• Title, Summary, Keyword: Span Length

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Eigenvalue Analysis of Double-span Timoshenko Beams by Pseudo spectral Method

  • Lee, Jin-Hee
    • Journal of Mechanical Science and Technology
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    • v.19 no.9
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    • pp.1753-1760
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    • 2005
  • The pseudo spectral method is applied to the free vibration analysis of double-span Timoshenko beams. The analysis is based on the Chebyshev polynomials. Each section of the double-span beam has its own basis functions, and the continuity conditions at the intermediate support as well as the boundary conditions are treated separately as the constraints of the basis functions. Natural frequencies are provided for different thickness-to-length ratios and for different span ratios, which agree with those of Euler-Bernoulli beams when the thickness-to-length ratio is small but deviate considerably as the thickness-to-length ratio grows larger.

Assessment of the Degree of Fatigue Damage in Steel Plate-Girder Railway Bridges According to Span Length (지간장에 따른 강판형 철도교의 피로피해도 평가)

  • Jung, Young-Hwa;Kim, Ik-Gyeom;Kim, Ji-Hun;Nam, Wang-Hyone
    • Journal of Industrial Technology
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    • v.19
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    • pp.313-320
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    • 1999
  • Steel railway bridge gets vibration from moving load ; additionally, this kind of moving load is going to be a sufficient reason, which causes fatigue damage to steel railway bridge. Fatigue damage and stress curve were raised by moving load depends on span length in steel railway bridge. In other words, stress curve appears index regarding every axial load in short span, but self weight lets stress curve's change decrease in proportion to increasing span length. Thereby, we have studied that how the steel railway bridge appear fatigue damage in proportion to span length of steel railway bridge. Dynamic strain was measured in 4 steel plate-girder railway bridge during the trains was passing, which is located on the line of Kyoung-chun railway. And time history response analysis has been done in order to ensure actual survey. The results of this study show the decreased of the fatigue damage in steel railway bridge according to length of span. This paper ends is bases research of fatigue design in steel railway bridges according to span length.

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Span limit and parametric analysis of cable-stayed bridges

  • Zhao, Xinwei;Xiao, Rucheng;Sun, Bin
    • Structural Engineering and Mechanics
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    • v.71 no.3
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    • pp.271-282
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    • 2019
  • The span record of cable-stayed bridges has exceeded 1,000 m, which makes research on the maximum possible span length of cable-stayed bridges an important topic in the engineering community. In this paper, span limit is discussed from two perspectives: the theoretical span limit determined by the strength-to-density ratio of the cable and girder, and the engineering span limit, which depends not only on the strength-to-density ratio of materials but also on the actual loading conditions. Closed form equations of both theoretical and engineering span limits of cable-stayed bridges determined by the cable and girder are derived and a detailed parametric analysis is conducted to assess the engineering span limit under current technical conditions. The results show that the engineering span limit of cable-stayed bridges is about 2,200 m based on materials used available today. The girder is the critical member restricting further increase in the span length; its compressive stress is the limiting factor. Approaches to increasing the engineering span limit are also presented based on the analysis results.

Comparison of the Effects of Different Crutch Length Measurement Methods on Trunk Muscle Activities in Young Females (젊은 여성의 몸통 근육 활성도 분석을 통한 목발 길이 측정 방법의 효율성 비교)

  • Jeon, Hyun;Oh, Duck-Won
    • Journal of the Korean Society of Physical Medicine
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    • v.15 no.1
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    • pp.77-84
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    • 2020
  • PURPOSE: This study compared the activities of the trunk muscles during crutch walking to determine which of the crutch length measurements is most beneficial. METHODS: Twenty young women volunteered to participate in this study. After adjusting crutch length, the participants performed a three-point walking with nondominant leg limited in weight bearing. This study used six crutch length measurements: (1) Height-40.6cm, (2) Height'.77, (3) Olecranon-to-finger length, (4) Axillary-toheel length, (5) Arm-span length-40.6cm, and (6) Arm-span length'.77. The EMG activities of the internal oblique (IO), rectus abdominis (RA), multifidus (MF), and erector spinae (ES), muscles on the weight bearing side were monitored using wireless surface EMG. RESULTS: The EMG activities of the RA and ES appeared to be significantly different among the crutch length measurements (p<.05). The post-hoc test showed that the 'Arm-span length-40.6cm' was significantly greater in the RA activity when compared to the 'Height'.77' and 'Axillary-to-heel length' measurements, and in the ES activity when compared to 'Height'.77' measurements. Furthermore, IO/RA and MF/ES ratios showed significant differences among the crutch length measurements (p<.05). In the post-hoc test, significant difference was observed between 'Olecranon-to-finger length' and 'Arm-span length-40.6cm' for the IO/RA ratio, and between 'Height'.77' and 'Olecranon-to-finger length' and between 'Height'.77' and 'Arm-span length-40.6cm' measurement for the MF/ES ratio. CONCLUSION: These findings suggest that the 'Height'.77' measurement is relatively advantageous to optimize the activities of trunk muscles during the crutch walking, and allow simple measurements of the crutch length.

