• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.476-481
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• 2009

Bi-directional load test is one of O-cell tests. The O-cell test is a system which may be used for performing static load tests on cast in situ reinforced concrete bored piles. The technique was devised and developed by Osterberg of Northwestern University(USA) and has been in use around the world. The principle of the method is that an O-cell is installed in a cast in situ bored pile base. Once the pile concrete reaches its design strength the cell is connected to an hydraulic pump and pressured. Pressurization causes the cell to expand, developing an upward force on the section of pile above the cell loads, pile movements and strains within the pile then enable the capacity of the pile and its load settlement curves to be ascertained. The O-cell pile load test with variable end plate is operated on second steps - the first step is to confirming end bearing capacity with variable end plate and the second step is similar to the conventional O-cell test. In the study, To calculate ultimate capacity of bi-directional load test using model with the pile with variable end plate O-cell.

• Structural Engineering and Mechanics
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• v.59 no.3
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• pp.455-473
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• 2016

Methods for the seismic demands evaluation of structures require iterative procedures. Many studies dealt with the development of different inelastic spectra with the aim to simplify the evaluation of inelastic deformations and performance of structures. Recently, the concept of inelastic spectra has been adopted in the global scheme of the Performance-Based Seismic Design (PBSD) through Capacity-Spectrum Method (CSM). For instance, the Modal Pushover Analysis (MPA) has been proved to provide accurate results for inelastic buildings to a similar degree of accuracy than the Response Spectrum Analysis (RSA) in estimating peak response for elastic buildings. In this paper, a simplified nonlinear procedure for evaluation of the seismic demand of structures is proposed with its applicability to multi-degree-of-freedom (MDOF) systems. The basic concept is to write the equation of motion of (MDOF) system into series of normal modes based on an inelastic modal decomposition in terms of ductility factor. The accuracy of the proposed procedure is verified against the Nonlinear Time History Analysis (NL-THA) results and Uncoupled Modal Response History Analysis (UMRHA) of a 9-story steel building subjected to El-Centro 1940 (N/S) as a first application. The comparison shows that the new theoretical approach is capable to provide accurate peak response with those obtained when using the NL-THA analysis. After that, a simplified nonlinear spectral analysis is proposed and illustrated by examples in order to describe inelastic response spectra and to relate it to the capacity curve (Pushover curve) by a new parameter of control, called normalized yield strength coefficient (${\eta}$). In the second application, the proposed procedure is verified against the NL-THA analysis results of two buildings for 80 selected real ground motions.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.1
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• pp.59-65
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• 2004

Recently, as steel structures become higher and more long-spanned, application of high strength steel. SM570, is considered, For accurate seismic design, seismic analysis of steel structures needs a constitutive equation describing the characteristic of steel materials under non-proportional cyclic loading, While the use of SM570 material is much increased these days, research for description and generalization of cyclic plasticity behavior are insufficient, In this study, a cyclic plasticity model is proposed by results of material tests, i.e, monotonic and low cycle tests, Proposed cyclic plasticity model is applied to 3-Dimensional FE program and we carried out seismic analysis of pipe-section steel pier using SM570, Comparison between experiment and analysis results shows that the proposed constitutive equation is able to describe exactly the complicated plastic behavior of steel structure using SM570.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.467-473
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• 2002

The purpose of this study is to investigate the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load and to provide result for developing improved seismic design criteria. A computer program named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology) for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The strength increase of concrete due to the lateral confining reinforcement has been taken into account to model the confined concrete. In boundary plane at which each member with different thickness is connected local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel. The proposed numerical method for the inelastic behavior and ductility capacity of reinforced concrete frame subjected to cyclic lateral load is verified by comparison with reliable experimental results.

