• Title, Summary, Keyword: 이동하중

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Dynamic Analysis of a Rigid Body Traveling on the Rotating Shaft (회전축을 따라 이동하는 강체의 동해석)

  • Park, Yong-Suk;Hong, Sung-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.2
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    • pp.435-442
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    • 2010
  • The analysis of rigid body traveling along the rotating Timoshenko shaft has been a topic of interest. The problem arose from the observations that as a structure is subjected to moving loads, dynamic deflection as well as stresses can be significantly higher than those for static loads. The establishment of analytical method for the development and maintenance of performance is required in the fields of the machining operations and the position control using ball screw. The equations of motion for the rotating shaft subjected to the two moving forces are derived by using Hamilton's principle. Influence of system parameters such as the speed ratio, the mass ratio and the Rayleigh coefficient is discussed on the response of the moving system.

A Nonlinear Analysis of Cable Stayed Bridge including Sway Vibrational Effects using Multiple Cable Elements (다수 케이블요소를 사용한 사장교의 횡방향진동을 포함한 비선형 해석)

  • Seong, Ik-Hyun;Yoon, Ki-Yong
    • Journal of Korean Society of Steel Construction
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    • v.12 no.6
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    • pp.661-670
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    • 2000
  • To investigate the characteristics of the dynamic response of long-span cable-stayed bridges due to various dynamic loadings likes moving traffic loads, two different 3-D cable-stayed bridge models are considered in this study. Two models are exactly the same in structural configurations but different in finite element discretization. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. Futhermore case of asymmetric traffic loading clustered in one direction are also considered to study the torsional response of the bridge. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.

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Dynamic Analysis of Structures under Moving Loads in Time and Frequency Domain (이동하중을 받는 구조물에 대한 시간영역과 주파수영역에서의 동적해석)

  • Kong, Min Sik;Yhim, Sung Soon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.3
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    • pp.87-94
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    • 2007
  • A structural dynamic analysis can be divided into a time domain analysis and a frequency domain analysis. The time domain analysis makes use of a direct integration method or a mode superposition method and the frequency domain analysis applies a DFT method. Generally the DFT method is more effective method in case of calculating response of periodic excitation. But in case of transient excitation exact solution can not be acquired. So, by modifying the response or increasing the period accuracy of solution can be enhanced. Accordingly this study analyzed dynamic responses of structures under aperiodic moving load in time domain and frequence domain. Consequently it is concluded that exact solution would be get enough using DFT method by increasing the duration of free vibration or modifying the dynamic response.

Evaluation of Cable Impact Factor by Moving Vehicle Load Analysis in Steel Composite Cable-Stayed Bridges (차량 이동하중 해석에 의한 강합성 사장교 케이블의 충격계수 평가)

  • Park, Yong-Myung;Park, Jae-Bong;Kim, Dong-Hyun;Choi, Byung-Ho
    • Journal of Korean Society of Steel Construction
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    • v.23 no.2
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    • pp.199-210
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    • 2011
  • The cables in cable-stayed bridges are under high stress and are very sensitive to vibration due to their small section areas compared with other members. Therefore, it is reasonable to evaluate the cable impact factor by taking into account the dynamic effect due to moving-vehicle motion. In this study, the cable impact factors were evaluated via moving-vehicle-load analysis, considering the design parameters, i.e., vehicle weight, cable model, road surface roughness, vehicle speed, longitudinal distance between vehicles. For this purpose, two steel composite cable-stayed bridges with 230- and 540-m main spans were selected. The results of the analysis were then compared with those of the influence line method that is currently being used in design practice. The road surface roughness was randomly generated based on ISO 8608, and the convergence of impact factors according to the number of generated road surfaces was evaluated to improve the reliability of the results. A9-d.o.f. tractor-trailer vehicle was used, and the vehicle motion was derived from Lagrange's equation. 3D finite element models for the selected cable-stayed bridges were constructed with truss elements having equivalent moduli for the cables, and with beam elements for the girders and the pylons. The direct integration method was used for the analysis of the bridge-vehicle interaction, and the analysis was conducted iteratively until the displacement error rate of the bridge was within the specified tolerance. It was acknowledged that the influence line method, which cannot consider the dynamic effect due to moving-vehicle motion, could underestimate the impact factors of the end-cables at the side spans, unlike moving-vehicle-load analysis.

Theoretical and Experimental Study on the, Dynamic Behavior of Continuous Bridge having Irregular Surface under-Moving Load (불규칙한 노면(路面)을 주행하는 이동하중에 의한 연속교의 동적거동에 관한 이론 및 실험적 연구)

  • Chang, Sung Pil;Yhim, Sung Soon;Jo, Sir Kyung
    • Journal of The Korean Society of Civil Engineers
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    • v.9 no.3
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    • pp.21-30
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    • 1989
  • In this study, the dynamic behavior of a continuous bridge under moving load is studied considering roughness of the road surface. Vehicle model includes the spring effects of axes, and due to these effects, equations of motions for the vehicle and bridge are derived in coupled form. And then iteration method is used to solve the equations. In experimental study a bridge model is constructed considering the similarity rule in order that the model exhibits dynamic behavior similar to that of prototype. Three types of roughness such as uneven random roughness, uplift on the approach and piece-wise constant roughness are used to describe road roughness. Through the numerical analysis and experiments, the effects of surface roughness, sprung mass, and velocity on the dynamic behavior of the bridge are examined.

