• 한국자동차공학회논문집
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• 제7권6호
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• pp.270-278
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• 1999

This paper describes the collapse characteristics of the rectangular tube under eccentric compressive load. Overall buckling stress and bifurcation criterion (slenderness ration)are investigated. modified secant formula(MSF) is proposed to decide overall buckling stress. The bifurcation criterion which can distinguish between the local and overall buckling mode shapes is suggest by equating the local and overall buckling stresses. Additionally the effect of initial imperfection on bifurcation criterion is investigated.

• 대한기계학회논문집A
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• 제24권1호
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• pp.16-28
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• 2000

The steady rotating flows in eccentric annulus has been studied by a numerical method based on the spectral collocation method. The inner cylinder has a constant angular velocity while the outer on e is stationary. Flow between eccentric cylinders is of considerable technical importance as it occurs in journal bearings. In the present work, the governing equations for laminar flow are expressed as Navier-Stokes equations, including the non-linear convection terms. The solutions were utilized i, estimate the effects of the nonlinear terms on the load acting on the rotating cylinder. Based on the half and the full Sommerfeld methods, the load on the rotating cylinder is evaluated with eccentricity, by integrating the pressure and skin friction around the cylinder. The attitude angle and Sommerfeld reciprocal are calculated from the load. Also, the torque on the rotating inner cylinder was calculated. considering the skin friction. The attitude angle and Sommerfeld reciprocal are decreased with eccentricity. Viscous damping coefficient due to the skin friction becomes larger with decreasing the annular space. It is found the non-linear effects of the convection terms on the flow and the load are important. especially on the attitude angle, for relatively wide annular configurations however, the effects on those are minor for very narrow annular ones.

• Current Optics and Photonics
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• 제7권4호
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• pp.337-344
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• 2023

Three-point bending is the main method for measuring the elastic modulus of a thin plate. Although various displacement transducers may be used to measure the bending, these are single-point measurements, and it is difficult to eliminate the error caused by eccentric load and shear force. Error-correction models for the elastic modulus of quartz glass using digital speckle interferometry are proposed for eccentric load and shear force. First, the positional misalignment between maximum deflection and load is analyzed, and the error caused by eccentric load is corrected. Then, the additional displacement caused by shear force at different positions of the quartz glass plate is explored. The effect of shear deformation is also corrected, by measuring two points. Since digital speckle interferometry has the advantage of full-field measurement, it can simultaneously obtain deflection data for multiple points to realize error correction. Experimental results are presented to demonstrate that the proposed model can effectively correct the measurement error of the elastic modulus.

• 한국강구조학회 논문집
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• 제15권6호통권67호
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• pp.683-691
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• 2003

최근, 철골구조, 철골 철근콘크리트 구조 및 합성구조의 주각부는 국부적으로 제한된 부분에 큰 집중하중이 작용하고, 이 하중은 베이스 플레이트를 통하여 철근콘크리트 기초에 전달하게 된다. 따라서 철골구조 및 철골 철근콘크리트 구조의 설계에서 큰 축력을 받는 주각부의 지압강도를 정확히 평가하기가 매우 어렵다. 철골주각부는 역학적 특성이 다른 재료의 접합부로 설계 및 시공상 제약을 받게 되고, 응력전달도 매우 복잡하다. 특히, 구조설계시 지압강도의 적절한 평가는 무엇보다 중요하다. 지압강도에 영향을 미치는 요소는 지압응력을 받는 부재의 형태 및 재료, 하중의 작용형태, 지압면에서의 마찰구속력, 철근보강, 건조수축 등 매우 많다. 지압강도에 대한 대부분의 실험 및 연구에서는 중심축력을 받는 주각부에 대한 연구를 수행하였다. 그러나, 실제 철골주각부 설계에서는 일축편심 또는 이축편심축력을 받는 경우가 많이 있다. 본 연구에서는 베이스플레이트에 작용하는 편심축력과 편심거리에 따른 지압강도의 변화 및 실험체의 파괴형태에 대하여 검토하였고, 편심축력 작용시 지압강도 산정방법을 제시하였다.

• 한국강구조학회 논문집
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• 제11권1호통권38호
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• pp.89-98
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• 1999

본 연구는 콘크리트충전 각형강관 기둥의 중심 및 편심압축 실험을 통해 비탄성역에서의 좌굴내력을 구하고, 그 결과를 비교 분석하여 기둥의 각 변수에 따른 내력 및 변형능력에 미치는 영향을 종합적으로 파악하며, 각국의 규준식과 비교하여 새로운 내력식을 제안하여 콘크리트충전 각형강관 기둥을 이용한 고층구조시스템의 개발에 필요한 구조역학적 정보를 제공하고, 향후 국내의 콘크리트충전 강관구조 규준 제정에 필요한 기초 자료를 제시하는데 그 목적이 있다.

