• Title/Summary/Keyword: 낮은 아치

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In-Plane Buckling Behavior of Fixed Shallow Parabolic Arches (고정지점을 갖는 낮은 포물선 아치의 면내 좌굴거동)

  • Moon, Jiho;Yoon, Ki-Yong;Lee, Hak-Eun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1A
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    • pp.79-87
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    • 2008
  • This paper investigates the in-plane stability of fixed shallow arches. The shape of the arches is parabolic and the uniformly distributed load is used in the study. The nonlinear governing equilibrium equation of the general arch is adopted to derive the incremental form of the load-displacement relationship and the buckling load of the fixed shallow arches. From the results, it is found that buckling modes (symmetric or asymmetric) of the arches are closely related to the dimensionless rise H, which is the function of slenderness ratio and the rise to span ratio of such arches. Moreover, the threshold of different buckling modes and buckling load for fixed shallow arches are proposed. A series of finite element analysis are conducted and then compared with proposed ones. From the comparative study, the proposed formula provides the good prediction of the buckling load of fixed shallow arches.

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Lowest Symmetrical and Antisymmetrical Natural Frequencies of Shallow Arches on Two-Parameter Elastic Foundations (두 개의 매개변수로 표현되는 탄성지반 위에 놓인 낮은 아치의 최저차 대칭 및 역대칭 고유진동수)

  • 오상진;서종원;이병구
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.2
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    • pp.367-377
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    • 2002
  • This paper deals with the free vibrations of shallow arches resting on elastic foundations. Foundations we assumed to follow the hypothesis proposed by Pasternak. The governing differential equation is derived for the in-plane free vibration of linearly elastic arches of uniform stiffness and constant mass per unit length. Two arch shapes with hinged-hinged and clamped-clamped end constraints we considered in analysis. The frequency equations (lowest symmetrical and antisymmetrical frequency equations) we obtained by Galerkin's method. The effects of arch rise, Winkler foundation parameter and shear foundation parameter on the lowest two natural frequencies are investigated. The effect of initial arch shapes on frequencies is also studied.

Determination of the Critical Buckling Loads of Shallow Arches Using Nonlinear Analysis of Motion (비선형 운동해석에 의한 낮은 아치의 동적 임계좌굴하중의 결정)

  • Kim, Yun Tae;Huh, Taik Nyung;Kim, Moon Kyum;Hwang, Hak Joo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.12 no.2
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    • pp.43-54
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    • 1992
  • For shallow arches with large dynamic loading, linear analysis is no longer considered as practical and accurate. In this study, a method is presented for the dynamic analysis of shallow arches in which geometric nonlinearity must be considered. A program is developed for the analysis of the nonlinear dynamic behavior and for evaluation of critical buckling loads of shallow arches. Geometric nonlinearity is modeled using Lagrangian description of the motion. The finite element analysis procedure is used to solve the dynamic equation of motion and Newmark method is adopted in the approximation of time integration. A shallow arch subject to radial step loads is analyzed. The results are compared with those from other researches to verify the developed program. The behavior of arches is analyzed using the non-dimensional time, load, and shape parameters. It is shown that geometric nonlinearity should be considered in the analysis of shallow arches and probability of buckling failure is getting higher as arches are getting shallower. It is confirmed that arches with the same shape parameter have the same deflection ratio at the same time parameter when arches are loaded with the same parametric load. In addition, it is proved that buckling of arches with the same shape parameter occurs at the same load parameter. Circular arches, which are under a single or uniform normal load, are analyzed for comparison. A parabolic arch with radial step load is also analyzed. It is verified that the developed program is applicable for those problems.

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A Geometrically Nonlinear Dynamic Analysis of Shallow Circular Arches Using Total Lagrangian Formulation (Total Lagrangian 문제형성에 의한 낮은 원호아치의 동적 비선형거동 해석)

  • Kim, Yun Tae;Kim, Moon Kyum;Hwang, Hak Joo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.10 no.2
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    • pp.39-48
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    • 1990
  • For shallow circular arches with large dynamic loading, use of linear analysis is no longer considered as practical and accurate. In this study, a method is presented for the dynamic analysis of the shallow circular arches in which geometric nonlinearity is dominant. A program is developed for analysis of the nonlinear dynamic behavior and for evaluation of the critical buckling loads of the shallow circular arches. Geometric nonlinearity is modeled using Lagrangian description of the motion and finite element analysis procedure is used to solve the dynamic equations of motion in which Newmark method is adopted as a time marching scheme. A shallow circular arch subject to radial step load is analyzed and the results are compared with those from other researches to verify the developed program. The critical buckling loads of shallow arches are evaluated using the non-dimensional parameter. Also, the results are compared with those from linear analysis.