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Theoretical Analysis on the Array Microphone Measurement for Noise from Rails (배열 마이크로폰을 이용한 레일 방사 소음 측정에 관한 이론 해석)

  • Ryue, Jungsoo;Jang, Seungho;Kwon, Hyu-Sang
    • The Journal of the Acoustical Society of Korea
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    • v.33 no.4
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    • pp.238-247
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    • 2014
  • In this paper, rail vibration and its sound radiation are investigated, then the rail noise measurement by using microphone array is explored theoretically. A concrete slab track for domestic high speed trains is modeled as a Timoshenko beam on elastic support, regarding the moving of the excitation force on the rail. From the radiation characteristics of rail noise generated by a line source, the effect of moving load on sound radiation is obtained. Also it is found that the beam angle of the microphone array is a prominent factor to measure the rail noise level reliably because the rail noise propagates as a plane wave. In this investigation, a proper beam angle for the rail noise measurement by microphone array is suggested.

Moving Load Analysis of Bridge Structures Using Experimental Modal Data (실험적 모우드 계수를 이용한 교량의 주행하중 해석)

  • 이형진
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.3
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    • pp.409-420
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    • 2002
  • This paper proposed a technique of structural re-analysis for the evaluation of dynamic responses of bridge structure under moving loads using experimental modal results. For successful structural re-analysis, it is required to have accurate estimation techniques of the modal characteristics of bridge structures. The natural frequencies and mode shapes were identified by direct fourier analysis techniques and damping ratios by the random decrement method, respectively. An interpolation method was also proposed for the extension of mode shape measured on limited DOFs. Second, the structural reanalysis was performed using moving mass model and identified modal parameters. The results from the reanalysis show that the proposed technique is very reasonable to evaluate the actual behavior of bridge structures under moving loads.

연계해석 시 해저터널의 이완하중고 산정을 위한 수치 모델링 비교 연구

  • Yu, Gwang-Ho;Lee, Dong-Hun
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • pp.137-146
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    • 2007
  • 해저 지하 구조물을 시공할 경우는 높은 수압 및 침투압 등의 영향이 무시될 수 없으므로 지하저장 공동의 정확한 거동평가를 위해서는 수리-역학적 해석이 수행되어야만 한다. 또한, 실무에서는 암반이완하중을 고려하여 터널의 콘크리트 라이닝을 설계하며, 이를 위해 이완하중고를 터널 주변의 국부안전율 분포를 이용하여 수치해석에 의해 산정하는 방법이 제안된바 있다. 따라서 본 연구에서는 해저터널을 대상으로 수리-역학적 연계해석 시 국부안전율을 이용한 이완하중고 산정 기법의 타당성을 살펴보았다. 이를 위해 3등급 암반을 대상으로 숏크리트 수리특성을 이용한 유도배수방법과 집수정의 펌핑을 이용한 유도배수방법을 이용하여 이완하중고를 산정하고 적용성을 비교하였다. 연구 결과 연계해석 시 해저시설물의 안전율 및 이완하중고를 정확하게 산정하기 위해서는 집수정의 펌핑을 이용하여 유도배수하는 모델링 방법이 보다 정확하고 일관성 있는 결과를 얻을 수 있었다.

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Development of Direct Shear Apparatus with Different Loading Conditions for Rock Joints and Its Application Tests (하중조건별 시험이 가능한 암석 절리편 전단시험의 개발 및 적용시험)

  • 천병식;김대영
    • Journal of the Korean Geotechnical Society
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    • v.16 no.6
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    • pp.161-172
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    • 2000
  • 자연암석절리 및 인공 절리에 대하여 일정수직응력제어, 일정 수직하중제어 그리고 무한 강성제어가 가능한 암석 절리면 전단기 시험기를 개발하였다. 이 시험기는 전단변위에 의한 첩촉면적의 변화량을 계산하여 하중변화량을 조절하여 일정수직응력상태를 유지한다. 수직하중에 따른 시험기 강성에 의한 변화향이 제어 프로그램 내에서 제어되어 순수한 시편의 변위량을 출력하도록 하였다. 전단하중에 따른 시험기 강성에 의한 변위량은 상, 하부 전단상자의 상대변위 측정으로 최소화하였다. 전단거동 중의 자유도는 전당방향에 대하여 수평이도, 연직이동, 피칭, 롤링이 가능하도록 하였다. 자연절리면을 모사한 석고시편에 대하여 일정 수직응력 제어, 일정수직하중제어 그리고 무한 강성제어 조건으로 시험하여 제어상태 검증 및 비교를 하였다. 또한 경사각이 16.7˚와 22.6˚인 톱니형 시편에 대하여 시험한 결과 경사각 16.7˚와 22.6˚는 JRC로 10과 15를 나타내었으며, 첨두팽창각이 첨두전단강도에서 발생되며, Barton의 모델과 잘 일치함을 보였다.

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