• 한국공간구조학회논문집
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• 제8권3호
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• pp.45-51
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• 2008

단층 래티스 돔은 경량이면서도 높은 강성을 가지므로 대공간 구조물로서 유리하며, 이 구조물은 기둥 없이 널은 공간을 확보해야하는 구조적 특성으로 인하여 시공시 불안정 현상이 발생할 수 있다. 현재 국내에서 대공간 지붕구조물의 설치 방법으로 가장 많이 도입되고 있는 Erection공법은 Block공법이며, 이 공법은 지상에서 조립한 대공간 지붕 골조를 크레인 등으로 소정의 위치까지 들어 올려 지붕구조를 완성해 가는 설치 공법이다. Block 공법에 있어서 인양할 포인트를 선정하는 작업은 대단히 중요하다. 즉, 인양 시 골조의 변형과 좌굴 등에 대해서 가장 안전하고 경제적인 절점을 인양 포인트로 선정할 필요가 있다. 따라서 본 연구에서는 가장 안전하고 경제적인 Erection을 위한 기초자료를 얻기 위하여 삼각형 네트워크를 갖는 단층 래티스 돔의 Erection 시 인양 포인트에 따른 구조물의 거동 및 좌굴 특성을 연구하는데 그 목적이 있다. 얻어진 결론은 1) 돔의 높이 H가 작을수록 인양위치에 따른 좌굴내력의 영향이 큰 것을 알 수 있었으며, 반대로 돔의 높이 H가 클수록 인양위치에 따른 좌굴내력의 영향은 미미한 것을 알 수 있었다. 2) 인양 위치에 관계없이 인양로프 길이에 따른 좌굴내력의 영향은 크지 않은 것을 알 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.69-72
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• 2005

For reinforced concrete column under sustained loads, the member suffers additional lateral deflection due to creep. This deflection leads to additional bending in the member, which in turn causes the column to deflect still further. Therefore the secondary moment due to additional deflection causes an increase in primary moment and the strength of column is reduced. And also creep buckling may occur. On this study, nonlinear analysis of reinforced concrete long column including crack effects is carried out and then the strength of long column is revaluated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.480-485
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• 1996

A numerical method for perdicting the behavior of a reinforced concrete column under biaxial loading is proposed, using the layered finite element method. Concrete is assumed to exhibit strain softening and steel reinforcement is elastic-plastic. The bending theory assumptions are used and bond slip of reinforcement is meglected. To perdict the entire load-deformation characteristics, displacement control method is used. This method consider not only combined effect due to axial load and bending moment but also that due to bending moments. Predicted behaviors of reinforced concrete columns under biaxial loading through the numerical method proposed in this study show good agreements with test results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.419-422
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• 2005

Prestressed composite girder bridges with concrete infilled steel tube at negative flexural moment region takes the advantages provided due to the interactive reaction in the steel tube and concrete interface layer, enhancing local buckling resistance and the concrete strength provided by the lateral confining effect of concrete. Two beams were tested to examine ultimate behaviors of prestressed composite girder bridges subjected to negative flexural moment. The experimental observations of the Prestressed composite girder bridges subjected to positive flexural moment are investigated and compared to the numerical results obtained by sectional analysis method, and 1-D. and 3-D. finite element analysis methods.

• 대한토목학회논문집
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• 제30권6A호
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• pp.503-512
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• 2010

하중-저항계수 설계법에서 조밀단면은 휨모멘트에 의하여 특정단면이 소성모멘트에 도달하기 전에 복부판과 플랜지에 국부좌굴 및 거더의 횡비틈좌굴이 발생하지 않는 단면으로 정의하고 있다. AASHTO LRFD(2007)에서는 수평보강재를 갖지 않는 단면에 관해서만 조밀단면을 만족하는 복부판의 세장비 규정을 제시하고 있다. 복부판에 설치하는 수평보강재의 역할은 휨 좌굴강도를 증가시키는 것이다. 비록 비보강된 복부판이 조밀단면의 기준을 만족하지 못한다고 할지라도, 적당한 수평보강재를 설치한다면 복부판의 좌굴을 방지할 수 있을 것이다. 그러므로 복부판은 소성모멘트에 도달할 수 있을 것이다. 그러나 AASHTO LRFD(2007)에서는 수평보강재를 설치한 복부판이 조밀단면을 만족하지 못하는 이유에 관하여 분명하게 설명하고 있지 않다. 본 연구에서는 수평보강재를 설치한 복부판에서의 휨에 의한 좌굴과 극한강도거동을 선형과 비선형 유한요소법을 통하여 검토하였다. 비록 조밀단면의 세장비를 만족하지 못하는 복부판이라고 할지라도, 충분한 강성과 적절한 위치에 수평보강재로 보강하면 소성모멘트에 도달할 수 있다는 것을 알아냈다. 비선형해석의 분석을 통해 수평보강재를 갖는 복부판의 조밀단면을 만족하는 새로운 세장비 조건식을 제안하였다.

