• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.512-519
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• 2002

본 연구에서는 임의의 형상의 다중세포 단면을 갖는 복합재료 블레이드에 대한 유한요소 구조해석을 수행하였다. 보 해석 모델은 구조연성 효과와 단면 벽의 두께, 횡 전단변형, 비틀림과 연관된 워핑 및 워핑구속효과 등을 고려하고 있다. 블레이드 힘-변위 관계식은 Reissner의 반복족에너지 함수를 이용한 혼합이론을 적용하여 유도하였다. 이 관계식은 굽힘 및 전단에 대해서는 Timoshenko 보의 형태로 그리고 비틀림 변형은 Vlasov 이론으로 근사하고 있다. 결과적인 [7×7] 구조강성 행렬은 전단변형 및 전단강성계수들을 특이한 가정에 의존하지 않고도 해석적으로 기술하고 있다. 본 정식화 과정을 통해서 구한 보 이론을 이중세포로 구성된 에어포일 형상의 복합재료 블레이드에 적용하였으며, 기존의 실험 연구 및 다차원 유한요소해석 결과들과 비교 연구를 수행하여 본 해석모델의 타당성을 보이고자 하였다.

• Journal of the Korean Geosynthetics Society
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• v.5 no.3
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• pp.9-15
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• 2006

The Green Wall system is one of segmental concrete crib type earth retaining wall. Green wall is constructed as procedures that lay the front stretchers, rear stretchers and headers then making a rigid body through harden filled soil of interior cell. Recently, Green Wall method is applied in variable cutting ground construction because of advantage which minimize to cut base ground. In case of Green Wall method is constructed with soil nail method, expect that total system stability will increase more than flexible facing because of facing stiffness is big. However, in this case of design, facing stiffness is not considered so that is poor economy. Hence, in this study, stability increasing effect of total system analyze about that soil nail method is constructed with rigidity facing like a Green Wall method. In present study, laboratory model tests was performed for analysis on stability increasing effect of total system about changing stiffness of facing. LEM analysis conducted for evaluation on safety factor of total system sliding that facing condition changed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.563-569
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• 2016

This paper presents the resizing method of columns and beams that considers column-to-beam strength ratios to simultaneously control the initial stiffness and ductility of steel moment frames. The proposed method minimizes the top-floor displacement of a structure while satisfying the constraint conditions with respect to the total structural weight and column-to-beam strength ratios. The design variable considered in this method is the sectional area of structural members, and the sequential quadratic programming(SQP) technique is used to obtain optimal results from the problem formulation. The unit load method is applied to determine the displacement participation factor of each member for the top floor lateral displacement; based on this, the sectional area of each member undergoes a resizing process to minimize the top-floor lateral displacement. Resizing members by using the displacement participation factor of each member leads to increasing the initial stiffness of the structure. Additionally, the proposed method enables the ductility control of a structure by adjusting the column-to-beam strength ratio. The applicability of the proposed optimal drift design method is validated by applying it to the steel moment frame example. As a result, it is confirmed that the initial stiffness and ductility could be controlled by the proposed method without the repetitive structural analysis and the increment of structural weights.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.12
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• pp.994-1000
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• 2002

In periodically repeated cyclic structures, small property irregularity of their substructures often causes significant difference in their dynamic responses. which results in unpredicted premature failures. The small irregularity and the resulting phenomenon are called the mistuning and the vibration localization. respectively. In this paper, the vibration localization phenomena due to mistuned coupling effects are investigated. To effectively achieve the objective, a simple coupled multi-pendulum system Is employed. The results show that if there exists some coupling stiffness irregularity, vibration localization may occur and becomes more predominant as the number of substructures increases.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.181-190
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• 2004

A new inelastic design method performing iterative calculations using secant stiffness was developed. Since the proposed design method uses linear analysis, it is convenient and stable in numerical analysis. At the same time, the proposed design method can accurately estimate the inelastic strength and ductility demands of the members by performing iterative calculation. In the present study, the procedure of the proposed design method was established. Design examples using the proposed method were presented, and its advantages were highlighted by comparisons with existing design methods using elastic or plastic analysis. Unlike the existing inelastic design methods performing the preliminary design on the structure and checking its validity using nonlinear analysis, the proposed integrated analysis-design method can directly calculate the strength and ductility demands of each member. In addition, the proposed design method can address the inelastic design strategy intended by the engineer, such as strength and ductility limits of members and the design concept of strong-column and weak-beam. As a result, economical and safe design can be achieved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.113-121
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• 2015

Building using masonry accounts for most of the smaller houses in Korea but due to brittle behavior and low ductility the frequency of usage has decreased in recent years. Despite this, this form of building has been gaining attention overseas for its low cost in construction and environment-friendliness of the materials. As such, many studies are being conducted to resolve the disadvantages in structure. This study produced an specimen for masonry-filled wall and the intersection to confirm the difference in structural movement depends on the existence or lack of expansion joint and verified the reinforcement effect from inserting a connecting steel item (steel plate, stainless steel twist bar). The experiment results show that the specimen with a steel plate inserted saw an increase in durability and an improvement in the strength of the specimens, while the specimen that had stainless steel twists bar inserted saw an increase in ductility that did not cause brittle failure, indicating that the reinforcement effects of inserting a connecting steel item are effective.

• 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.

• Composites Research
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• v.14 no.6
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• pp.9-15
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• 2001

In the present work, a linear static analysis is presented for thin-walled prismatic box-beams made of generally anisotropic materials. A mixed beam theory has been used to model and carry out the analysis. Several different constitutive assumptions for the shell-wall of the beam section are assessed into the beam formulation. Simple layup cases of box-beams representing bending-torsion or extension-torsion coupled configuration have been considered and tested to clearly show the effects of elastic couplings of the beam. A detailed finite element structural analysis using the MSC/NASTRAN has been carried out to validate the current analytical results. Numerical results show that appropriate assumptions for the constitutive relations are important and crucial for the accurate prediction of beam stiffness constants and also thor the beam behavior.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.243-244
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• 2010

Reinforced concrete beam are very diverse materials that are used to bending reinforcement. Recently the case of FRP flexural reinforcement is actively being used is an excellent weight - rigidity. However, use of FRP bending reinforcement in brittleness material properties of concrete in an actual field application causes destruction of detachment and attachment is being considered as a major cause of destruction. For hybrid laminating plates, tensile and three-point bending tests were performed considering various designs and fabricating methods for hybrid FRP plates. Tensile property of each test specimen was investigated and the research parameter of hybrid laminating plates considered here is the combining ratio of fiber to aluminum contents.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.4
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• pp.37-48
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• 2010

The seismic control effect of reinforced concrete structures with low energy dissipating capacity due to stiffness degradation is investigated through nonlinear time history analysis. The primary structure is idealized as a SDOF system of modified Takeda hysteresis rule and an elasto-perfectly-plastic nonlinear spring is added to represent a hysteretic damping device. Based on statistics of the numerical analysis, equivalent linearization techniques are evaluated, and empirical equations for response prediction are proposed. As a result, estimation of the ductility demand with proposed empirical equations is more desirable than the equivalent linearization techniques. The optimal yield strengths based on empirical equations are significantly different from the optimal yield strength of elasto-perfectly-plastic systems. Also, the results indicate that the reduction effect of the ductility demand is more remarkable for smaller natural periods.