• Title/Summary/Keyword: 등가탄성해석방법

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Estimation on Elastic Properties of SiC Ceramic Honeycomb Substrate (SiC 세라믹 하니컴 담체의 탄성 물성치 평가)

  • Cho, Seok-Swoo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.12
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    • pp.6106-6113
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    • 2013
  • Automotive three-way catalyst substrate has a cordierite ceramic honeycomb structure. The substrate in the high engine speed range doesn't satisfy the design fatigue life due to the low mechanical properties of cordierite ceramic. SiC ceramic has higher mechanical properties than cordierite ceramic. If the automotive three-way catalyst substrate is made from the SiC ceramic honeycomb structure, the substrate can be prevented from premature failure. In this study, the mechanical properties of SiC ceramic honeycomb substrate were estimated by FEA. The FEA results indicated that the MOR and elastic modulus for the SiC ceramic honeycomb substrate was much higher than those for the cordierite ceramic honeycomb substrate.

A Study of the Modification Factor(B) in the AISC Specification for Elastic Buckling of Web-Tapered Beams (웨브 변단면보의 탄성좌굴에 대한 AISC 기준의 수정계수(B)에 관한 연구)

  • Ryu, Hyo-Jin;Lim, Nam-Hyoung
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.2
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    • pp.45-49
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    • 2008
  • This paper investigated the accuracy of the current design formulae for the elastic buckling strength of web-tapered I-beams in AISC-LRFD specification. The basic concept is to replace a tapered beam by an equivalent prismatic beam with a different length, but with a cross section identical to that of the smaller end of the tapered beam. The modification factor, B, is used to account for the stress gradient within the unbraced length and the lateral restraining effects offered by the adjacent segments. The modification factor(B) suggested in AISC-LRFD specification was compared with the finite element method(FEM) results. This paper presented a redefined method to calculate the modification factor(B).

Evaluation of the Inelastic Seismic Response of Curved Bridges by Capacity Spectrum Method using Equivalent Damping (등가감쇠비를 이용한 역량스펙트럼법에 의한 곡선교의 비탄성지진응답 평가)

  • Joe, Yang-Hee;Cho, Sung-Gook;Ma, Jeong-Suck
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.1
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    • pp.17-26
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    • 2009
  • The capacity spectrum method (CSM), which is known to be an approximate technique for assessing the seismic capacity of an existing structure, was originally proposed for simple building structures that could be modeled as single-degree-of-freedom (SDOF) systems. More recently, however, CSM has increasingly been adopted for assessing most bridge structures, as it has many practical advantages. Some studies on this topic are now being performed, and a few results of these have been presented as ground-breaking research. However, studies have until now been limited to symmetrical straight bridges only. This study evaluates the practical applicability of CSM to the evaluation of irregular curved bridges. For this purpose, the seismic capacities of 3-span prestressed concrete bridges with different subtended angles subjected to some recorded earthquakes are compared with a more refined approach based on nonlinear time history analysis. The results of the study show that when used for curved bridges, CSM induces higher inelastic displacement responses than the actual values, and that the gap between the two becomes larger as the subtended angle increases.

Material Nonlinear Analysis of the RC Shells Considering Tension Stiffening Effects (인장강성 효과를 고려한 RC 쉘의 재료비선형 해석)

  • Jin, Chi Sub;Eom, Jang Sub
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.13 no.5
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    • pp.99-107
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    • 1993
  • In this study, material nonlinear finite element program is developed to analyze reinforced concrete shell of arbitrary geometry considering tension stiffening effects. This study is capable of tracing the load-deformation response and crack propagation, as well as determining the internal concrete and steel stresses through the elastic, inelastic and ultimate ranges in one continuous computer analysis. The cracked shear retention factor is introduced to estimate the effective shear modulus including aggregate interlock and dowel action. The concrete is assumed to be brittle in tension and elasto-plastic in compression. The Drucker-Prager yield criterion and the associated flow rule are adopted to govern the plastic behavior of the concrete. The reinforcing bars are considered as a steel layer of equivalent thickness. A layered isoparametric flat finite element considering the coupling effect between the in-plane and the bending action was developed. Mindlin plate theory taking account of transverse shear deformation was used. An incremental tangential stiffness method is used to obtain a numerical solution. Numerical examples about reinforced concrete shell are presented. Validity of this method is studied by comparing with the experimential results of Hedgren and the numerical analysis of Lin.

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Performance Based Design of Friction Dampers for Seismically Excited Structures (지진하중을 받는 구조물의 성능에 기초한 마찰감쇠기 설계)

  • 민경원;김형섭
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.6
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    • pp.17-24
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    • 2003
  • The main objective of this paper is to evaluate the control performance of a coulomb friction damper(CFD) for controlling the inelastic behavior of seismically excited structures, The seismic performances of various buildings are evaluated using capacity spectrum method(CSM), and the additional dampings are calculated If the evaluated performance levels of the buildings are below the target level. Maximum friction force of the CFD to achieve additional damping is provided using the concept of equivalent viscous damping, Numerical simulations for single degree of freedom(SDOF) systems with various structural periods and post yield stiffness ratios demonstrate the effectiveness of the proposed procedure.

