• Journal of Mechanical Science and Technology
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• v.20 no.6
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• pp.748-758
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• 2006

In this paper, we have revisited the estimation of the rotational stiffness of sidewall of radial tire and have suggested a new method for evaluation of the rotational stiffness. Since thicknesses, and volume fractions of the constituents of sidewall are varied depending on radial position, the equivalent shear modulus of the sidewall also depends on radial position. For the estimation of rotational stiffness of sidewall's rubber, we have divided its cross-section into sufficient numbers of small parts and have calculated the equivalent shear modulus of each part of sidewall. Using the shear moduli of divided parts, we have obtained the rotational stiffness by employing in-plane shear deformation theory. This method is expected to be a useful tool in tire design since it relates such basic variables to the global stillness of tire. Applying the calculation method to a radial tire of P205/60R15, we have compared its rotational stiffness with experimental one.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.938-941
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• 2011

This paper deals with the equivalent shear modulus of the egg-box core. There are three approaches to obtain the equivalent shear modulus of core: a finite element analysis, an analytical study, and an empirical method. In this study, an 3-point bending test is used to evaluate the equivalent shear modulus of the Egg-Box core. As a result of the present work, the equivalent shear modulus of egg-box core at room temperature can be obtained. And this result is compared with the result of finite element analysis.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.39-44
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• 2003

It is important to find the shear center of beam with arbitrary cross-section in structures. In this study, it is introduced to determine the shear center that gets the equivalent stiffness matrix representing arbitrary cross section of beam and applies concepts of equivalent energy. This method shows the results of applying on examples that the exact and approximate solution of open and cross section of beam is known. The shear center of composite rotor blade by the experiment and by the suggested method was compared in this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.121-129
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• 2010

In this paper, the characteristics of high damping rubber bearing were studied through various prototype test. The characteristics of HDRB were dependent on displacements, repeated cycles, frequencies, vertical pressure, temperature, the capability of shear deformation and the vertical stiffness. The prototype test showed that the displacement was the most governing factor influencing on characteristics of HDRB. The effective stiffness and equivalent damping of HDRB were decreased with displacement, and increased with frequency. The effective stiffness was decreased with high vertical pressure, while the equivalent damping was increased. In which, the equivalent damping was more dependent on the vertical pressure than the effective stiffness. According to the results of this study, more careful examination is required to design the effective stiffness and equivalent damping ratio considering the dependencies of design displacement and exciting velocity.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.93-98
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• 2002

It is important to determinate the shear center of beam having arbitrary cross-section in structures. In this study, we have introduced the determination of shear center that gets the equivalent stiffness matrix representing arbitrary cross section of beam and applies energy equivalence theory. This method shows the results of applying on examples that we know the exact and approximate solution of open and cross section of beam. This study also compares with the shear center of composite rotor blade got by the experiment and by the suggested method.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.312-316
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• 1995

Flat-plate buildings are commonly modeled as two-dimensional frames to calculate lateral drift, unbalanced moments, and shear at slab-column connections. For gravity loads. the slab-column frames are analyzed using equivalent column approach, while equivalent beam approach is typical for lateral loads. The equivalent beam approach is convenient for computer analysis, but no rational procedure exists for determining the effective width of foor slabs. At present, the determination of the equivalent slab width and its stiffness is a matter of engineering judgement. To account for cracking, overly conservative assumptions are made regarding the stiffness of the slab. A rational approach is therefore needed to realistically estimate the equivalent slab width and its stiffness for unbalanced moment and lateral drift calculations. Based on the test results of 8 interior slab-column connections, an equivalent beam model is proposed in which columns are modeled conventionally as a function of column and slab aspect ratios and the magnitude of the gravity load. the proposed approach is verified with selected experimental results and is founded to be practical and convenient for analyzing flat-plate buildings subjected to gravity and lateral loading.

• Structural Engineering and Mechanics
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• v.55 no.4
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• pp.801-813
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• 2015

Flexural stiffness of bridge spans has become even more important parameter since Eurocode 1 introduced for railway bridges the serviceability limit state of resonance. For simply supported bridge spans it relies, in general, on accurate assessment of span moment of inertia that governs span flexural stiffness. The paper presents three methods of estimation of the equivalent moment of inertia for such spans: experimental, analytical and numerical. Test loading of the twin truss bridge spans and test results are presented. Recorded displacements and the method of least squares are used to find an "experimental" moment of inertia. Then it is computed according to the analytical method that accounts for joint action of truss girders and composite deck as well as limited span shear stiffness provided by diagonal bracing. Finally a 3D model of finite element method is created to assess the moment of inertia. Discussion of results is given. The comparative analysis proves efficiency of the analytical method.

• Steel and Composite Structures
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• v.3 no.5
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• pp.333-348
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• 2003

The behaviour of composite frame - shear wall systems with regard to creep and shrinkage with high beam stiffness has been largely unattended until recently since no procedure has been available. Recently an accurate procedure, termed the Consistent Procedure (CP), has been developed which is applicable for low as well as for high beam stiffness. In this paper, CP is adapted for a class of composite frame - shear wall systems comprising of steel columns and R.C. shear walls. Studies are reported for the composite systems with high as well as low beam stiffness. It is shown that considerable load redistribution occurs between the R.C. shear wall and the steel columns and additional moments occur in beams. The magnitude of the load redistribution and the additional moment in the beams depend on the stiffness of the beams. It is also shown that the effect of creep and shrinkage are greater for the composite frame - shear wall system than for the equivalent R.C. frame - shear wall system.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.39-49
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• 2002

In this paper, the characteristics of RB(rubber bearing) were studied by various prototype tests on RB with low hardness rubber. The characteristics of RB were tested on displacements, repeated cycles, frequencies, vertical pressures, temperature, vertical stiffness and the capability of shear deformation. The prototype test showed that the displacement and vertical pressures were the most governing factors influencing on characteristics of RB. The effective stiffness and equivalent damping of RB showed small increment in high frequency range. After the repeated cyclic test with 50's cycles, the effective stiffness and equivalent damping of RB were almost constant compared with those of the 1st cycles due to low hysteretic damping. The shear modulus of RB was reduced after large deformation, and this value of RB was partly recovered after 40 days. Finally, the shear failure test of RB was conducted, the prototype was failed over 490% of shear strain, and real size RB was failed over 430% of shear strain.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.273-276
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• 2008

Equivalent linear method indirectly reflects a variation of shear modulus(G/Gmax) and damping ratio $(\xi)$ by selects mean value of every response analysis. Existing equivalent linear method does not properly consider variation of shear strain along frequencies and uses mean value. Real dynamic soil behavior is affected by shear stiffness and damping ratio. Modified equivalent linear method is developed to consider variation. Modified equivalent linear method can reflects high strain at low frequency and low strain at high frequency by using an easement curve. This study presents propriety of method by case study.