• Earthquakes and Structures
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• 제5권5호
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• pp.589-605
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• 2013

The effect of dead loads on dynamic responses of a uniform elastic beam subjected to moving loads is examined by means of a governing equation which takes into account initial bending stresses due to dead loads. First, the governing equation of beams which includes the effect of dead loads is briefly presented from the author's paper (1990, 1991, 2010). The effect of dead loads is considered by a strain energy produced by conservative initial stresses caused by the dead loads. Second, the effect of dead loads on dynamical responses produced by moving loads in simply supported beams is confirmed by the results of numerical computations using the Galerkin method and Wilson-${\theta}$ method. It is shown that the dynamical responses by moving loads are decreased remarkably on a heavyweight beam when the effect of dead loads is included. Third, an approximate solution of dynamic deflections including the effect of dead loads for a uniform beam subjected to moving loads is presented in a closed-form for the case without the additional mass due to moving loads. The proposed solution shows a good agreement with results of numerical computations with the Galerkin method and Wilson-${\theta}$ method. Finally it is clarified that the effect of dead loads on elastic uniform beams subjected to moving loads acts on the restraint of the transverse vibration for the both cases without and with the additional mass due to moving loads.

• Structural Engineering and Mechanics
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• 제7권4호
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• pp.361-375
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• 1999

This paper presents an analytic method of examining the out-of-plane vibration of continuous curved beam on periodical supports. The orthogonality of two distinct sets of mode shape functions is derived. The forced vibration of beam due to moving loads is examined. Two types of moving loads, which are concentrated load and uniformly distributed load, are considered. The response characteristics of beam induced by these loads are investigated as well.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2058-2066
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• 1999

The present paper proposes a new dynamic analysis method for multi-span Timoshenko beam structures supported by joints with damping subject to moving loads. An exact dynamic element matrix method is adopted to model Timoshenko beam structures. A generalized modal analysis method is applied to derive response formulae for beam structures subject to moving loads. The proposed method offers an exact and closed form solution. Two numerical examples are provided for validating and illustrating the proposed method. In the first numerical example, a single span beam with multiple moving loads is considered. A dynamic analysis on a multi-span beam under a moving load is considered as the second example, in which the flexibility and damping of supporting joints are taken into account. The numerical study proves that the proposed method is useful for the vibration analysis of multi-span beam-hype structures by moving loads.

• 대한기계학회논문집
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• 제6권4호
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• pp.323-330
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• 1982

The vibration characteristics of continuous span periodically supported beams with moving loads are determined theoretically and experimentally. Moving loads are assumed to travel at constant acceleration with constant magnitude. Analyses by using the Fourier Transform technique are developed to determine the dynamic performance of moving load interacting with multiple and continuous beam. Equation of motion for the moving load is non-dimensionalized. Non-dimensional deflection proflies of continuous beam are presented in detail for the single concentrated moving load with constant acceleration. Experimental moving load and continuous beam models are developed. The maximum deflections at each midpoints 5,7 and 9 span beam are measured and their non-dimensional maximum deflections are presented. The non-dimensional maximum deflection of continuous beam is compared with measured maximum deflection of 9 span beam and found to agree reasonably well. The deflection of continuous beam due to moving load with acceleration is strongly influenced in the resonance region.

• 한국철도학회논문집
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• 제14권1호
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• pp.49-56
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• 2011

이 논문에서는 모형토조 실험으로 하중을 재하하는 방법에 따라 응력과 침하특성을 비교하였으며, 하중재하 방법의 차이를 정량적으로 평가하기 위하여 응력경로와 주응력 방향의 회전영향을 평가하였다. 실험결과 동일 시험조건에서 하중재하 방법에 따라 침하량과 토압이 달라지며, 이동하중의 경우 고정된 지점에서의 정적하중보다 침하량이 약 6배, 반복하중보다 약 2배 이상 크게 발생하였다. 응력경로에서도 고정된 지점에서의 반복하중보다 응력경로의 길이(L)는 2배 이상이 길고 전단변형에 영향을 주는 축차응력도 약 2배 이상 크게 나타났다. 또한, 도상자갈이 있는 궤도에서의 이동하중의 경우 주응력 방향의 회전각이 약 ${\Delta}{\theta}=40^{\circ}$ 최대 응력의 약 60%정도 발생하고 있으며, 주응력 방향의 회전에 영향을 받고 있다는 것을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제6권2호
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• pp.229-243
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• 1998

In this study, a theoretical method to analyze the vibration of a T-type Timoshenko frame is proposed. The effects of axial inertia, rotatory inertia and shear deformation of each branch are considered. The orthogonality of any two distinct sets of mode shape functions is also demonstrated. Vibration of the frame due to moving loads is studied by the method and the response characteristics of the frame are investigated. Furthermore, the effect of column length on the response of the frame is also studied.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.174-181
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• 2003

The groundborne vibration from moving train loads in tunnels could cause damages on structures and make people uneasy. With an aim at developing basis for effective screening measures, this paper attempts to study the characteristics of propagation and attenuation of groundborne vibration from moving train loads in tunnels considering the effect of joints. The wave propagation problem is modeled by a commercial code FLAC and the results are compared to those from using a finite-element-based code DIANA. It is shown that the groundborne vibration is affected significantly by the location and direction of joints.

