• 한국공간구조학회논문집
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• 제6권3호
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• pp.111-121
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• 2006

들림형 보구조는 휨재와 뜬지주, 스트링으로 조합되는 구조로서, 스트링에 PS력을 도입하여 휨재의 응력과 변형을 조절함으로써 구조능력을 높이는 구조시스템이다. 기존의 연구결과와 실사례를 조사하여 들림형 보구조의 특성과 구조계획시 구성방식을 파악하였다. 그 결과, 연력도형의 보의 형상 및 높낮이 그리고 스트링의 sag설정, 평면배열, 뜬지주의 수와 구성이 설계인자로서 고려될 수 있음을 파악하였고, 실사례와 구조적 거동의 연구고찰을 통해 그 설계인자의 세부 구성방식을 나타내었다. 또한 들림형 보구조는 큰 부가하중이 작용할 때의 구조부담을 줄이기 위하여 부가하중에 대해 별도의 저항 메카니즘을 고안함으로써 구조효율을 높일 수 있는 방식이 고려될 수 있음을 보였다.

• 한국공간구조학회논문집
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• 제19권3호
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• pp.69-76
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• 2019

A Beam String Structure (BSS) is a type of hybrid structures, which is composed of upper structural members, lower strings, and struts. Due to the advantages that the pre-tensioned strings elicit pre-caber of the upper structural members, the deflection can be greatly reduced without increasing the structural member size. In this study, a two-way beam string structure is proposed to endure bi-directional loading. The two-way beam string structure consists of two cable parts, namely, sagging and arch-shaped cables. A parametric study is presented aimed at proposing design guide lines of the two-way beam string structures. Numerical finite element analyses through the ABAQUS package were implemented to obtain their behaviors.

• Smart Structures and Systems
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• 제12권3_4호
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• pp.327-344
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• 2013

Beam string structure (BSS) is introduced as a new type of hybrid prestressed string structures. The composition and mechanics features of BSS are discussed. The main principles of wavelet packet transform (WPT), principal component analysis (PCA) and support vector machine (SVM) have been reviewed. WPT is applied to the structural response signals, and feature vectors are obtained by feature extraction and PCA. The feature vectors are used for training and classification as the inputs of the support vector machine. The method is used to a single one-way arched beam string structure for damage detection. The cable prestress loss and web members damage experiment for a beam string structure is carried through. Different prestressing forces are applied on the cable to simulate cable prestress loss, the prestressing forces are calculated by the frequencies which are solved by Fourier transform or wavelet transform under impulse excitation. Test results verify this method is accurate and convenient. The damage cases of web members on the beam are tested to validate the efficiency of the method presented in this study. Wavelet packet decomposition is applied to the structural response signals under ambient vibration, feature vectors are obtained by feature extraction method. The feature vectors are used for training and classification as the inputs of the support vector machine. The structural damage position and degree can be identified and classified, and the test result is highly accurate especially combined with principle component analysis.

• 한국공간구조학회논문집
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• 제13권4호
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• pp.49-56
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• 2013

Beam string structures(BSS) are one kind of efficient structure system because the bending moment in the beams is reduced greatly through the struts and the strings. As the struts in BSS are used as middle supports to the beam and always in compression, the buckling of the struts should be avoided. This paper investigates the lateral buckling of the struts in BSS. Firstly, the strut of a one-strut BSS is simplified into an analytical model by considering load is formulated and some special cases of the model are analyzed. Finally, the lateral buckling load of the strut is numerically examined by means of parameter studies. It is known that, because on end of the struts is jointed to the beam while the other end is connected to the strings, the buckling of the struts not only depends on the length of the struts and the stiffness of the joints, but also depends on the rise and the lateral stiffness of the beam, the layout of the strings and the number of the struts.

• Structural Engineering and Mechanics
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• 제35권1호
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• pp.67-82
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• 2010

The beam string structure (BSS) has been widely applied in large span roof structures, while no analytical solutions of BSS were derived for it in the existing literature. In the first part of this paper, calculation formulas of displacement and internal forces were obtained by the Ritz-method for the most commonly used arc-shaped BSS under the vertical uniformly distributed load and the prestressing force. Then, the failure mode of BSS was proposed based on the static equilibrium. On condition the structural stability was reliable, BSS under the uniformly distributed load would fail by tensile strength failure of the string, and the beam remained in the elastic or semi-plastic range. On this basis, the limit load of BSS was given in virtue of the elastic solutions. In order to verify the linear elastic and limit state solutions proposed in this paper, three BSS modal were tested and the corresponding elastoplastic large deformation analysis was performed by the ANSYS program. The proposed failure mode of BSS was proved to be correct, and the analytical results for the linear elastic and limit state were in good agreement with the experimental and FEM results.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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• pp.127-132
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• 2008

