• Geomechanics and Engineering
• /
• v.3 no.2
• /
• pp.117-130
• /
• 2011

The methods of design available for geocell-supported embankments are very few. Two of the earlier methods are considered in this paper and a third method is proposed and compared with them. In the first method called slip line method, plastic bearing failure of the soil was assumed and the additional resistance due to geocell layer is calculated using a non-symmetric slip line field in the soft foundation soil. In the second method based on slope stability analysis, general-purpose slope stability program was used to design the geocell mattress of required strength for embankment. In the third method proposed in this paper, geocell reinforcement is designed based on the plane strain finite element analysis of embankments. The geocell layer is modelled as an equivalent composite layer with modified strength and stiffness values. The strength and dimensions of geocell layer is estimated for the required bearing capacity or permissible deformations. These three design methods are compared through a design example. It is observed that the design method based on finite element simulations is most comprehensive because it addresses the issue of permissible deformations and also gives complete stress, deformation and strain behaviour of the embankment under given loading conditions.

• Advances in aircraft and spacecraft science
• /
• v.2 no.3
• /
• pp.345-365
• /
• 2015

This paper focuses on the design, fabrication, testing and analysis of a novel load-bearing element with energy dissipation capability. A single element comprises two von-Mises trusses (VMTs), which are sandwiched between two plates and connected to dashpots that stroke as the VMTs cycle between stable equilibrium states. The elements can be assembled in-plane to form a large plate-like structure or stacked with different properties in each layer for improved load-adaptability. Also introduced in the elements are pre-loaded springs (PLSs) that provide high initial stiffness and allow the element to carry a static load even when the VMTs cannot under harmonic disturbance input. Simulations of the system behavior using the Simscape environment show good overall correlation with test data. Good energy dissipation capability is observed over a frequency range from 0.1 Hz to 2 Hz. The test and simulation results show that a two layer prototype, having one soft VMT layer and one stiff VMT layer, can provide good energy dissipation over a decade of variation in harmonic load amplitude, while retaining the ability to carry static load due to the PLSs. The paper discusses how system design parameter changes affect the static load capability and the hysteresis behavior.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.5
• /
• pp.88-95
• /
• 2015

The thickness of adsorbed molecular layers is the most critical factor in studying thin-film lubrication, and it is the most essential parameter that distinguishes thin-film from thick-film lubrication analysis. The thin film between the shaft and bearing surface within a very narrow gap was considered. The general Reynolds equation has been derived for calculating thin-film lubrication parameters affecting the performance of the circular journal bearing. Investigation of the load-carrying capacity and pressure distribution for the journal bearing considering the adsorbed layer thickness has been carried out. A Reynolds equation appropriate for the journal bearing is used in this paper for the analysis, and it is discussed using the finite difference method of the central difference scheme. The parameters, such as eccentricity and attitude angle, are used for discussing the load-carrying capacity of the journal bearing. The results reported in this paper should be applied to analysis of the journal bearing with different lubrication factors. The steady-state analysis of the journal bearing is conducted using the Reynolds model under thin-film lubrication conditions. For a journal bearing, several parameters, such as a pressure, load capacity, and pressure components of the bearing can be obtained, and these results can be stored in a sequential data file for later analysis. Finally, their distribution can be displayed and analyzed easily by using the MATLAB GUI technique. The load-carrying capability of the journal bearing is observed for the specified operating conditions. This work could be helpful for the understanding and research of the mechanism of thin-film lubrication.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.1
• /
• pp.41-46
• /
• 2008

In this study, the analysis of load transition of PHC pile was performed with the static load test, which was driven in deep soft clay layer of MyungJi site in the western area of Pusan. The results of test showed that the range of unit side resistance of pile in sand layer were $7.4t/m^2$ to $23.3t/m^2$ and $6.4t/m^2$ in the soft clay layer, while the unit base resistance was $955t/m^2$ in dense silty sand layer. To select the most reasonable static bearing capacity formular, the field measured values are compared with the calculated ones from the suggested various formular. In the case of side resistance in sand layer, the suggest formular in the Structural Foundation Design Manual by KGS was most reasonable, while in clay layer Railroad Design Manual.

