range of the new test values decreased to 2%. The difference in the slope of the existing plasticity test values was 0.1519 ~ 0.1925, and the results of the test were similar or coincided with each other. Aone - point method was proposed to make it easier to apply the new test method.

• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.73-84
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• 2013

When a slope failure or a debris flow occurs, a shear strength on failure plane becomes nearly zero and soil begins to flow like a non-cohesive liquid. A consistency of cohesive soils changes as a water content increases. Even a cohesive soil existing at liquid limit state has a small amount of shear strength. In this study, a water content, at which a shear strength of cohesive soils is zero and then cohesive soils will start to flow, was proposed. Three types of clays (kaolinite, bentonite and kaolinite (50%)+bentonite (50%)) were mixed with three different solutions (distilled water, sea water and microbial solution) at liquid limit state and then their water contents were increased step by step. Then, their undrained shear strength was measured using a portable vane shear device called Torvane. The ranges of undrained shear strength at liquid and plastic limits are 3.6-9.2 kPa and 24-45 kPa, respectively. On the other hand, the water content that corresponds to the value of the undrained shear strength changing most rapidly is called flow water content. The flow limit refers to the water content when undrained shear strength of cohesive soils is zero. In order to investigate the relationship between liquid limit and flow limit, the cohesive index was defined as a value of the difference between flow limit and liquid limit. The new plasticity index was defined as the value of difference between flow limit and plastic limit. The new liquidity index was also defined using flow limit. The values of flow limit are 1.5-2 times higher than those of liquid limit. At the same time, the values of new plasticity index are 2-5.5 times higher than those of original plasticity index.

• Journal of the Korean Geotechnical Society
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• v.23 no.2
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• pp.29-34
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• 2007

This study examines the effects of heat treatment under laboratory conditions for mixtures of two types of clay (kaolinite and montmorillonite). Clay samples were burned with different temperatures ranging from $100^{\circ}C\;to\;500^{\circ}C$. The Atterberg limits such as liquid and plastic limits were influenced with heat treatment. According to the experimental results, the liquid limits slightly decreased between $100^{\circ}C\;to\;300^{\circ}C$, whereas rapid decreases were observed after $300^{\circ}C$. The plastic limits did not show noticeable differences in the interval $100^{\circ}C\;to\;400^{\circ}C$. But the clay samples showed non plastic behavior at $500^{\circ}C$. The amount of NaCl was getting decreased with temperature. It also revealed that the pH values were also influenced with heat treatment, and the cation exchange capacity (C.E.C) values decreased with temperature.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.549-555
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• 2009

Based on three-dimensional(3-D) finite element limit analyses, this paper provides limit and TES (Twice-Plastic Load) loads for mitred pipe bends under bending and pressure. The plastic limit loads are determined from FE limit analyses based on elastic-perfectly-plastic materials using the small and large geometry change option. A wide range of parameters related to the mitred bend geometry is considered. Based on the finite element results, closed-form approximations of plastic limit and TES plastic load solutions for mitred pipe bends under bending are proposed.

• The Journal of Engineering Geology
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• v.14 no.2
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• pp.199-210
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• 2004

In this study, the physical and mechanical properties of the weathered shale soils distributed in the Hwasun area have been measured in the laboratory. The physical and mechanical properties of the weathered shale soils in the study area as follows: the specific gravity is 2.66 to 2.68, the liquid limit is 36.39 to 36.92(%), the plastic limit is 18.53 to 19.48(%), the plasticity index is 17.44 to 17.86 and soil classification is CL. The maximum dry unit weight and optimum moisture content as calculated by compaction test is 22.5 to 23% and 1.58 to $1.61t/\textrm{m}^3$, respectively. The result of direct shear testing show that cohesion in saturated and unsaturated conditions increases according to the increase of dry unit weight. Internal friction angle in an unsaturated condition increases with an increase of dry unit weight, but in a saturated condition, it increases after decreasing. When compares with engineering characteristics of tile weathered shale soils in the Daegu area (Kim et al., 1995), specific gravity is found to be similar, but the liquid and plastic limit of soil samples in this study area is slightly higher than those of soil samples in the Daegu area.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.147-158
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• 2011

The purpose of this research was to analyze the connections of the seismic-performance values for domestic-performance-based designs. Basic research on the performance design method has been increasing of late, along with performance-based organization investigations. These investigations concern the performance level state of steel structure buildings. According to the performance limit state, seismic-performance values should be presented as appropriate steel structure engineering amounts. The first step, based on the full-scale steel structure experiments, involves researching on the making of a basic document. The moment-rotation angle relationship results of the experiment on the moment-frame connection were used to assort the functional and undamaged limits, which were assumed to be less than the yield moment. Moreover, the repairable and safety limits, which were assumed to exist between the yield and maximum moments, were assorted by investigating the accumulated plastic deformation ratio.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.825-832
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• 2010

Although a critical section reaches its flexural strength in reinforced concrete structures, the structure does not always fail because moment redistribution occurs during the formation of plastic hinges. Inelastic deformation in a plastic hinge region results in plastic rotation. A plastic hinge mainly depends on material characteristics. In this study, a plastic hinge length and plastic rotation are evaluated using the flexural curvature distribution which is derived from the material models given in Eurocode 2. The influence on plastic capacity the limit values of the material model used, that is, ultimate strain of concrete and steel and hardening ratio of steel(k), are investigated. As results, it is appeared that a large ultimate strain of concrete and steel is resulting in large plastic capactiy and also as a hardening ratio of steel increases, the plastic rotation increases significantly. Therefore, a careful attention would be paid to determine the limit values of material characteristics in the RC structures.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.222-225
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• 1997

This paper describes experimental investigation on the forming limit for mash-seam welded sheets. The uniaxial tensile test was conducted to evaluate the mechanical properties of weld bead. Experimental forming limit diagrams were investigated for the different thicknesses and properties of welded sheets.