• Title, Summary, Keyword: 이동하중

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Effect of the Combination of Point Loads on the Design Flexural Capacity for Fiber Reinforced Concrete Floor Slab (집중하중 조합에 의한 섬유 보강 콘크리트 바닥슬래브의 설계 휨 내력)

  • Lee, Jong-Han;Cho, Baik-Soon;Kim, Jung-Sik;Cho, Bum-Gu;Ki, Han-Sik
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.4 no.1
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    • pp.47-54
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    • 2016
  • In this study, the flexural capacity of fiber reinforced concrete floor slabs were evaluated using main design loads, racking and moving loads. Based on design standards and guidelines, the magnitude and loaded area of each load were determined, and its relationship was assessed. For the application of a single load, flexural capacity should be evaluated in the edge of a floor slab. In addition, the slab with thickness and concrete strength, greater than 180mm and 35MPa, respectively, sufficiently satisfied flexural capacity with a minimum of equivalent flexural strength ratio. The combination of racking loads required the largest equivalent flexural strength ratio to satisfy the flexural capacity of the floor slab. The combination of racking and moving loads showed equivalent flexural strength ratio smaller than the case of combination of racking loads, but larger than the application of single racking or moving loads. The results of this study indicated that the flexure of fiber reinforced concrete floor slabs should be designed using the combination of design loads.

Effects of Moving Dynamic Vehicle Loads on Flexible Pavement Response (차량의 이동하중과 하중형태가 연성 포장의 거동 특성에 미치는 영향 평가)

  • Jo, Myoung-Hwan;Kim, Nak-Seok;Nam, Young-Ho;Im, Jong-Hyuk
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.1
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    • pp.39-45
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    • 2008
  • The most important elements in flexible pavement design criteria are stress and strain distributions. To obtain reasonable stress and strain distributions in pavements, moving wheel loads must be applied to analyze the pavement responses. In this study, finite element analysis was used to identify the three-dimensional states using the vehicle load into a constant-position / time-variable load (25, 50 and 80km/hr). In an elastic system, the strain is the same in both longitudinal and transverse directions under a single wheel. However, the same is not necessary in a viscoelastic system. Test results showed that the maximum values between transverse and longitudinal strains the bottom of asphalt concrete base layers under 25km/hr were were about 40 percent.

A Study on Sound Radiation From Infinite Beams Under the Action of Moving Harmonic Point Forces (조화집중이동하중을 받는 무한보에서의 음향방사에 관한 연구)

  • 김병삼;태신호;홍동표
    • The Journal of the Acoustical Society of Korea
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    • v.12 no.4
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    • pp.39-46
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    • 1993
  • 조화집중이동하중을 받는 무한보에서의 음향방사에 대한 연구는 선박, 비행기, 타이어 트레드 밴느 등과 같은 계의 설계시 계의 구조물로부터 발생하는 소음에 대한 해결방안을 제시해 준다. 구조물 표면에 발생하는 음향파워는 svktnqusghks방법을 이용하여 보의 전길이에 분포된 음향 인텐시티를 적분하여 구한다. 보의 표면에서 발생하는 음향파원는 미하수, 장력, 감쇠계수, 기초강성계수, 그리고 파수비에 의해서 결정된다. 각 인자에 따른 음향파워에 대한 정성적인 분석을 수행하기 위해 심프슨 적분방법을 이용하여 수치적분을 하였다. 무한보에 작용하는 유체하중에 3다라 진동에너지가 음향에너지로 변환되는 비율이 달라진다. 밀도가 큰 유체는 등가감쇠로 작용하여 보로부터 방사된 음향에너지는 빠르게 감소된다. 하중의 이동에 의하여 도플러이동효과가 발생하여 무한보의 공진부근에서의 음향파워 파크가 분리되고 보의 기초감쇠의 영향으로 음향에너지는 감소된다.

