• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.31-41
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• 2013

The dredged soils of western sea of Korea have been used as the fill materials because it possess the characteristics that constitute silt, silty sand and sand mainly. However, a study on dredged soils as the fill materials is insufficient. Hence, in this present study, the application the dredged soils of western sea of Korea as the fill materials was confirmed. Primary, the composition characteristics of the ground was analyzed to confirm the application on dredged soils as the fill materials by the piezo-cone penetration test. In laboratory test, it was performed the self-weight consolidation test for mechanical characteristics of the dredged soils. The direct shear test using self-weight consolidation test sample for shear strength characteristics was performed after self-weight consolidation test. Additionally, the mechanical characteristics of the dredged soils on elapsed time using self-weight consolidation test sample, which is drained naturally, was evaluated. The dredged soils of western sea of Korea show that unit weight and shear strength is increased as natural drain time elapses.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1113-1117
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• 2009

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.123-133
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• 2001

Since most of soil slopes are in an unsaturated state, it is necessary to consider the unsaturated characteristics of soil slopes, in order to obtain more reasonable results. Therefore in this study we supplemented a slope stability analysis program to consider them, based on the concept of limit equilibrium. We also applied an optimization technique to search for a failure surface. Besides, we carried out experiments to obtain the unsaturated soil properties required in the analysis with weathered granite soils. We formulated a nonlinear apparent cohesion relationship with the matrix suction to be able to apply the unsaturated shear strength characteristics to the stability analysis. In addition, we intended to obtain more accurate soil water characteristic curves(SWCC) by measuring the change in volume of the specimen in the SWCC tests. As a result, we could appropriately assess the change of the safety factor according to the rainfall intensity and duration, by considering the variation of suction, permeability, and shear strength caused by the infiltration of rainfall into slopes.

• Journal of the Korean GEO-environmental Society
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• v.13 no.8
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• pp.65-73
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• 2012

Soil-rock interface, mainly founded in Granite region of Korea, is known as one of the important factor of the slope failure at the rainfall due to smaller shear strength than soil itself. However, research of the effect on slope stability by soil-rock interfaces is insufficient. Therefore, a series of direct shear tests were performed in order to investigate the effect of soil-rock interface on slope stability. The method of tests is to get sand itself and sand-artificial rock interface shear strength from different grain size of sands and artificial rock samples. The results of tests show that the friction angle of interface depends primarily on particle size and surface roughness. Interface friction angle ratio ${\mu}(={\delta}/{\Phi})$ is in the range of 0.75 ~ 0.96, this results indicate that interface friction angle is smaller than sand itself.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.394-399
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• 2019

Plywood is a laminated wood material where alternating layers are perpendicular to each other. It is used in a liquefied natural gas (LNG) carrier for an insulation system because it has excellent durability, a light weight, and high stiffness. An LNG cargo containment system (LNG CCS) is subjected to loads from gravity, sloshing impact, hydrostatic pressure, and thermal expansion. Shear forces are applied to an LNG CCS locally by these loads. For these reasons, the materials in an LNG CCS must have good mechanical performance. This study evaluated the shear behavior of plywood. This evaluation was conducted from room temperature ($25^{\circ}C$) to cryogenic temperature ($-163^{\circ}C$), which is the actual operating environment of an LNG storage tank. Based on the plywood used in an LNG storage tank, a shear test was conducted on specimens with thicknesses of 9 mm and 12 mm. Analyses were performed on how the temperature and thickness of the plywood affected the shear strength. Regardless of the thickness, the strength increased as the temperature decreased. The 9 mm thick plywood had greater strength than the 12 mm thick specimen, and this tendency became clearer as the temperature decreased.

• Structural Engineering and Mechanics
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• v.45 no.2
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• pp.233-257
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• 2013

Given the yield shear of a single-story inelastic structure with simple eccentricity, the problem of strength distribution among the resisting elements is investigated, with respect to minimize its torsional response during a ground motion. Making the hypothesis that the peak accelerations, of both modes of vibration, are determined from the inelastic acceleration spectrum, and assuming further that a peak response quantity is obtained by an appropriate combination rule (square root of sum of squares-SRSS or complete quadratic combination-CQC), the first aim of this study is to present an interaction relationship between the yield shear and the maximum torque that may be developed in such systems. It is shown that this torque may be developed, with equal probability, in both directions (clockwise and anticlockwise), but as it is not concurrent with the yield shear, a rational design should be based on a combination of the yield shear with a fraction of the peak torque. The second aim is to examine the response of such model structures under characteristic ground motions. These models provide a rather small peak rotation and code provisions that are based on such principles (NBCC-1995, UBC-1994, EAK-2000, NZS-1992) are superiors to EC8 (1993) and to systems with a stiffness proportional strength distribution.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.759-766
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• 2004