• Journal of the Korean Geotechnical Society
• /
• v.32 no.7
• /
• pp.35-45
• /
• 2016

Estimation of vertical bearing capacity is critical in the design of bucket foundation used to support offshore structure. Empirical formula and closed form solutions for bucket foundations in uniform sand or clay profiles have been extensively studied. However, the vertical bearing capacity of bucket foundations in alternating layers of sand overlying clay is not well defined. We performed a series of two-dimensional axisymmetric finite element analyses on bucket foundations in sand overlying clay soil, using elasto-plastic soil model. The load transfer mechanism is investigated for various conditions. Performing the parametric study for the friction angles, undrained shear strengths, thickness of sand layer, and aspect ratios of foundation, we present the predictive charts for determining the vertical bearing capacities of bucket foundations in sand overlying clay layer. In addition, after comparing with the finite element analysis results, it is found that linear interpolation between the design charts give acceptable values in these ranges of parameters.

• Journal of the Korean Geosynthetics Society
• /
• v.13 no.1
• /
• pp.53-61
• /
• 2014

Sea gives us a lot of benefits and one of them is a role of transporting goods easily by ship. Accordingly the industrial area or the container yard is constructed either on the low sea or near the sea. Sea dredging ground is made by pumping them using dredge pump to the inside of embankment after dredging undersea soils. The dredging ground after pumping is in the slurry state but as time goes, consolidation by the own weight happens and evaporation happens at the surface of dredging ground. The evaporation causes the crest layer in the upper side of dredging ground. Under the crest layer there is still a soil of slurry state which has just little bearing resistance. This kind of characteristics makes it difficult to get a exact bearing capacity using the equations proposed until now. In this study we have performed simultaneously both the field loading tests and the cone penetration tests on the sea dredging ground. From the result of field tests, new experimental equation for the ultimate bearing capacity has been proposed. If we use the new equation, it is believed that some design of sea dredging ground could be more accurate.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1993.12a
• /
• pp.77-84
• /
• 1993

Systems with journal bearings generally operate in large scale and under severe loading conditions such as steam generator turbines and internal combustion engines, in contrast to the machineries using rolling element bearings. Failure of the bearings in these machineries can result in the system breakdown. To avoid the time consuming repair and considerable economic loss, the detection of incipient failure in journal bearings becomes very important. In this experimental approach, acoustic emission monitoring is employed to the detection of incipient failure caused by intervention of foreign particles most probable in the journal bearing systems. It has been known that the intervention of foreign materials, insufficient lubrication and misassembly etc. are principal factors to cause bearing failure and distress. The experiment was conducted under such designed conditions as inserting alumina particles to the lubrication layer in the simulated journal bearing system. The results showed that acoustic emission could be an effective tool to detect the incipient failure in journal bearings.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.6
• /
• pp.63-69
• /
• 2006

In this paper, a method is presented for estimating the bearing capacity of shallow foundations based on the Discrete Element Method (DEM). By applying Winkler-springs for accounting for the compatibility between soil blocks, the proposed method can estimate the state of stress at failure surface and the ultimate bearing capacity. For the investigation of the application of the method, example problems about shallow foundations on the single layer and two layers soil are analyzed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2004.03b
• /
• pp.544-551
• /
• 2004

Piles are structural elements made of steel, concrete or timber, and utilize as pile foundation which is one of deep foundations. Driven pile among them, which drives pile into the ground, is fast-constructable, less expensive and it supplies much bearing capacity. For these reasons, its demand is steady. In this study, by selecting the cases which reached ultimate failure during in-situ static loading tests, bearing capacities acquired from these tests were compared with those computed by existing theories and formula. As the results of the analysis, ultimate bearing capacity computed by theoretic formula were less or similar to those of test results in most cases, but lower ground water level and more dense layer where end of piles were reached remarkably high bearing capacity in theoretical methods. ${\beta}-method$ and Korean structure foundation design standard were sensitive to ground physical properties. Meyerhof metbod and API code were relatively independent from site condition.

• Structural Engineering and Mechanics
• /
• v.62 no.1
• /
• pp.79-84
• /
• 2017

Utilizing composite members in structures has been considered by many researchers in the past few decades. Using FRP can be very effective owing to its excessively high-tensile strength, which compensate concrete weak performance in tension. In this research, the studied composite beam includes a GFRP semi-confined trapezoidal section covered by GFRP and concrete layers. To assess the bearing capacity, a finite-element model of a composite beam subjected to displacement control loading has been developed and the results were validated using experimental results found throughout the literature. Several parameters affecting the bending performance and behavior of the semi-confined beam have been investigated in this study. Some of these parameters included the thickness of GFRP trapezoidal section members, concrete layer thickness, GFRP layer thickness and the confinement degree of the beam. The results revealed that the beam confinement had the highest effect on the bearing capacity due to prevention of separation of concrete from GFRP which causes the failure of the beam. From the results obtained, an optimal model of primary beam section has been introduced, which provides a higher bearing capacity with the same volume of materials used in the original beam section.