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Problems Double Integration of an Acceleration to Determine Displacement Characteristics of a Structure under Moving Load (이동하중을 받는 보의 변위응답 산정을 위한 가속도신호의 적분상 문제점)

  • 양경택
    • Computational Structural Engineering
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    • v.11 no.4
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    • pp.135-146
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    • 1998
  • 대형 시스템의 건전성 평가를 위한 동적 재하시험에 있어서 변위를 측정하는 것보다 가속도를 측정하는 것이 수월하나 대부분의 공학적 기준은 응력과 비례관계를 지니는 변화를 기준으로 하고 있다. 본 연구에서는 시스템의 재하시험시 측정된 가속도신호를 이용하여 변위응답을 산정하는데 그 목적을 두고 적분을 위한 신호처리시 발생되는 문제점을 정상상태 및 천이영역에 대하여 규명하였다. 기존의 연구에서 고려하지 못하였던 초기조건의 항을 도입함으로써 시간영역의 적분과 주파수영역의 적분결과가 일치함을 해석적으로 입증하였으며 이동하중을 받는 보의 동적거동에 대하여 제시된 타당성을 검증하였다.

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Evaluation of Dynamic Stability for Structural Bar Reinforced Precast and Prestressed Retaining Wall for Moving Train Load (이동열차하중에 대한 강봉으로 보강된 프리캐스트 프리스트레스트 옹벽의 동적 안정성 평가)

  • Lee, Il Wha;Um, Ju Hwan;Lee, Kang Myung;Keum, Chang Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.5
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    • pp.190-198
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    • 2011
  • The precast production has many advantages by fast construction period, labor-saving and high quality. In recent years, the application of the precast product has been increased in the earth retaining wall field. This paper presents the results of the numerical analysis that was carried out to evaluate the dynamic stability of precast and prestressed earth retaining wall under moving train load. The two-dimensional FEM analysis was used to the numerical analyses. The train load to act on trackbed is combined by the real measured roughness phase angle and quasi-static load. The dynamic stability is analysed by the displacement, acceleration and stress under moving train load at each specified location. The results of the analysis show that the precast and prestressed retaining wall has very stable capability for the railway.

A Study on the Bending and Torsional Behaviors of Cable-Stayed Bridges under a Concentrated Moving Load (집중 이동하중을 받는 사장교의 휨 및 비틈 거동에 관한 연구)

  • Chang, Sung Pil;Yhim, Sung Soon;Chu, Seok Beom
    • Journal of The Korean Society of Civil Engineers
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    • v.9 no.3
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    • pp.1-12
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    • 1989
  • The nonlinearity of a cable-stayed bridge results from the large displacement of main girder due to a long span, the catenary action of cables and the flexural stiffness reduced by large axial forces. The dynamic behaviour of a cable-stayed bridge plays an important role in determining its safety. Especially, when the eccentrically moving load is applied to a cable-stayed bridge, the torsional vibration and vertical vibration are coupled and moreover the variation of cable tensions shows important dynamic characteristics. This dissertation presents a theoretical study and a finite element procedure for analysis of a cable-stayed bridge under a eccentrically moving load. Attention is focused on the dynamic behaviours such as dynamic increments of cable tensions and nodal displacements, with the variety of velocities and eccentricities of moving load. It is found that a moving load with eccentricity can have significant effects upon the responses; the torsion of bridge deck and the increments of cable tensions, according to the present results in this study.

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Movements of the Center of Pressure During Stance Phase in Free Level Walking of Normal Adults (정상인의 지면수평자보행에 대한 입각기 압력중심의 이동)

  • 김영호;양길태;문무성;박시복
    • Journal of Biomedical Engineering Research
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    • v.20 no.5
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    • pp.587-592
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    • 1999
  • 압력측정시스템은 입각기동안 동적압력분포를 성공적으로 측정할 수 있으나 하중수용기-중간입각기, 말기입각기-전유각기의 전환기들에 대해서는 운동분석시스템을 사용하지않고는 정확한 정의가 불가능하다. 따라서 저자들은 수평자유보행 시 압력중심의 이동을 이해하기 위해서 정상적인 발을 가진 20-30대 성인남자 78명을 대상으로 동작분석과발바닥 압력측정을 동시에 수행하였다. 결과로 하중반응기-중간입각기 전환시기의 발바닥 압력중심점은 후족부와 중족부의 경계선에서 앞쪽으로 1.9$\pm$1.5frame(32$\pm$24msec)에 위치하였으며 말기입각기-전유각기 전환시기에는 중족골두 최대 압력점의 앞쪽으로 2.3$\pm$2.0 frame(38$\pm$33msec)에 위치하였다. 정상수평보행에 있어서 최초접지 순간 압력중심은 전방으로 빠르게 이동하다가 바로 급속히 감소하여 하중반응기-중간입각기의 전환시기에는 작은 속도로 이동하였다. 압력중심의 이동속도는 그 후 다시 서서히 증가하다가 전체 보행주기의 25% 전후에서 서서히 감소하여 비교적 일정하다가 말기입각기-전유각기의 전환시점에서 다시 급격한 증가를 보였다. 족부질환과 보행특성을 판단하는데 있어서 압력중심의 이동궤적은 매우 유용한 인자가 될 것으로 기대된다. 본 연구를 통해서 압력측정시스템만으로는 정의할 수 없었던 두 전환기인 하중반응기-중간입각기, 말기입각기-전유각기를 결정할 수있게 되었다.