The addition of steel fiber with concrete significantly improves the engineering properties of structural members, notably shear strength. The purpose of this study is to determine the steel fiber shape, aspect ratio and volume fraction ratio in a point of practical usage as structural members. Steel fiber factor and volume fraction are also considered to verify the strengthening effect in member level. From the reviewing of previous researches and analyzing of consecutive material test results, the optimum shape and length of steel fiber, which can have a good strengthening effects were defined as a hooked end type and larger than 1.5 times of maximum gravel size. Analyzing the test results of strength and deformation capacity, aspect ratio 75 and volume fraction $1.5\%$ can be having a maximum strengthening effect of steel fiber. Also steel fiber factor, tensile splitting strength, and flexural strength are found as key parameter in shear strengthening effect in member level.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.85-94
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• 2013

PURPOSES: The performance of tack coat, commonly used for layer interface bonding, is affected by application rate and curing time. In this study, bonding strength tests were performed according to the application rate and curing time of asphalt emulsion. Based on finding from this study, optimum application rates and curing times are proposed. METHODS: In order to investigate bonding characteristic of asphalt emulsion, tests were performed on both asphalt concrete pavement and portland concrete pavement. Also, asphalt emulsions were tested at the application rate of 0, 0.2, 0.4, 0.6, and $0.8{\ell}/m^2$ and at the curing time of 0, 0.5, 1, 2, and 24 hours. Pull-off test and shear bonding strength test, which commonly used for bonding strength measurement of asphalt emulsion, were adopted for this study. To assess field performance under different testing condition, asphalt emulsions were applied to in-service pavement. Throughout coefficient of determination analysis between material index properties from asphalt emulsion and mechanical response from bonding strength tests, performance correlativity was analyzed. RESULTS: Test results show that optimum application rate for asphalt overlay on asphalt concrete pavement (AOA) and asphalt overlay on concrete pavement (AOC) was $0.4{\sim}0.5{\ell}/m^2$ and $0.3{\sim}0.5{\ell}/m^2$, respectively. According to the curing time increment, tensile strength and shear strength of AOC were increased to 22~44% and 20~39%, respectively. AOA case also show strength increment in tensile strength (42%) and shear strength (9%). We tested the applicability of tack coat materials at the field sites, and our findings demonstrated that the bonding (for D and E) and rapid curing (for B, C, and D, E) performances were superior than others. Among material index properties, there was a high correlation between penetration ratio and bonding strength test result. CONCLUSIONS : Result show that interlayer bonding strength was affected by asphalt emulsion type, application rate and curing time. AOC required slightly higher application ($0.1{\ell}/m^2$) than AOA. Both AOA and AOC cases show higher strength at longer curing time. Up to 2hours of curing, rapid strength increments were observed, but strength increment ratio was decreased after 2hours of curing. From the observed correlation between penetration ratio and bonding strength, it is expected that penetration ratio can be used as one of important factors affecting bonding strength analysis.

• Journal of Korean Association for Spatial Structures
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• v.24 no.1
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• pp.37-45
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• 2024

Steel plate shear walls (SPSWs) have been recognized as an effective seismic-force resisting systems due to their excellent strength and stiffness characteristics. The infill steel plate in a SPSW is constrained by a boundary frame consisting of vertical and horizontal structural members. The main purpose of this study was to investigate deformation modes and hysteretic characteristics of steel plate shear walls (SPSWs) to consider the effects of their aspect ratios and width-to-thicness ratios. The finite element model (FEM) was establish in order to simulate cyclic responses of SPSWs which have the two-side clamped boundary condition and made of conventional steel grade. The stress distribution obtained from the FEA results demonstrated that the principal stresses on steel plate with large thickness-to-width ratio were more uniformly distributed along its horizontal cross section due to the formation of multiple struts.

• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.31-39
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• 2006

In this study, modified triaxial compression tests were carried out to investigate the characteristics of shear strength of unsaturated dredged soils. The variation of shear strength generally depends on more matric suction than drained conditions, and then is gradually converged in matric suction 100kPa. It indicates that the effective angle of internal friction and effective cohesion in unsaturated conditions increase due to degree of saturation, namely, matric suction than those of saturated conditions. Therefore, it shows that apparent friction angle, ${\phi}^b$ due to the variation of matric suction to evaluate reasonable shear strength parameters in unsaturated soils should be considered.