• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.390-397
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• 2014

BO-105 helicopter applies hingeless rotor hub system and blade root uses a flexure of hingeless rotor hub system. So bending stiffness reinforcement for flexure was conducted for preparation of whirl tower test using BO-105 blade. Bending moment of flexure area was calculated with FE modeling of section shape for stiffness reinforcement of flexure and thickness of composite material for reinforcement was chosen. Flexure bending stiffness reinforcement was conducted and bending stiffness measurement test was performed before and after bending stiffness reinforcement. And the test data are compared with analysis results.

• Journal of Korean Society of Steel Construction
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• v.16 no.2 s.69
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• pp.191-200
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• 2004

In this paper, the modified method of orthotropic rigidities for stiffened plates with open ribs is proposed to solve the problem of the inaccurate results of the orthotropic plate analysis according to the dimensions of stiffened plates. In analyzing various types of stiffened plates with open ribs using the isotropic and orthotropic plate element, orthotropic plates are found to gave smaller maximum displacements compared to isotropic plates in a range that is smaller than the special rigidity ratio and reversely. Therefore, obtaining a more accurate solution of the orthotropic plate analysis requires modifying the orthotropic rigidities of stiffened plates according to the rigidity ratio. This study presents two modified methods using the displacement function and the displacement ratio. The application of the two methods improves the accuracy of the results of the orthotropic plate analysis, although the modified method using the displacement ratio is better than the method using the displacement function in terms of serviceability and safety. The comparison with the experimental example shows that the proposed modified method improves accuracy. Therefore, the orthotropic plate analysis of stiffened plates with open ribs can achieve more accurate results using the proposed method in this study.

• Magazine of the Korea Concrete Institute
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• v.3 no.1
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• pp.79-85
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• 1991

This paper aims at experimentally investigating the relationship between tensile load and average strain in the tension zone of SFRC beam. Also, it is attempted to find post cracking tension behavior of SFRC under tensile loading condition. The tension stiffening test is conducted on the long prizm of SFRC which embeds reinforcing bar in both ends of member. From this study, an empirical equation which represents the tension stiffening effect(i.e.effect of increasing tensile-~3trengthening contnbuted by SFRC when the reinforcing bar embeded in the SFRC member is under tensile loading condition) as a function of the average strain is presented .

• Composites Research
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• v.17 no.2
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• pp.9-14
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• 2004

In this study, analytical investigations on the flexural behavior of FRP reinforced concrete slab were discussed. In the derivation of analytic solution, the FRP reinforced concrete slab was modeled as a structural orthotropic plate. To determine the flexural rigidities of an orthotropic plate model, the elastic equivalence method was employed. In the finite element analysis, the approximate method to determine the rigidity matrix of orthotropic plate element was also suggested using the elastic equivalence method. The results obtained by the analytical solution and the finite element analysis were compared with that of experiment.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.600-602
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• 2012

폐단면리브 적용 판의 면내 압축좌굴 거동 특성 중에서 보강재 강성이 작고 비교적 낮은 임계하중을 받는 경우 전체기둥좌굴 거동이 예상된다. 본 논문은 폐단면리브 단면 강성의 고려 방안에 따라 단순 보 유사모형을 정립하고 전체좌굴에 대해 에너지 근사해법을 적용하여 전체좌굴강도 근사해를 유도하기 위한 기초적인 연구방안으로써 검토한 내용을 소개하고자 한다. 유사모형의 폐단면리브 중심에서 휨강성이 발휘되는 것으로 가정하여 모형화 하였다. 폐단면리브 보강판의 프로토타입 모델에 대해 직교이방성 $[(0^{\circ})_4]_s$와 Cross-ply $[(0^{\circ}/90^{\circ})_2]_s$ 적층단면을 각각 고려한 유한요소 해석을 실시하였다. U리브 단면강성에 따른 복합적층 보강판의 탄성좌굴강도 해석결과를 근사해 공식과 비교하고 U리브로 보강된 복합적층판의 좌굴모드 변화양상을 수치해석적으로 검토하였다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.66 no.1
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• pp.35-41
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• 2024

