• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.57-66
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• 2007

The membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and happen large deformation phenomenon. Therefore, in this paper, we investigate the convergence of solution and the speed according to the control variables and the method of shape analysis.

• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.153-165
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• 2007

Flexible structure uses a material with strong axial stiffness and small bending stiffness as its major structural material so it is very sensitive to initial stiffness. Therefore, the self-formation process which accomplishes a form in the natural world is grasped and it is as well investigated and classified the type of modeling techniques which are available to find the shapes of soft structures. Accordingly, for analysis and design of flexible structure, three-step analysis such as shape analysis, stress-deformation analysis, cutting pattern generation and constructional analysis is required unlike the existing stiff structure. In this study, suggest that minimize the error of side curvatures by the triangle Re-mesh pattern and draw the cutting pattern generation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.4
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• pp.274-286
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• 1996

Two-dimensional flexible body analysis (hydroelasticity theory) is adopted to a very large floating structure that may be multimodule and extend in the longitudinal direction. The boundary-element method (BEM) and Green function method(GFM) are used to obtain the hydrodynamic coefficients. The structure is considered to be a flexible beam responding to waves in the vertical direction and a consistent formulation for the hydrostatic stiffness is derived. The resulting coupled equations of motion are solved directly. Two designs of the module connectors are considered: a rotationally-flexible hinge connector, and a rotationally-rigid connector Numerical examples are presented to an integrated system of semi-submersibles. The analysis provides basic motions and section forces, which are useful to develop an understanding of the fundamental modes of displacement and force amplitudes for which multi-module VLFSs must be designed. The results show that while the hinge connectors result in greater motion, the rigid connectors increase substantially the sectional moments.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.137-146
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• 2007

Numerical analyses are performed to show the effect of stiffening facade riggers on the behavior of the structure and to investigate the optimum locations of facade riggers. Optimum locations of the facade riggers to minimize the drift at the top of the structure are obtained by maximizing the drift reduction caused by the facade riggers and are significantly influenced by the bending and shear stiffnesses of the braced frame and facade riggers. Three standard load cases of uniformal and triangularly distributed lateral loads as well as a lateral point load at the top of the structure are considered in this paper Optimum locations of facade riggers are plotted as functions of nondimensional relative stiffness parameters ${\omega}$ and ${\beta}$ for structures with one to four riggers. Although the analysis presented herein is based on certain simplifying assumptions, it is believed that the results do provide sufficiently accurate information for determining the optimum locations of facade riggers in highrise structures.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.85-96
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• 2016

Double split tee connection has various strength, stiffness, and energy dissipation capacity according to changes of thickness of T-stub flange and gauge distance, number, and diameter of high-strength bolt. If the double split tee connection is applied to a low- or medium-rise steel structure, a shear tab can't be applied for supporting shear force because of geometrical limitation. So it is required to propose details of improved double split tee connection to support shear force as well as flexural force. This research was performed to see if enough rotational stiffness is found when the double split tee connection without shear tab which was obtained through analytic and experimental researches by Yang et al. is applied to a low- or medium-rise steel structure. Also, it was seen if the low- or medium-rise steel structure having double split tee connection without shear tab has safe structural behavior, as well as material saving effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.107-114
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• 2018

In this study, the damage detection method is proposed for the rotational stiffness of connections in steel moment frames by using artificial neural network(ANN). The flexural moment of columns, natural frequencies, modeshapes are used for the input layer in ANN while the damage index, that signify the damage level, is used for the output layer in ANN. The 5-story steel moment frame as an example structure is used to generate the train and test data. Total number of damage scenarios considered is 829. From the results of application, it is shown that the proposed method can accurately estimate the location and level of damages.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.4
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• pp.639-647
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• 2002

A simplified analytical procedure is presented to estimate the reduction of elastic lateral stiffness of steel moment frames arising from the radius-cut dogbone weakening. With the original radius-cut dogbone shape, it is almost impossible or too complicated to integrate analytically the mathematical expressions encountered when applying the conjugate beam method to compute the beam deflection component. In this study, the problem is circumvented by replacing the original radius-cut dogbone with an equivalent dogbone of constant width. The equivalence between the two is established by imposing an equal dogbone elongation criterion. This approach is justified by using a calibrated finite clement analysis. Then, the elastic lateral deflection components from the column, panel zone, and beam are derived for a typical beam-column subassembly. The derived results can be used to evaluate the reduction of the frame lateral stiffness. Case studies conducted within some practical ranges of frame configurations show that the reduction in frame lateral stiffness due to the presence of dogbone cut is on the order of 1 to 2 percent and is reasonably negligible in practical sense.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.148-155
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• 2009

A remarkable discrepancy of lateral deformation of shear wall structures for seismic loads due to a rigid diaphragm assumption without floor slab modelling asks a study how much effective the slab stiffness ratio is to the lateral behaviour. Typical shear wall type 15 stories structure is selected to analysis using MIDAS-ADS2008 commercial softwares modelling three types; 1) rigid diaphragm (RD model) 2) considered out-of plane slab flexural stiffness (DB model), and 3) considered in and out of plane slab flexural stiffness (SRC model). Based on National Code of KBC2005, the Equivalent Static and Response Spectrum seismic analysis are undertaken to compare each responses of the three models. The differences of lateral responses due to the three slab stiffness ratios applied on the models are compared and discussed.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.59-66
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• 2008

This study is about manufacturing and producing girder, which is an essential component of bridge structure, in a composite of FRP + concrete. This has a higher competitive power in price than steel girder. The girder used in this study is made of glass fiber which has a lower elastic modulus than steel and thus has some technical limitations such as excessive deflection compared to steel girder and lack of production facilities in FRP production companies to make a large-section component material. Thus, this study suggested a section of a new module that will allow for applying a large section in order to solve the technical difficulties mentioned above and to secure low stiffness of FRP, developed a new FRP+concrete composite girder that is filled with the appropriate amount of concrete. To identify the structural behavior of this FRP+concrete composite girder, experiments were conducted to measure its flexural strength according to the difference in the strength of confined concrete and the existence of stud. The results of the flexural strength test confirmed the composite effect from confining concrete and the effect of increase in strength proportional to the strength of concrete. In developing FRP+concrete composite girder, NDT study was also conducted to analyze the interface characteristics of concrete and FRP.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.421-432
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• 2009

In this study, push-out and static loading tests were conducted to evaluate the behavioral characteristics of composite beams with a perfobond rib shear connector. The shear capacity of the perfobond rib was found to be proportional to its concrete strength, which is in turn affected by the increase in the concrete end-bearing strength and concrete dowel action to resist the shear force. The relative slips of the push-out specimen, however, which was used to assess the ductility of the shear connector, increased to some extent, but it no longer increased when it reached the critical concrete strength because of the flexibility of the transverse rebar in the rib hole. The static-loading-test results revealed a crack on the concrete slab in the composite beam with a perfobond rib on the side of the rib hole and transverse rebar for the applied moment and shear force to the rib hole, depending on the static loading. The shear resistance characteristics of the perfobond rib shear connector were found to resist the shear force from the relative slip on the interface of the composite beam. Thus, the sectional effect of the shear connector to the composite beam with a perfobond rib should be considered when designing the composite beam because the behavior of the composite beam can change owing to the shear connector.