• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.5
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• pp.249-259
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• 2019

To study the seismic resistance of the shear capacity of the RC beam-column joints of two-story and four-story RC buildings, sample buildings are designed with ordinary moment resisting frame. For the shear capacity of joints, the equations of FEMA 356 and NZ seismic assessment are selected and compared. For comparison, one group of buildings is designed only for gravity loads and the other group is designed for seismic and gravity loads. For 16 cases of the designed buildings, seismic performance point is evaluated through push-over analysis and the capacity of joint shear strength is checked. Not only for the gravity designed buildings but also for seismic designed buildings, the demand of joint shear is exceeding the capacity at exterior joints. However, for interior joint, the demand of joint shear exceeds the capacity only for one case. At exterior joints, the axial load stress ratio is lower than 0.21 for gravity designed buildings and 0.13 for seismic designed buildings.

• Wind and Structures
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• v.10 no.4
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• pp.347-366
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• 2007

Guyed masts subjected to turbulent winds exhibit complex vibrations featuring many vibration modes, each of which contributes to various structural responses in differing degrees. This dynamic behaviour is further complicated by nonlinear guy cable properties. While previous studies have indicated that conventional frequency domain methods can reliably reproduce load effects within the mast, the system linearization required to perform such an analysis makes it difficult to relate these results directly to corresponding guy forces. As a result, the estimation of peak load effects arising jointly from the structural action of the mast and guys, such as leg loads produced as a result of guy reactions and mast bending moments, is uncertain. A numerical study was therefore undertaken to study peak load effects in a 295 m tall guyed mast acted on by simulated turbulent wind. Responses calculated explicitly from nonlinear time domain finite element analyses were compared with approximate methods in the frequency domain for estimating peak values of selected responses, including guy tension, mast axial loads and mast leg loads. It was found that these peak dynamic load effects could be accurately estimated from frequency domain analysis results by employing simple, slightly conservative assumptions regarding the correlation of related effects.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.97-104
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• 2015

Compared with a strong axial rigidity due to large intial tension, cable has a weak laterally flexural rigidity. A variety of dynamic loads such as traffic loads and wind loads etc. cause the cables to vibrate significantly and affect the mechanical properties and the performance of cables. Therefore, vibration reduction design is an urgent task to control the vibration of cable-supported bridges. Because a various kind of dampers have shown to reduce the amplitude and duration time of vibration of cable from measured date in field test, damper can be considered that it is effective device significantly to reduce the amplitude and duration time in vibration of cable. Vibration characteristics of cable can change according to manufacturing method and type of established form, and damper has been designed according to distribution of natural frequencies and vibration modes. In this study, numerical analysis is used to show the reduction effects of vibrations and present the design of damper for vibration reduction of cable.

• Tunnel and Underground Space
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• v.11 no.2
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• pp.96-108
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• 2001

A concrete lining of NATM tunnel is the final product of a process that involves planning and evaluation of user needs, geotechnical investigations, analysis of ground-lining interaction, construction, and observations and modifications during construction. The designer must consider the lining in context of the many function, construction, and geotechnical requirements. Also, the loss of supporting capacity of shotcrete lining due to poor rock qualities and shotcrete erosion must be considered. The values, shapes, and estimating methods of rock load and water pressure are very different with every designers. Estimating methods of rock loads used in the design of NATM tunnel concrete lining are investigated. Structural analyses are done in various load combinations, and the member forces(moment, axial force and shear force) are compared. The adequate load combination of rock load and water pressure is proposed.

• Wind and Structures
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• v.11 no.6
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• pp.441-453
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• 2008

In this study, a partially earth-anchored cable system is studied in order to reduce the dynamic wind response of cable-stayed bridges. The employment of earth-anchored cables changes the dynamic characteristics of cable-stayed bridges under wind loads. In order to estimate the changes in the member forces, the spectral analysis for wind buffeting loads are performed and the peak responses are evaluated using 3-D finite element models of the three-span cable-stayed bridges with the partially earth-anchored cable system and with the self-anchored cable system, respectively. Comparing the results for the two different models, it is found that the earth-anchored cables affect longitudinal and vertical modes of the bridge. The changes of the natural frequencies for the longitudinal modes remarkably decrease the peak bending moment in the pylon and the movements at the expansion joints. The small changes of the natural frequencies for the vertical modes slightly increase bending moments and deflections in the girder. The original effects of the partially earth-anchored cable system are also shown under wind loads; the decrement of girder axial forces and bearing uplifting forces, and the increment of cable forces in the earth-anchored cables.

• Advances in nano research
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• v.3 no.4
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• pp.193-206
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• 2015

The present paper investigate the elastic buckling of chiral double-walled carbon nanotubes (DWCNTs) under axial compression. Using the non-local elasticity theory, Timoshenko beam model has been implemented. According to the governing equations of non-local theory, the analytical solution is derived and the solution for non-local critical buckling loads is obtained. The numerical results show the influence of non-local small-scale coefficient, the vibrational mode number, the chirality of carbon nanotube and aspect ratio of the (DWCNTs) on non-local critical buckling loads of the (DWCNTs). The results indicate the dependence of non-local critical buckling loads on the chirality of single-walled carbon nanotube with increase the non-local small-scale coefficient, the vibrational mode number and aspect ratio of length to diameter.

• Computational Structural Engineering
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• v.3 no.1
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• pp.109-116
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• 1990

Live load data in domestic office buildings have been collected in a systematic manner. Based on surveyed data, equivalent uniformly distributed load intensities, which produce the same load effect as the actual spatially varying, live load, have been obtained for various structural members (such as slab, beam, column, etc. ). Influence surface method has been employed to compute load effects under real live load, including beam moment, slab moment as well as axial force in column. The results have been examined to find probabilistic characteristics and relationship between influence area and load intensity (or coefficient of variation). The results were also compared with other survey results and found to be reasonable. Based on the probabilistic load models obtained, the lifetime extreme values have been analyzed and compared with current design loads. Tentative equations applicable to decide more rational design loads are also suggested as functions of influence area.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.73-80
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• 2013

In this study, a numerical analysis based on CFD methods has been conducted to predict the aerodynamic coefficients and aerodynamic loads of KSLV-II configuration designed at the system design phase. By the effects of exclusion of engine cowls of prior configuration, axial force and normal force decreased and center of pressure was much moved to the nose direction. Also, aerodynamic loads at flight and on the launch pad were predicted for structural load analysis. The computed results will be used for mission analysis and structural analysis at the next design phase.

• Structural Engineering and Mechanics
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• v.45 no.3
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• pp.277-309
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• 2013

Beam-to-column connections behaviour plays an important role in the analysis and design of steel and precast concrete structures. The paper presents a computer-based method for geometrically nonlinear frames with semi-rigid beam-to-column connections. The analytical procedure employs modified stability functions to model the effect of axial force on the stiffness of members. The member modified stiffness matrix, and the modified fixed end forces for various loads were found. The linear and nonlinear analyses were applied for two planar steel structures. The method is readily implemented on a computer using matrix structural analysis techniques and is applicable for the efficient nonlinear analysis of frameworks.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.521-524
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• 1999

Twelve column specimens were tested in compression, six were slab-column specimens and six were isolated column specimens. The slab column specimens were first tested to punching shear failure before the columns of the specimens were loaded axially. The effects of confinement from the surrounding slab on the axial capacity of the columns was investigated. Other parameters investigated were the placement of fiber-reinforced concrete in the slab and the concentration of flexural reinforcement in the column vicinity.