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Estimation of Dynamic Response of Advanced Composite Material Decks for Bridges Application under Various Vehicle Driving Velocities (복합재료 교량 바닥판의 주행속도에 따른 동적응답 평가)

  • 천경식;장석윤
    • Composites Research
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    • v.16 no.6
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    • pp.23-32
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    • 2003
  • Applications of advanced composite material in construction field are tending upwards and development of all composite material bridges is making progress rapidly in home and abroad due to their high strength to weight ratio. This paper formulated the dynamic responses of the laminated composite structures subjected to moving load and analyzed the various dynamic behaviors using the finite element method. The nondimensionalized natural frequencies of a simply supported square-laminated composite plate are considered for verifications. Mode superposition and Newmark direct integration method are applied for moving load analysis. For structural models, dynamic magnification factor calculated for various velocities of the moving load and displacements characteristics of laminated composite structures due to the moving load are investigated theoretically Numerical results are presented to study the effects of lamination scheme, stacking sequence, and fiber angle for laminated composite structures during moving load. The various results on moving load and lamination through numerical analysis will present an important basic data for development and grasp the behavior of all composite material bridges.

Experimental Study on the Dynamic Response of Box Girder Long-Span Bridges under Various Travelling Vehicles (다양한 차량주행에 의한 박스형 장대교량의 동적 응답에 관한 실험적 연구)

  • Lee, Rae-Chul;Lee, Sang-Youl;Yhim, Sung-Soon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.1
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    • pp.129-138
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    • 2004
  • In this study we determine a dynamic analysis of the existing two-span prestressed concrete box girder bridge subjected to moving vehicle loads using the experimental measurements. The moving loads applied in this paper are classified as general travelling, suddenly brake, continuous travelling, reversely travelling and reversely travelling impact loads for increasing velocities. For each travelling load, we search dynamic behaviors and characteristic in various measuring point of box girder section. In addition, the three-dimensional numerical results analyzed by the developed finite element program using flat shell element with six degrees of freedom per a node are compared with the measured experimental data. Dynamic behaviors caused impact loads by suddenly braking, reversely travelling, are bigger than by general travelling in box girder. Three-dimensional numerical results are better than one-dimensional results.

Resonance Phenomenon according to the relationship between Span Length of the Bridge and Effective Beating Interval of High-Speed Train (교량의 지간장과 고속전철하중 유효타격간격 사이의 관계에 따른 공진현상)

  • 김성일;곽종원;장승필
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.2
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    • pp.67-76
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    • 1999
  • Resonance of the bridge can be occurred with the coincidence between a natural frequency of the bridge and a crossing frequency of moving loads which is determined from the speed and effective beating interval of the vehicle. In case of the railway bridge, the effective beating interval of the vehicle is fixed under the passage of specific trains. In the present study, resonance and cancellation of the bridge subjected to moving high-speed train are analyzed with the variations of span length. A steel-concrete composite railway bridge is idealized by the combinations of plate elements and space frame elements. High-speed train is idealized with moving constant forces and a 3-dimensional full modelling. From analyzing dynamic responses of D.M.F of vertical displacement, maximum vertical acceleration of the slab, and end rotation according to the variations of span length of the bridge, design criteria of span length of the bridge which satisfies dynamic safety is discussed.

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