• Title, Summary, Keyword: moving loads

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Effects of dead loads on dynamic analyses of beams subject to moving loads

  • Takabatake, Hideo
    • Earthquakes and Structures
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    • v.5 no.5
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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.

Out-of-plane vibration of multi-span curved beam due to moving loads

  • Wang, Rong-Tyai;Sang, Yiu-Lo
    • Structural Engineering and Mechanics
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    • v.7 no.4
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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.

Vibration Analysis of Multi-Span Timoshenko Beams Due to Moving Loads (여러 스팬을 갖는 티모센코 보 구조물의 이동하중에 의한 진동 해석)

  • Hong, Seong-Uk;Kim, Jong-Uk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.23 no.11
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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.

A Pilot Study of Moving Loads Simulation Techniques (이동하중 재현 시험 기법에 대한 선행 연구)

  • Kim, Hyun-Min;KIm, Sung-Il
    • Proceedings of the KSR Conference
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    • pp.1492-1499
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    • 2010
  • This paper is intended as an development of moving load simulation techniques. The concern with dynamic problem of railway bridge caused by the moving train loads has been growing. Over the past few years, several studies have been made on dynamic stability of railway bridge analytically. But very few attempts have been made at experimental research. From the dynamic stability view point, the moving train loads simulation test is revolutionary idea. It can be replace restrictive filed test with new laboratory test. This study investigates minimum specifications of hardware and basic parameters. it is used 39m girder and 4 actuators for experimental verification.

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Vibration Characteristics of Continuous Beams Due to the Moving Loads with Constant Accelerations (一定加速度 의 移動荷重 이 作용하는 連續보 의 振動特性)

  • 김찬묵;김광식
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.6 no.4
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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.

A Comparative of Ground Stress with Difference of the Fixed Point Loading and Moving Wheel Loading (모형실험을 통한 고정 및 이동하중 재하 방법에 따른 노반 변형거동 비교)

  • Choi, Chan-Yong;Shin, Eun-Chul;Eum, Ki-Young;Shin, Min-Ho
    • Journal of the Korean Society for Railway
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    • v.14 no.1
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    • pp.49-56
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    • 2011
  • In this paper, it was compared the characteristics of the stress and settlement that occur from a track on the ground using a model test and has quantitatively analyzed the difference based on stress path and effect of the rotation of principal stress. Under identical roadbed conditions, the settlement generated by moving wheel loads were found to be 6 times and 3 times larger than that from static loads and cyclic loads, respectively. The deviator stress affecting shear deformation and the length of stress path generated by moving loads were twofold or greater increase than those by static loads. Furthermore, the stress path generated by moving loads was approached more closely to Mohr-Coulomb failure criteria compared to that by static loads. Also, it was found that ballasted track was occurred about 60% of maximum stress at $40^{\circ}$ of the rotation angle of principal stress and was affected with rotation of principal stress with moving wheel loading condition.

Vibration of T-type Timoshenko frames subjected to moving loads

  • Wang, Rong-Tyai;Lin, Jin-Sheng
    • Structural Engineering and Mechanics
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    • v.6 no.2
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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.

Finite element dynamic analysis of laminated composite beams under moving loads

  • Kahya, Volkan
    • Structural Engineering and Mechanics
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    • v.42 no.5
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    • pp.729-745
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    • 2012
  • This study presents dynamic analysis of laminated beams traversed by moving loads using a multilayered beam element based on the first-order shear deformation theory. The present element consists of N layers with different thickness and material property, and has (3N + 7) degrees of freedom corresponding three axial, four transversal, and 3N rotational displacements. Delamination and interfacial slip are not allowed. Comparisons with analytical and/or numerical results available in literature for some illustrative examples are made. Numerical results for natural frequencies, deflections and stresses of laminated beams are given to explain the effect of load speed, lamina layup, and boundary conditions.

Dynamic response of non-uniform Timoshenko beams made of axially FGM subjected to multiple moving point loads

  • Gan, Buntara S.;Trinh, Thanh-Huong;Le, Thi-Ha;Nguyen, Dinh-Kien
    • Structural Engineering and Mechanics
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    • v.53 no.5
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    • pp.981-995
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    • 2015
  • This paper presents a finite element procedure for dynamic analysis of non-uniform Timoshenko beams made of axially Functionally Graded Material (FGM) under multiple moving point loads. The material properties are assumed to vary continuously in the longitudinal direction according to a predefined power law equation. A beam element, taking the effects of shear deformation and cross-sectional variation into account, is formulated by using exact polynomials derived from the governing differential equations of a uniform homogenous Timoshenko beam element. The dynamic responses of the beams are computed by using the implicit Newmark method. The numerical results show that the dynamic characteristics of the beams are greatly influenced by the number of moving point loads. The effects of the distance between the loads, material non-homogeneity, section profiles as well as aspect ratio on the dynamic responses of the beams are also investigated in detail and highlighted.

Vibration Analysis of Space Structure with Retractable Roof (개폐식 지붕구조의 움직임에 대한 공간구조물의 진동해석)

  • Kim, Gee-Cheol;Kang, Joo-Won;Kim, Hyun-Su
    • Journal of Korean Association for Spatial Structures
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    • v.11 no.1
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    • pp.113-120
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    • 2011
  • Retractable roof system is one of the special feature in stadium or complex structure. And this retractable roof system makes possible to use spacial structure all-weather. This retractable roof system is able to classified into overlapping, parallel movement and folding system. Moving load, impact load, inertial or braking loads, these dynamic loads induced by movements of retractable roof system. So it is necessary to analysis of spacial structures are subjected to these dynamic loads. Dynamic loads that are induced by the retractable roof movements can be applied to moving mass method or moving force method. But, moving force method is appropriate because the retractable roof movements is slow relatively. In this paper, new application method of moving forces induced by the retractable roof movements is proposed. And vibration analysis of spacial structures are executed by using the proposed method. This proposed equivalent moving force can be easily applied to spacial structure that is subjected to dynamic loads induced by movement of the retractable roof system.