• Earthquakes and Structures
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• 제17권6호
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• pp.623-633
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• 2019

A large number of available concrete buildings designed only considering gravity load that require seismic rehabilitation because of failure to meet plasticity criteria. Using steel bracings are a common type of seismic rehabilitation. The eccentric bracings with vertical link reduce non-elastic deformation imposed on concrete members as well as elimination of probable buckling problems of bracings. In this study, three concrete frames of 10, 15, and 20 stories designed only for gravity load have been considered for seismic improvement using performance-based plastic design. Afterwards, nonlinear time series analysis was employed to evaluate seismic behavior of the models in two modes including before and after rehabilitation. The results revealed that shear link can yield desirable performance with the least time, cost and number of bracings of concrete frames. Also, it was found that the seismic rehabilitation can reduce maximum relative displacement in the middle stories about 40 to 80 percent. Generally, findings of this study demonstrated that the eccentric bracing with vertical link can be employed as a suitable proxy to achieve better seismic performance for existing high rise concrete frames.

• Structural Engineering and Mechanics
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• 제8권1호
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• pp.85-102
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• 1999

With the advent of computer, the finite element method has become a most powerful numerical method for structural analysis. However, bridge designers are reluctant to use it in their designs because of its complex nature and its being time consuming in the preparation of the input data and analyzing the results. This paper describes the development of a computer based finite element model using the idea of eccentric beam elements for the analysis of slab-on-girder bridges. The proposed method is supported by a laboratory test using a reinforced concrete bridge model. Other bridge analytical schemes are also introduced and compared with the proposed method. The main aim of the comparison is to prove the effectiveness of the shell and eccentric beam modelling in the studies of lateral load distribution of slab-on-girder bridges. It is concluded that the proposed finite element method gives a closer to real idealization and its developed computer program, SHECAN, is also very simple to use. It is highly recommended to use it as an analytical tool for the design of slab-on-girder bridges.

• Advances in concrete construction
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• 제10권2호
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• pp.151-159
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• 2020

An experimental study on the stress-strain relation of PVC-CFRP confined reinforced concrete columns subjected to eccentric compression was carried out. Two parameters, such as the CFRP strips spacing and eccentricity of axial load, were considered. The experimental results showed that all specimens failed by compressive yield of longitudinal steel bar and rupture of CFRP strips. The bearing capacity of specimen decreases as the eccentricity or the CFRP strips spacing increases. The stress-strain relation of specimens undergoes two stages: parabolic and linear stages. In the parabolic stage, the slope of stress-strain curve decreases gradually as the eccentricity of axial loading increases while the CFRP strips spacing has little effect on the slope of stress-strain curve. For the linear stage, the slope of stress-strain curve decreases as the eccentricity of axial load or the CFRP strips spacing increases. A model for predicting the stress-strain relation of columns under eccentric compression is proposed and it agrees well with various test data.

• 한국산학기술학회논문지
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• 제15권3호
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• pp.1749-1755
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• 2014

진동해머에 의해 시공되는 말뚝의 해석기법을 개발하고 매개변수연구를 수행하여 개발된 해석기법의 신뢰성을 평가해보았다. 편심모멘트와 진동수에 따른 매개변수해석을 통해 구한 가속도를 비교분석해 본 결과 최대가속도의 크기는 대략적으로 편심모멘트에 비례하였으며 진동수의 제곱에 비례하였다. 또한 변위진폭은 편심모멘트에 비례하는 결과를 나타내었고 진동수에는 거의 영향을 받지 않았는데 이러한 경향은 공운전시의 거동특성과 유사하다. 매개변수해석을 통해 구한 동적 하중전이곡선을 비교해 볼 때 편심모멘트와 진동수의 크기에 관계없이 최대 동적단위선단저항력의 크기는 동일하였으며 최대 동적단위주면마찰력의 크기는 편심모멘트에 영향을 받으나 진동수와는 무관하였다. 매개변수해석결과를 종합적으로 비교분석해 볼 때 개발된 해석기법은 합리적인 해석결과를 보인다고 볼 수 있다.

• Computers and Concrete
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• 제25권1호
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• pp.1-14
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• 2020

This study presents applications of the multivariate adaptive regression splines (MARS) method for predicting the ultimate loading carrying capacity (N_u) of rectangular concrete-filled steel tubular (CFST) columns subjected to eccentric loading. A database containing 141 experimental data was collected from available literature to develop the MARS model with a total of seven variables that covered various geometrical and material properties including the width of rectangular steel tube (B), the depth of rectangular steel tube (H), the wall thickness of steel tube (t), the length of column (L), cylinder compressive strength of concrete (f'_c), yield strength of steel (f_y), and the load eccentricity (e). The proposed model is a combination of the MARS algorithm and the grid search cross-validation technique (abbreviated here as GS-MARS) in order to determine MARS' parameters. A new explicit formulation was derived from MARS for the mentioned input variables. The GS-MARS estimation accuracy was compared with four available mathematical methods presented in the current design codes, including AISC, ACI-318, AS, and Eurocode 4. The results in terms of criteria indices indicated that the MARS model was much better than the available formulae.