• 한국해양공학회지
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• 제21권1호
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• pp.51-58
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• 2007

This study on the effects of local wall-thinned location on the fracture behavior of pipes was carried out, and the results were compared with the analytical results. Local wall-thinning for the bending test was machined with various sizes on the outside of pipes, in order to simulate the metal loss, due to erosion/corrosion. In addition, we had carried out FE analysis for the pipes with local wall thinning on the inside, and its results were comparatively studied with that of the outside. Three-dimensional elasto-plastic analyses were able to accurately simulate fracture behaviors of inner or outer wall thinning. Fracture types, obtained from the experiments and analyses, could be classified into ovalization, local buckling and crack initiation, depending on the thinned length and thinned ratio. Based on the results, the fracture behaviors of pipes with the outer wall thinning can be applied to estimate the fracture behaviors of pipes with the inner wall thinning.

• Structural Engineering and Mechanics
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• 제74권2호
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• pp.201-214
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• 2020

This study aims at evaluating composite moment frame structures (CFS) using wavelet analysis of the displacement behavior of these structures. Five seismic damage mitigation systems' models of 9-story CFS are examined namely, basic (Model 1), reinforced (Model 2), buckling restrained braced (BRB) (Model 3), lead rubber bearing (LRB) (Model 4), and composite (Model 5) moment frames. A novel integration between continuous and discrete wavelet transforms is designed to estimate the wavelet power energy and variance of measurements' behaviors. The behaviors of the designed models are evaluated under influence of four seismic loads to study the dynamic performance of CFS in the frequency domain. The results show the behaviors of models 3 and 5 are lower than other models in terms of displacement and frequency performances. Model 3 has been shown lower performances in terms of energy and variance wavelets along the monitoring time; therefore, Model 3 demonstrates superior performance and low probability of failure under seismic loads. Furthermore, the wavelet variance analysis is shown a powerful tool that can be used to assess the CFS under seismic hazards.

• Computers and Concrete
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• 제25권6호
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• pp.485-495
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• 2020

This paper, presents the dynamic and stability analysis of the simply supported single walled Carbon Nanotubes (SWCNT) reinforced concrete beam on elastic-foundation using an integral first-order shear deformation beam theory. The condition of the zero shear-stress on the free surfaces of the beam is ensured by the introduction of the shear correction factors. The SWCNT reinforcement is considered to be uniform and variable according to the X, O and V forms through the thickness of the concrete beam. The effective properties of the reinforced concrete beam are calculated by employing the rule of mixture. The analytical solutions of the buckling and free vibrational behaviors are derived via Hamilton's principle and Navier method. The analytical results of the critical buckling loads and frequency parameters of the SWCNT-RC beam are presented in the form of explicit tables and graphs. Also the diverse parameters influencing the dynamic and stability behaviors of the reinforced concrete beam are discussed in detail.

• Structural Engineering and Mechanics
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• 제11권1호
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• pp.35-48
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• 2001

The objective of this study is to investigate the stability behavior of steel cable-stayed bridges by comparing the buckling loads obtained by means of finite element methods with eigen-solver. In recent days, cable-stayed bridges dramatically attract engineers' attention due to their structural characteristics and aesthetics. They require a number of design parameters and present a high degree of static indetermination, especially for long span bridges. Cable-stayed bridges exhibit several nonlinear behaviors concurrently under normal design loads due to the individual nonlinearity of substructures such as the pylons, stay cables, and bridge deck, and their interactions. The geometric nonlinearities arise mainly from large displacements of cables. Strong axial and lateral forces acting on the bridge deck and pylons cause structural nonlinear behaviors. The interaction is among the substructures. In this paper, a typical three-span steel cable-stayed bridge with a variety of design parameters has been investigated. The numerical results indicate that the design parameters such as the ratio of $L_1/L$ and $I_p/I_b$ are important for the structural behavior, where $L_1$ is the main span length, L is the total span length of the bridge, $I_p$ is the moment of inertia of the pylon, and $I_b$ is the moment of inertia of the bridge deck. When the ratio $I_p/I_b$ increases, the critical load decreases due to the lack of interaction among substructures. Cable arrangements and the height of pylon are another important factors for this type of bridge in buckling analysis. According to numerical results, the bridges supported by a pylon with harp-type cable arrangement have higher critical loads than the bridges supported by a pylon with fan-type cable arrangement. On contrary, the shape of the pylon does not significantly affect the critical load of this type of bridge. All numerical results have been non-dimensionalized and presented in both tabular and graphical forms.

• 한국강구조학회 논문집
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• 제18권1호
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• pp.71-80
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• 2006

강판 전단패널의 거동이 일반연강 (S400) 을 이용한 실험 및 해석으로 고찰되었다. 강판 전단패널은 작은 하중에서 좌굴을 하지만, 패널의 전단극한강도는 인장력 작용에 의한 강판 전단패널의 좌굴후 강도에 의해 좌우된다. 그러나, 설계상에서 강판 전단패널의 성능은 강판 전단패널의 탄성좌굴강도에 국한된다. 캐나다 극한강도 설계 규준 (CAN/CSA-S16.1-94)은 스트립 모델을 이용한 박강판 전단패널의 해석을 위한 절차를 규정하고 있다. 본 논문에서는 실험결과와 스트립모델 해석 결과를 이용하여 강판 전단패널의 구조성능을 평가하였다.