• Structural Engineering and Mechanics
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• 제13권2호
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• pp.211-230
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• 2002

The objective of this study is to investigate the dynamic behavior of elastic beams subjected to moving loads. Although analytical methods are available, they have limitations with respect to complicated structures. The use of computer technology in recent years is an effective way to solve the problem; thus using the latest technology this study establishes a finite-element solution procedure to investigate dynamic behaviors of a typical elastic beam having a set of constant geometric properties and various span lengths. Both the dead load of the beam and traffic load are applied in which the traffic load is considered a concentrated moving force with various traveling passage speeds on the beam. Dynamic behaviors including deflection, shear, and bending moment due to moving loads are obtained by both analytical and finite element methods; for simple structures, they have an excellent agreement. The numerical results show that based on analytical methods the fundamental mode is good enough to estimate the dynamic deflection along the beam, but is not sufficient to simulate the total response of the shear force or the bending moment. The linear dynamic behavior of the elastic beams subjected to multiple exciting loads can easily be found by linear superposition, and the geometric nonlinear results caused by large deformation and axial force of the beam are always underestimated with only a few exceptions which are indicated. In order to make the results useful, they have been nondimensionalized and presented in graphical form.

• 한국공간구조학회논문집
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• 제11권1호
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• pp.113-120
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• 2011

지붕구조의 개폐가 가능한 체육시설 및 복합시설은 대공간구조물의 장점을 잘 나타내고 있으며 대공간구조물의 전천후 사용이 가능하도록 하였다. 개폐식 지붕구조는 구조형식, 마감재료, 개폐방식에 따라서 매우 다양하며 개폐방식에 따라서 중첩방식, 수평이동방식, 주름접기방식 등으로 구분할 수 있다. 특히 중첩방식이나 수평이동방식에 의한 지붕구조의 움직임은 주행하중, 충격하중, 관성력 및 제동력과 같은 동적하중이 구조물에 가해질 수 있으므로 이에 대한 대공간구조물의 진동해석이 필요할 것으로 사료된다. 지붕구조의 움직임에 의한 주행하중은 이동질량 또는 이동하중으로 적용할 수 있으나 비교적 움직임이 느린 개폐식 지붕구조에 의한 동적하중은 아동하중으로 적용하는 것이 타당하다. 따라서 본 논문에서는 지붕구조의 개폐로 야기되는 이동하중에 대한 새로운 적용방법을 제안하고 이를 이용하여 개폐식 지붕의 개폐속도에 따른 대공간구조물의 진동해석을 수행하였다. 본 논문에서 제안된 등가 이동하중은 지붕구조 개폐에 의한 대공간구조물의 진동해석에 있어서 매우 용이하게 활용할 수 있다.

• Interaction and multiscale mechanics
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• 제3권1호
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• pp.95-110
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• 2010

In recent years, study of the static response of pavements to moving vehicle and aircraft loads has received significant attention because of its relevance to the design of pavements and airport runways. The static response of beams resting on an elastic foundation and subjected to moving loads was studied by several researchers in the past. However, most of these studies were limited to steady-state analytical solutions for infinitely long beams resting on Winkler-type elastic foundations. Although the modelling of subgrade as a continuum is more accurate, such an approach can hardly be incorporated in analysis due to its complexity. In contrast, the two-parameter foundation model provides a better way for simulating the underlying soil medium and is conceptually more appealing than the one-parameter (Winkler) foundation model. The finite element method is one of the most suitable mathematical tools for analysing rigid pavements under moving loads. This paper presents an improved solution algorithm based on the finite element method for the static analysis of rigid pavements under moving vehicular or aircraft loads. The concrete pavement is discretized by finite and infinite beam elements, with the latter for modelling the infinity boundary conditions. The underlying soil medium is modelled by the Pasternak model allowing the shear interaction to exist between the spring elements. This can be accomplished by connecting the spring elements to a layer of incompressible vertical elements that can deform in transverse shear only. The deformations and forces maintaining equilibrium in the shear layer are considered by assuming the shear layer to be isotropic. A parametric study is conducted to investigate the effect of the position of moving loads on the response of pavement.