• Structural Engineering and Mechanics
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• 제13권3호
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• pp.241-260
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• 2002

The effect of shear coupled with axial force variation on the inelastic seismic behaviour of reinforced concrete bridge piers is investigated in this paper. For this purpose, a hysteretic axial-shear interaction model was developed and implemented in a nonlinear finite element analysis program. Thus, flexure-shear-axial interaction is simulated under variable amplitude reversed actions. Comparative studies for shear-dominated reinforced concrete columns indicated that a conventional FE model based on flexure-axial interaction only gave wholly inadequate results and was therefore incapable of predicting the behaviour of such members. Analysis of a reinforced concrete bridge damaged during the Northridge (California 1994) earthquake demonstrated the importance of shear modelling. The contribution of shear deformation to total displacement was considerable, leading to increased ductility demand. Moreover, the effect of shear with axial force variation can significantly affect strength, stiffness and energy dissipation capacity of reinforced concrete members. It is concluded that flexure-shear-axial interaction should be taken into account in assessing the behaviour of reinforced concrete bridge columns, especially in the presence of high vertical ground motion.

• 한국강구조학회 논문집
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• 제21권4호
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• pp.403-411
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• 2009

본 연구에서는 1995년 고베 지진에 의해 손상을 입은 강 거더 교량에 대해 비선형 지진해석을 수행하였다. 해석수행을 위해 휨-축력 및 휨-전단-축력간의 상호작용을 모사할 수 있는 이력모델을 제안하였다. 제안된 이력모델은 힌지모델 형태로 구조해석 프로그램에 조인트 요소로 연결한 후, 힌지모델 사용한 간편한 해석기법을 교량 교각에 적용하였다. 휨-축력 상호작용을 고려한 해석결과는 상세한 화이버 요소 해석결과와 비교하였고, 좋은 상관관계를 나타내었다. 또한, 휨-축력-전단 상호작용을 고려한 해석결과는 지진하중을 받는 교각의 변위 요소별 검토가 가능하여 교각의 전체 변위성능 분석에 유용하게 사용할 수 있을 것으로 판단된다.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.71-84
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• 2001

The objective of this paper is to develop a simplified method that could predict the strength of concrete filled steel tube (CFT) columns applicable to high strength material under combined axial compression and flexure. The simplified method for determining the strength of CFT columns is based on the interaction curve of the section approached by a polygonal connection of the points. These points are determined by using symmetrical properties of the CFT section. For each point, a simple equation is proposed to determine the strength of the slender columns under compression and flexure. The simple equation was adjusted with results of elasto-plastic analysis results. Validation of the simplified method is undertaken by comparison with data from the test conducted at Kyushu University. These results confirm the fact that the simplified method could accurately and reliably predict the strength of CFT columns under combined axial compression and flexure.

• Earthquakes and Structures
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• 제12권4호
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• pp.469-478
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• 2017

This paper summarizes estimated seismic response results from three-dimensional nonlinear inelastic time-history analyses of some steel buckling-restrained braced (BRB) structures taking into account soil-structure interaction (SSI). The response results involve mean values for peak interstorey drift ratios, peak interstorey residual drift ratios and peak floor accelerations. Moreover, mean seismic demands in terms of axial force and rotation in columns, of axial and shear forces and bending moment in BRB beams and of axial displacement in BRBs are also discussed. For comparison purposes, three separate configurations of the BRBs have been considered and the aforementioned seismic response and demands results have been obtained firstly by considering SSI effects and then by neglecting them. It is concluded that SSI, when considered, may lead to larger interstorey and residual interstorey drifts than when not. These drifts did not cause failure of columns and of the BRBs. However, the BRB beam may fail due to flexure.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall
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• pp.178-185
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• 1999

Six of scaled concrete circular columns were experimentally investigated for the contribution of arch action to the column lateral resistance. For this the specimens with the variation of tranverse hoop steel spacing were tested in absence of axial loading All specimens showed the flexure governing behavior pattern irrelevant to transverse hoop spacing. This indicates that the role of arch action should be understood as the intermediate mechanism causing the interaction between shear and flexural mechanisms A simple truss model was proposed to qualitatively explain this notation but further study is needed to advance its application to general columns.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.21-24
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• 2001

Due to many advantage of advanced composite materials, researches on the composite marine pile is initiated. In this paper, structural characteristics of concrete filled glass fiber reinforced plastic (GFRP) composite pile model are studied. Through 4-point flexural test with various level of axial force, the performance of composite pile model was analyzed. Also numerical method to find P-M interaction diagram of composite pile was developed. It is showed that result of numerical method agrees well with experimental results, thus it is anticipated that numerical procedure can be utilized for design purpose.