최근, 지진하중에 대한 대공간구조무의 응답특성에 관한 연구가 다수 수행되었으며, 라이즈/스팬비가 큰 지붕구조에 대하여서는, 수평지진입력에 대한 역대칭모드의 증폭이 지배적으로 됨이 지적되었다. 본 연구에서 제안하는 정적지진하중평가법에서는, 라이즈가 있는 지붕구조의 내진설계를 수행함에 있어, 허용응력도설계법을 따르며, 그림1과 같이 설계용전단력를 지붕면에 따라 부가하는 정적평가법을 채용하고 이를 정적지진하중평가법이라 부르기로 한다. 본 논문의 구성으로서는, 정적평가법의 개념 및 정적설계식의 유도과정을 나타내고, 라이즈/스팬비가 서로 다른 지붕구조물을 대상으로 하여, 본 평가법에 의한 결과와 정적응답해석을 수행한 결과를 비교하고, 정적평가법의 타당성에 대하여 검토한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.288.2-288.2
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• 2014

InP quantum dots were grown by using the molecular beam epitaxy technique. Quantum dots are connected and composed string-like one-dimensional structure due to the strain field along [110] crystal direction. Two prominent photoluminescence transitions from normal quantum dots and string-like one-dimensional structure were observed which show strong optical anisotropy along [1-10] and [110] crystal directions. Both peaks also showed blue-shift while rotating emission polarization from [1-10] to [110] direction. Such optical transition behaviors are the consequence of the valence band mixing caused by strain field along the [110] crystal direction.

• Structural Engineering and Mechanics
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• 제36권5호
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• pp.643-667
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• 2010

The classical flexibility difference method detects damage by observing the difference of conventional deflection flexibility matrices between pre- and post-damaged states of a structure. This method is not able to identify multiple damage scenarios, and its criteria to identify damage depend upon the boundary conditions of structures. The key point behind the inability and dependence is revealed in this study. A more feasible flexibility for damage detection, the Angle-between-String-and-Horizon (ASH) flexibility, is proposed. The physical meaning of the new flexibility is given, and synthesis of the new flexibility matrix by modal frequencies and translational mode shapes is formulated. The damage indicators are extracted from the difference of ASH flexibility matrices between the pre- and post-damaged structures. One feature of the ASH flexibility is that the components in the ASH flexibility matrix are associated with elements instead of Nodes or DOFs. Therefore, the damage indicators based on the ASH flexibility are mapped to structural elements directly, and thus they can pinpoint the damaged elements, which is appealing to damage detection for complex structures. In addition, the change in the ASH flexibility caused by damage is not affected by boundary conditions, which simplifies the criteria to identify damage. Moreover, the proposed method can determine relatively the damage severity. Because the proposed damage indicator of an element mainly reflects the deflection change within the element itself, which significantly reduces the influence of the damage in one element on the damage indicators of other damaged elements, the proposed method can identify multiple damage locations. The viability of the proposed approach has been demonstrated by numerical examples and experimental tests on a cantilever beam and a simply supported beam.

• Smart Structures and Systems
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• 제20권5호
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• pp.563-572
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• 2017

The safety of structures is closely associated with the structural out-of-plane behavior. In particular, long and slender beam structures have been increasingly used in the design and construction. Therefore, an evaluation of the lateral and torsional behavior of a structure is important for the safety of the structure during construction as well as under service conditions. The current contact measurement method using displacement meters cannot measure independent movements directly and also requires caution when installing the displacement meters. Therefore, in this study, a vision-based system was used to measure the in-plane and out-of-plane displacements of a structure. The image processing algorithm was based on reference objects, including multiple targets in Lab color space. The captured targets were synchronized using a load indicator connected wirelessly to a data logger system in the server. A laboratory beam test was carried out to compare the displacements and rotation obtained from the proposed vision-based measurement system with those from the current measurement method using string potentiometers. The test results showed that the proposed vision-based measurement system could be applied successfully and easily to evaluating both the in-plane and out-of-plane movements of a beam including twisting rotation.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2005년도 춘계학술발표회 및 정기총회 2권1호(통권2호)
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• pp.52-66
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• 2005

Tension and Membrane have the potential to enable the realization of lightweight structures that have the attractive features of structures efficiency and aesthetical expression. Compared with pure (thorough-bred) tension structures such as cable net, air dome and tensegrity, so called hybrid tension structures such as beam string, tensegric system and other mixed structures have Potential still to be realized. After synnaruzubg the simple definition of tensegric structure, some holistic designs for hybrid tension structures completed recently in the author's practice are given.