• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.1 s.20
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• pp.29-33
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• 2004

Design of general steel structure had applied to achieve elastic designing concept so far. Because elastic design supposes that whole structure complies with elasticity formula so that achieve via allowable stress of material. It is concept that calculate stress distribution of construction about action external load and estimate load when the maximum stress reaches equally with allowable stress that is established by maximum safety load of the structure. But, absence that compose actuality structure by deal with external load increase small success surrender and structure hardness falls and structure in limited state finally on the whole as showing complicated process by interference between collapse and buckling under compression. Applied ANSYS (elasto-plasticity large deformation finite element method) to be mediocrity finite element program for analysis method and analysis control used in Newton-Raphson method & Arc-length method.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.57-62
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• 2013

A crack in a solid propellant increases the area of burning surface, which leads to excessive burning that causes motor failure. Therefore, it is necessary to evaluate fracture toughness of solid propellants. However, it is very difficult to measure fracture toughness of solid propellants because of the nonlinear mechanical behavior. In this study, evaluation of fracture toughness on a solid propellant was carried out under the assumption that the solid propellant is a linear viscoelastic material. Actual displacements from fracture toughness tests using CCT specimens were converted into pseudo-elastic displacements by using stress relaxation characteristics and fracture toughness was evaluated using ASTM E399 standard. Also, effects of test temperature and speed on the fracture toughness were considered.

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.517-525
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• 2018

The construction of super tall building which structure is RC and must be certainly considered on column shortening estimation and construction reflected concrete creep has been increased. Regarding the Fck 60~80MPa grade high strength concrete applied in the domestic super tall building project, the mechanical properties and creep deflection according to curing conditions(Drying creep/Basic creep) were reviewed in this research. Results of compressive strength and elastic modulus under sealed curing condition were 5% higher than unsealed condition and difference of results according to the curing condition was increased over time. Autogenous and drying shrinkage tendency showed adversely in the case of high strength concrete. Additionally, creep modulus under unseal curing condition was evaluated 2~3 times higher than sealed condition. Modified model of ACI-209 based on test result was applied to estimate long period shortening of vertical members(such as Core Wall/Mega Column) exactly, it is designed to modify and suggest the optimal creep model based on various data accumulated during construction, in the future.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.25-31
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• 2006

Over the years the investigation of behaviour of piles in groups connected to a cap in consolidating soil has attracted far less attention than the study of isolated piles in groups. In this paper, a series of three-dimensional numerical simulations have been performed to study the behaviour of pile groups connected to a cap in consolidating ground. Both elastic no-slip and elasto-plastic slip analyses were considered. Based on the analysis results, when piles were connected to a cap, tensile forces were developed near the pile head at the outer piles. Elastic solution and no-slip analysis over-predicted the tensile force near the pile head for outer piles. Relatively speaking, the number of piles in a group is more important than the pile spacing in terms of the influence of negative skin friction on the pile behaviour. The issue on the development of tensile forces on the pile head at the outer piles is perhaps needed to be carefully considered in the pile design to prevent the damages of the pile-cap connection.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.139-149
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• 2005

Post-local buckling behavior is a very important consideration in plastic and seismic design of steel structures. It describes the structural behavior up to the final collapse state. In order to assess the actual reliability of structures under severe repeated loading, such as strong earthquakes, it is necessary to evaluate the progressive cyclic deterioration of stiffness as well as the strength and energy dissipation capacity of the structures after local buckling happens. In this study, a simple analytical model developed for predicting post-local buckling behavior for cyclic and non-proportional loading histories, has been proposed. This analytical model uses the stress resultant model based on the two surface model. Analytical moment-curvature relationship using this model compare well with the experimental results in constant amplitude cycling, and linearized energy deterioration which is very important in seismic design can be predicted from the proposed model.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.683-692
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• 2012

The girders of cable stayed bridge are subjected to not only the bending moments but also additional compressive axial forces due to the horizontal components of cable forces. Because of these axial forces, the stiffness of girder can be decreased, and this problem should be considered especially for under-construction model rather than the full model. Korean domestic design specification suggests the linear elastic eigen value analysis for the stability problem of cable stayed bridges. However, this method cannot be applied to the under construction model because various geometric nonlinear characteristics cannot be considered. Therefore, in this study, 3 models which are assumed to be constructed by balanced cantilever will be considered experimentally and analytically to analyze the behavior of steel cable stayed bridges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.1020-1025
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• 2009

This study investigates elastic lateral-torsional buckling(LTB) of monosymmetric doubly stepped I-beams subjected to pure bending based on finite element analysis(FEA). The results from the FEA are used for new design stepped equation, Cst. The equations are compared with the results from the FEA. The comparison indicates that the new equation provides a good relation with the FEA results. The maximum difference between two results is of 11%. The new equation could be easily used to calculate the elastic lateral-torsional buckling moment resistance of monosymmetric stepped I-beams and to expand the new equation for developing LTB equations of monosymmetric stepped beams subjected to general loading conditions such as a concentrated load, distributed load, or a seres of concentrated load.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.365-373
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• 2008

Fiber Reinforced Polymer, FRP has a light weight, a high tensile strength based on design, non-electronic, non-magnetic, and rust-resistant feature, etc and many researches are being conducted recently on FRP in the construction area. Among them, GFRP (Glass Fiber Reinforced Polymer) is excellent in price competitiveness and is widely being used. However, since GFRP has a relative low modulus of elasticity and causes excessive deflection, the section must be large to be used as a structural component and an investigative review must be carried out in design to set the limit for deflection by the use load. Therefore, in order to solve the mentioned technical problems, this study suggested a section of a module form such that application of a large-scale section is possible. Also, to secure the low rigidity of FRP, this study developed a new FRP+ concrete composite girder form that confined the concrete. To identify the structural movement of the developed FRP+ concrete composite girder, shear strength test was carried out.

• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.27-37
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• 2006

Cemented Sand and Gravel (C.S.G) method has become increasingly popular in Japan and throughout the world as a construction method and material. This method is favorably used for cofferdam and large dam because a quarry and aggregate plant facility can be diminished. Also, this method can reduce construction cost, work duration and destruction of environment. In this paper, a methodology for C.S.G mix design based on so-called soil mechanics approach is proposed for trapezoid-shaped dam. The methodology consists of selection of a suitable aggregate, introduction of compaction method, processing to prepare standard specimens, and determination of mix portions. Also, unconfined compressive strength tests and large triaxial compression tests are performed. From the results of the test, correlation equation among strength, elastic modulus and unit cement is proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.735-742
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• 2006

In this study, the ultimate shear strength behavior of transversely stiffened curved web panels was investigated through nonlinear finite element analysis. It was found that if the transverse stiffener has a sufficient rigidity, then curved web panels used in practical designs are able to develop the postbuckling strength that is equivalent to that of straight girder web panels having the same dimensional and material properties. The nonlinear analysis results indicate that in order for curved web panels to develop the potential postbuckling strength. The rigidity of the transverse stiffener needs to be increased several times the value obtained from the Guide Specifications (AASHTO, 2003). However, in the case of thick web panels where the shear design is governed by shear yielding, the stiffener rigidity does not have to be increased. From the analysis results, a simple design formula is suggested for the rigidity of transverse stiffener under strength limit state.