• Steel and Composite Structures
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• 제17권3호
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• pp.287-303
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• 2014

8 steel reinforced concrete (SRC) columns with the encased steel ratio of 13.12% and 15.04% respectively were tested under the test axial load ratio of 0.33-0.80 and the low-frequency cyclic lateral loading. The cross sectional area of composite columns was $500mm{\times}500mm$. The mechanical properties, failure modes and deformabilities were studied. All the specimens produced flexure failure subject to combined axial force, bending moment and shear. Force-displacement hysteretic curves, strain curves of encased steels and rebars were obtained. The interaction behavior of encased steel and concrete were verified. The hysteretic curves of columns were plump in shapes. Hysteresis loops were almost coincident under the same levels of lateral loading, and bearing capacities did not change much, which indicated that the columns had good energy-dissipation performance and seismic capacity. Based on the equilibrium equation, the suggested practical calculation method could accurately predict the flexural strength of SRC columns with cross-shaped section encased steel. The obtained M-N curves of SRC columns can be used as references for further studies.

• Earthquakes and Structures
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• 제11권1호
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• pp.141-163
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• 2016

Fiber models have been developed and applied to various structural elements such as shear walls, beams and columns. Only scarcely have fiber models been applied to circular foundation systems such as cast in drilled holes shafts (CIDH). In pile foundations with constraint head boundary conditions, shear deformations can easily contribute to the lateral pile response. However, soil structure interaction formulations such as the p-y method, commonly used for lateral pile design, do not include structural shear deformations in its traditional derivation method. A fiber model that couples shear and axial-bending behavior, originally developed for wall elements was modified and validated on circular cross sections (columns) before being applied to a 0.61 m diameter reinforced concrete (RC) pile with fixed head boundary conditions. The analytical response was compared to measured test results of a fixed head test pile to investigate the possible impact of pile shear deformations on the displacement, shear, and moment profiles of the pile. Results showed that shear displacements and forces are not negligible and suggest that nonlinear shear deformations for RC piles should be considered for fixed-head or similar conditions. Appropriate sensor layout is recommended to capture shear deformation when deriving p-y curves from field measurements.

• 콘크리트학회논문집
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• 제29권2호
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• pp.189-200
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• 2017

C형 및 H형 단면의 구조벽체는 고층 건물에서 횡력저항시스템으로 널리 이용된다. 이러한 이형벽체는 축력과 함께 x축 및 y축에 대한 2방향 휨모멘트를 동시에 받으므로, 안전한 벽체설계를 위해서는 휨-압축 상호작용을 정확히 고려해야 한다. 이 연구에서는, 대칭단면을 갖는 기둥을 위하여 개발된 기존 등하중법을 수정하여, 2방향으로 재하된 C형 및 H형 벽체를 위한 근사설계방법을 제안하였다. 다양한 단면형상을 갖는 이형벽체에 대하여 2방향 모멘트강도를 계산할 수 있는 단면해석 프로그램을 개발하고, 실험결과와 비교를 통하여 프로그램의 정확성을 검증하였다. 또한 개발한 프로그램을 사용한 변수연구를 통하여, C형 및 H형 이형벽체 단면에 대한 2축 상호작용 특성을 분석하였다. 분석 결과, C형 및 H형 이형벽체의 2축 상호작용은 모멘트 방향과 압축력 크기에 의하여 크게 영향을 받는 것으로 나타났다. 이러한 변수연구를 통하여 일정한 압축력에서 2축 모멘트강도의 상관관계를 나타내는 정규화된 컨투어 설계식을 제안하였다. 또한 실무에서 쉽게 활용할 수 있도록, 제안된 컨투어 설계식을 사용한 이형벽체 설계절차와 설계예제를 제시하였다.

• International Journal of Fluid Machinery and Systems
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• 제5권2호
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• pp.91-99
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• 2012

The Fighter aircraft transmission system consists of a light weight, High Speed Flexible Coupling (HSFC) known as Power Take-Off shaft (PTO) for connecting Engine gearbox (EGB) with Accessory Gear Box (AGB). The HSFC transmits the power through series of specially contoured metallic annular thin flexible plates whose planes are normal to the torque axis. The HSFC operates at high speed ranging from 10,000 to 18,000 rpm. The HSFC is also catered for accommodating larger lateral and axial misalignment resulting from differential thermal expansion of the aircraft engine and mounting arrangement. The contoured titanium alloy flexible plates are designed with a thin cross sectional profile to accommodate axial and parallel misalignment by the elastic material flexure. This paper investigates the effect of misalignment on the transmission characteristics of the HSFC couplings. A mathematical model for the HSFC coupling with misalignment has been developed for analyzing the torque transmission and force interaction characteristics. An extensive testing has been conducted for validating characteristics of the designed coupling under various misalignment conditions. With this the suitability of the model adapted for the design iteration of HSFC development is validated. This method will reduce the design iteration cycles of HSFC and can be extended for the similar development of flexible couplings.