측면구속은 지오그리드에서 골재 입자의 상호결합과 관련된 주요 보강 메커니즘으로 알려져 있다. 본 연구에서는 실내실험을 통해 얻은 지오그리드-골재 상호결합에 의한 국부적 강성증가에 대한 결과를 토대로, 지오그리드로 보강된 기층을 포함한 포장구조체의 탄성 반응 특성을 파악하고자 하였다. 기존의 실험적 연구에서는 지오그리드 배치된 시편 중간 높이로부터 거리가 멀어질수록 전단파 측정에서 추정된 전단탄성계수가 감소한다는 것을 보여주었다. 또한, 삼각형 지오그리드 근처의 강성 증가가 사각형 지오그리드 근처보다 크게 나타났다. 이러한 전단탄성계수 주상도를 기반으로, 수치해석적 연구에서는 기층의 4 개 하부층에 대한 탄성계수 값을 다르게 할당되었다. 층상 탄성해석 프로그램을 사용한 수치해석적 연구는 아스팔트층 하단에서 두 지오그리드 보강 포장시나리오의 수평방향 인장 응력과 변형이 미보강된 시나리오에 비해 감소했음을 보여주었다. 기층 중간깊이에서는 지오그리드 보강 포장시나리오의 압축응력이 미보강된 시나리오에 비해 보다 크게 나타났으며, 지오그리드 보강구간의 인장변형은 미보강된 구간보다 작게 나타났다. 삼각형 및 사각형 지오그리드의 사용은 기층 중간깊이에서 미보강된 시나리오에 비해 수직압축응력을 증가시키고 수직압축변형을 감소시켰다. 노상 상단에서는 지오그리드 보강 포장 구간의 수직 응력과 변형이 미보강된 구간보다 작았는데, 이는 노상의 침하 가능성이 낮다는 것을 보여주었다. 따라서, 지오그리드와 골재 간 미세역학적 상호결합을 기반으로 한 거시적 모델링 방법은 지오그리드로 보강된 아스팔트포장시스템의 역학적 분석에 효과적으로 사용될 수 있을 것으로 기대된다.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.23-32
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• 2005

In this paper, the modified coefficient of the orthotropic rigidity for stiffened plates with open ribs is proposed to improve the inaccurate results of the orthotropic plate analysis. For stiffened plates with rectangular and angle ribs having various aspect ratios and boundary conditions, the aspect ratio and the rigidity ratio are selected as parameters and the parametric study on the modified coefficient is performed. Analyzed results of stiffened plates modeling with the isotropic and orthotropic plate element show that the modified coefficient can be expressed as a function of the rigidity ratio for each rib space regardless of the aspect ratio in case of the aspect ratio under 1 and can be represented as a single union function without regard to rib spaces and aspect ratios in the other case. The results also shows that the effects of the boundary condition on the modified coefficient is small and coefficient functions have different values according to rib shapes. The application to examples shows that the modified coefficient of the orthotropic rigidity improves accuracy. Therefore, the orthotropic plate analysis of stiffened plates with open ribs can easily achieve more accurate results using the coefficient function proposed in this study

• Journal of the Korean Geotechnical Society
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• v.35 no.1
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• pp.17-30
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• 2019

This study presents the application of the numerical and analytical technique to simulate the Load Distribution Ratio (LDR) and to define axial stiffness on reinforcing pile foundation ($K_{vr}$) in vertical extension remodeling structure. The main objective of this study was to investigate the LDR between existing piles and reinforcing piles. Therefore, to analyze the LDR, 3D FEM analysis was performed as variable for elastic modulus, pile end-bearing condition, raft contacts, and relative position of reinforcing pile in a group. Also, using the axial stiffness ($K_{ve}$) of existing piles, the axial stiffness of reinforcing pile was defined by 3D approximate computer-based method, YSPR (Yonsei Piled Raft). In addition $K_{vr}$ was defined by reducing the $K_{ve}$considering the degradation of the existing piles.

• Land and Housing Review
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• v.1 no.1
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• pp.43-50
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• 2010

In this study, the influences of steel dampers on the behavior of RC frames were investigated using the experimental approach to suggest the installation methods of steel dampers using K-barces. The performances of RC frames with dampers can be evaluated by superposition the load-displacement curves of RC frames and steel dampers with regard to the influences of K-braces. Three specimens are tested to investigate the cyclic behavior of RC frames with dampers. The performances of RC frames with dampers with respect to strength, rigidity, and hysteretic performance are examined. It was found that test results demonstrates the effect of seismic retrofit on RC frames with steel dampers(D-RCF-KBSF, D-RCF-KBSP) compared with RC frames(N-RCF). An approximate design curves may not be good agreement with those of the tests, it is conservative enough so that you can design of RC frames with steel damper with regard to the influences of K-braces.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.1
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• pp.1-6
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• 2002

In order to study the characteristics of fiber reinforced bearing, the steel plates of laminated rubber bearing were replaced with fibers which have same effects of steel plates. The comparison of vertical test and horizontal test of laminated rubber bearing and fiber reinforced bearing shows that the effective damping of fiber reinforced bearing is higher than laminated rubber bearing. This result implies the high energy dissipation ability of fiber reinforced bearing under earthquake excitation. These fiber reinforced bearing can be applied to the low-coast building.