Seismic Damage Analysis for Element-Level and System-Level of Steel Structures (강구조물의 구조요소 및 구조계에 대한 지진손상도 해석)

  • 송종걸;윤정방;이동근
    • Journal of the Earthquake Engineering Society of Korea
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    • v.2 no.1
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    • pp.95-111
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    • 1998
  • In this study, the concepts and procedures of the seismic damage analysis methods are examined for both the element-level and the system-level. The seismic damage analysis at the element-level is performed for several example structures using existing method for structural elements or single-degree-of-freedom (SDOF) systems such as the Park and Ang method. In order to analyze seismic damage at the system-level, two types of procedures are used. In the first type of procedure, the system-level seismic responses can be estimated by using the system representative response method(SRRM), or the equivalent SDOF system response method (ESDOF-SRM). Then, the system-level seismic damage is analyzed from the system-level seismic responses using existing method for structural elements or SDOF systems. IN the second type of procedure, the system-level seismic damages are analyzed using the element damage combination method (EDCM) combing the element-level damage indices determined by existing method. To compare tendency of the seismic damage analysis using each methods, example analysis is accomplished for several cases of different structures and different earthquake excitation.

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Sound absorption of micro-perforated elastic plates in a cylindrical impedance tube (원통형 임피던스 튜브 내 미세천공 탄성 판의 흡음)

  • Kim, Hyun-Sil;Kim, Bong-Ki;Kim, Sang-Ryul;Lee, Seong-Hyun;Ma, Pyung-Sik
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.4
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    • pp.181-187
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    • 2018
  • In this paper, sound absorption of micro-perforated elastic plates installed in an impedance tube of a circular cross-section is discussed using an analytic method. Vibration of the plates and sound pressure fields inside the duct are expressed in terms of an infinite series of modal functions, where modal functions in the radial direction is given in terms of the Bessel functions. Under the plane wave assumption, a low frequency approximation is derived by including the first few plate modes, and the sound absorption coefficient is given in terms of an equivalent impedance of a single surface. The sound absorption coefficient using the proposed formula is in excellent agreement with the result by the FEM (Finite Element Method), and shows dips and peaks at the natural frequencies of the plate. When the perforation ratio is very small, the sound absorption coefficient is dominated by the vibration effect. However, when the perforation ratio reaches a certain value, the sound absorption is mainly governed by the rigid MPP (Micro-Perforated Plate), while the vibration effect becomes very small.

Linear and Nonlinear Analysis of Initially Stressed Elastic Solid (초기응력이 있는 탄성체의 선형 및 비선형해석 -플레이트 스트립을 중심으로)

  • 권영두;최진민
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.4
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    • pp.642-651
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    • 1988
  • The present paper develops finite element procedures to calculate displacements, strains and stresses in initially stressed elastic solids subjected to static or time-dependent loading conditions. As a point of departure, we employ Hamilton's principle to obtain nonlinear equations of motion characterizing the displacement in a solid. The equations of motion reduce to linear equations of motion if incremental stresses are assumed to be infinitesimal. In the case of linear problem, finite element solutions are obtained by Newmark's direct integration method and by modal analysis. An analytic solution is referred to compare with the linear finite element solution. In the case of nonlinear problem, finite element solutions are obtained by Newton-Raphson iteration method and compared with the linear solution. Finally, the effect of the order of Gauss-Legendre numerical integration on the nonlinear finite element solution, has been investigated.

A Theoretical and Numerical Study on the Effects of Prereinforcement of Tunnel Face (터널막장 선행보강 효과에 관한 이론적.수치해석적 연구)

  • 김광진;문현구
    • Tunnel and Underground Space
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    • v.11 no.4
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    • pp.328-338
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    • 2001
  • Horizontal tunnel face reinforcement using Fiber Glass Tube(FGT) or steel pipe and pipe roofing techniques are frequently used when the stability of newly excavated tunnel is not guaranteed. However, the mechanical behavior of tunnels using these techniques has not been fully understood so far. Therefore, engineering rule of thumb is commonly applied during designing procedure, and it is difficult to adopt these techniques rationally. In this study, the application of a simplified numerical analysis method based on composite mechanics is verified. The mean field theory and the strain energy theory are used to obtain the equivalence elastic moduli of reinforced soil and rock. Furthermore, a parametric study on the deformational behavior of tunnel face is performed for various patterns of prereinforcement.

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A Study on the Evaluation of Design Moments of R/C Slab by the Finite Element Method (유한요소법(有限要素法)을 이용한 철근(鐵筋)콘크리트 슬래브의 설계(設計)모멘트 산정에 관한 소고(小考))

  • Lee, Sung Woo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.8 no.3
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    • pp.21-29
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    • 1988
  • Evaluation of accurate design moments in two directions is a primary concern in designing R/C Slab. For this purpose, the use of finite element method utilizing isoparametric plate element is proposed. An example of the simply supported slab shows that the results agree well wth those from elastic plate theory throughout the span. The finite element solutions are also compared with those from equivalent frame method in a flat plate example. It is indicated that the distribution of total moment through the width of design strip using the ACI coefficients is unreasonable. In contrary to this, for the same strip model, the finite element method gives accurate moments in two directions. The proposed method can be applied to any geometric configuration of the slab system, thus the approach is considered to be much advantageous and improved one compared with existing methods.

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