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Lowest Symmetrical and Antisymmetrical Natural Frequency Equations of Shallow Arches on Elastic Foundations (탄성지반 위에 놓인 낮은 아치의 최저차 대칭 및 역대칭 고유진동수 방정식(구조 및 재료 \circled1))

  • 이병구;박광규;오상진;서종원
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.213-218
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    • 2000
  • This paper deals with the free vibrations of shallow arches resting on elastic foundations. Foundations are assumed to follow the hypothesis proposed by Pasternak. The governing differential equation is derived for the in-plane free vibration of linearly elastic arches of uniform stiffness and constant mass per unit length. Sinusoidal arches with hinged-hinged and clamped-clamped end constraints are considered in analysis. The frequency equations (lowest symmetical and antisymmetrical natural frequency equations) are obtained by Galerkin's method. The effects of arch rise, Winkler foundation parameter and shear foundation parameter on the lowest two natural frequencies are investigated.

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Approximate Solution for In-Plane Elastic Buckling of Shallow Parabolic Arches (낮은 포물선 아치의 탄성 면내좌굴에 관한 근사식)

  • Moon, Ji Ho;Yoon, Ki Yong;Yi, Jong Won;Lee, Hak Eun
    • Journal of Korean Society of Steel Construction
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    • v.18 no.4
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    • pp.427-436
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    • 2006
  • The classical buckling theory assumes that prebuckling behavior is linear and that the effect of prebuckling deformations on buckling can be ignored. However, when the rise to span ratio decreases, prebuckling deformation cannot be ignored and the symetrical buckling strength can be smaler than the asymetrical buckling strength. Finally, arches can fail due to snap-through buckling. This paper investigates the non-linear behavior and strength of pin-ended parabolic shallow arches using the non-linear governing differential equation of shallow arches. These results were compared with the solution for the symmetrical buckling load of pin-ended parabolic shallow arches was suggested.

A Study on Buckling Behavior of Shallow Circular Arches (낮은 원호아치의 좌굴거동에 대한 연구)

  • 김연태;허택녕;오순택
    • Journal of the Earthquake Engineering Society of Korea
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    • v.2 no.2
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    • pp.87-94
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    • 1998
  • Behavioral characteristics of shallow circular arches with dynamic loading and different end conditions are analysed. Geometric nonlinearity is modelled using Lagrangian description of the motion. The finite element analysis procedure is used to solve the dynamic equation of motion, and the Newmark method is adopted in the approximation of time integration. The behavior of arches is analysed using the buckling criterion and non-dimensional time, load and shape parameters which Humphreys suggested. But a new deflection-ratio formula including the effect of horizontal displacement plus vertical displacement is presented to apply for the non-symmetric buckling problems. Through the model analysis, it's confirmed that fix-ended arches have higher buckling stability than hinge-ended arches, and arches with the same shape parameter have the same deflection ratio at the same time parameter when loaded with the same parametric load.

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Evaluation of Minimum Depth Criterion and Reinforcement Effect of the Soil Cover in a Long-span Soil-steel Bridge (장지간 지중강판구조물의 최소토피고 평가 및 토피지반 보강에 대한 수치해석)

  • 이종구;조성민;정현식;김명모
    • Journal of the Korean Geotechnical Society
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    • v.20 no.5
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    • pp.67-78
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    • 2004
  • Soil-steel bridges are made of flexible corrugated steel plates buried in the well-compacted granular soil. One kind of possible collapses of these structures could be initiated by shear or tension failure in the soil cover subjected to vehicle loads. Current design codes provide the requirements for the minimum depth of the soil cover to avoid problems associated with soil cover failures. However, these requirements were developed for short span (less than 7.7 m) structures which are made of unstiffened plates of standard corrugation (150$\times$50 m). Numerical analyses were carried out to investigate the behavior of long span soil steel bridges according to thickness of the soil cover. The span of structures were up to 20 m and deep corrugated plates (381$\times$140 m) were used. The analysis showed that the minimum cover depth of 1.5 m could be sufficient to prevent the soil cover failure in the structures with a span exceeding 10 m. Additional analyses were performed to verify the reinforcement effect of the concrete relieving slab which can be a special feature to reduce the live-load effects. Analyses revealed that the bending moment of the conduit wall with a relieving slab was less than 20% of that without a relieving slab in a case of shallow soil cover conditions.