• Journal of Korea Game Society
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• v.16 no.4
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• pp.69-78
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• 2016

With the development of game technology, the realistic game graphics, interface technology, and various content services with immersion are being required in the content area. NUI has been developed through CLI and GUI. Unlike the conventional methods, it is an interface that could be the intuitive and realistic interface for human as a natural action realized. we propose a boxing simulation game using leap motion of it. Providing a realistic 3D experimental environment through VR headsets game, we also propose a method that can be calculated the scores if the user-controlled interface (fist) could be to punch the target (sandbag) of the internal in accordance with changes of the angle of target impact with the physical characteristics.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.193-196
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• 2008

This paper proposes a method to predict the ductility capacity of reinforced concrete beam-column joints failing in shear after the formations of plastic hinges at both ends of the adjacent beams. The current design code divides joints into two categories: Type 1 for structures in non seismically hazard area and Type 2 in seismically hazard area. While there are many researches related to joint shear strength in Type 1, those in regard to joint ductility capacity of Type 2 are scarce. This paper classified the ductility capacity of beam-column joints into column, joint panel, and beam deformability. Since a brittle failure such as shear or bond failure in the columns must be avoided, column deformability was calculated by elastic analysis. The plastic hinges of the adjacent beams affect joint deformability. Therefore, the prediction of joint deformability was calculated with consideration to the degradation of the diagonally compressed concrete due to the strain penetration.

• Journal of the Korean Geotechnical Society
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• v.33 no.6
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• pp.27-36
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• 2017

Gravel compaction pile method has been widely used to improve the soft ground on the land or sea as one of the soft ground improvement technique. The ultimate bearing capacity of the ground reinforced by gravel compaction piles is affected by the soil strength, the replacement ratio of pile, construction conditions, and so on, and various prediction equations have been proposed to predict this. However, the prediction of the ultimate bearing capacity using the existing models has a very large error and variation, and it is not suitable for practical design. In this study, multiple regression analysis was performed using field loading test results to predict the ultimate bearing capacity of ground reinforced by gravel compaction pile, and the most efficient input variables are selected through evaluation of error by leave one out cross validation, and a multiple regression equation for the prediction of ultimate bearing capacity was proposed. In addition, the prediction error was evaluated by applying artificial neural network using the selected input variables, and the results were compared with those of the existing model.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.1
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• pp.57-70
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• 2002

Since early in the 90's, the need for construction of underground rock structures such as long and large section traffic tunnel, energy storage cavern, industrial facility, etc. has been largely increased because the Korean territory is not wide and about 65 % of the land consists of mountainous region. The initial rock stress measurement has been widely conducted to provide the quantitative information on the stress state of engineering site at the design stage of underground rock structures. Among the diverse methods developed for measuring rock stress, hydraulic fracturing test is most popularly used because it is applicable at pre-construction stage and has no limit in testing depth. In this paper, the characteristics of initial rock stress state in mountainous region were studied on the basis of the in-situ hydraulic fracturing stress measurement results from the 60 test boreholes in various parts of Korea.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1171-1176
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• 2005

The latest technical development of steel plate girder railway bridge are developing in ways to maximize its durability of materials in use of high strength steel and efficiency of maintenance and management by the introduction of simplified and standardization ideas. In addition to this, it is also expected to reduce the cost of bridge construction and to simplify the process of bridge manufacturing. Referring to this, composite few plate girder railway bridge is highly recommendable that is very economical with the fine exterior. In this paper, it will analyse the variation of dynamic behavior of existing composite few plate girder railway bridge with ballast caused by modified Slab Track through interpretation of limited enzyme in order to obtain the existing data for improvement of Slab Track system from Ballast Track system. Consequently, it can help maximize economic efficiency and structural capability. As a results, although the natural frequency by modified Slab Track are decreased, it is hardly influencing on the safety of railway bridges. It is also evident in the case of slab deck with a reduced scale in comparison with Ballast Track. Therefore, it is expected to reduce the cost of a railway bridge plan. And, it can expect the synergistic effect of the ensure long term durability of bridge caused by decreased stresses of bottom flange due to reduced dead load. As a result, the analytical study are carried out to investigate the composite few plate girder railway bridge could be the optimal design method for the dynamic safety of a girder section.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.1 s.24
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• pp.9-14
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• 2006

Analysis has been made of the anti-corrosive property of organic coating under the shear stress of the flow by means of AC impedance method. Marine anti-corrosive painted panels were placed in the water channel with varying flow rate, thereby experiencing varying flow shear stress on the surfaces. The velocities of the salt water were ranged from 1.48 to 5.2 m/s and the coating thickness of from $70{\mu}m\;to\;140{\mu}m$. For all coating thicknesses investigated, the poorer anti-corrosive property and the lower adhesion strength have been found for the higher shear stress. It has been found that the shear stress accelerates the aging of organic marine coatings.