Optimization of Net Residual Dispersion and Launching Power Depend on Total Transmission Length and Span Length in Optical Transmission Links with Dispersion Management and Optical Phase Conjugation (분산 제어와 광 위상 공액이 적용된 광전송 링크에서 총 전송 거리와 중계 간격에 따른 전체 잉여 분산과 입사 전력의 최적화)

  • Lee, Seong-Real
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.12B
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    • pp.1433-1441
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    • 2011
  • Design rules of optical transmission links with dispersion management (DM) and optical phase conjugation (OPC) for compensating optical signal distortion due to chromatic dispersion and self phase modulation (SPM) of single mode fiber (SMF) are investigated in this paper. Design rules consist of optimal net residual dispersion (NRD) and optimal range of launching power of wavelength division multiplexed (WDM) channels as a function of total transmission length and span length. In all considered total transmission length and span length, optimal NRD are obtained to +10 ps/nm and -10 ps/mn for transmission links, which is controlled by precompensation and postcompensation, respectively. It is confirmed that system performances are more improved and effective NRD for wide launching power have wider range as total transmission length and span length are more decreased.

Comparison of Girder Height by Span in Various Types of Railway Bridge (철도교량형식의 경간에 따른 형고 비교)

  • Lee, Tae-Gyu;Kim, Hye-Uk
    • Proceedings of the KSR Conference
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    • pp.262-267
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    • 2008
  • The type used mainly in present our country in the superstructure of the railway bridge including the high speed railway is classified by the box girder and the I-type girder, greatly. The box girder is mainly used by the high speed railway bridge, and the I-type girder is used mostly by general railway bridge style. In this study, according to current railway bridge design code, we execute design by the span length of each considered bridge form. Also we analyze the suitable girder height by the span length and calculate the construction costs. The comparative analysis of the structural efficiency is produced by the span length. From this study, it is exposed that the girder height by the span length is the biggest in box girder. Also it is evaluated that the construction costs of the box girder is higher than that of the I-type girder although there is a difference between more or less according to adopted construction method.

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Change of Bending Properties of 2×4 Larch Lumber According to Span Length in the Four Point Bending Test (4점 휨 시험에서 지간 거리에 따른 2×4 낙엽송 제재목의 휨 성능 변화)

  • Kim, Chul-Ki;Kim, Kwang-Mo;Lee, Sang-Joon;Park, Moon-Jae
    • Journal of the Korean Wood Science and Technology
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    • v.46 no.5
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    • pp.486-496
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    • 2018
  • This study was conducted to confirm an effect of span length on bending properties of larch dimensional lumber in the four point bending test. The size of specimen in this study was 38 (width) ${\times}$ 89 (depth) ${\times}$ 3,600 (length) $mm^3$, and average air-dry density and moisture content of the specimens was $543.5kg/m^3$ and 10.5%, respectively. Visually graded No. 1 dimensional lumbers of 248 were divided by two groups to compare modulus of rupture (MOR) and modulus of elasticity (MOE). One group was tested in the four point bending test with span length of 1,650 mm, and other was tested with span length of 3,000 mm. While MOE was not different according to span length in 5% significance level, MOR was different in accordance with span lengths and was in inverse proportion to change of span length. Fifth percentiles of MOR in span length of 1,650 and 3,000 mm were 28.65 and 25.70 MPa, respectively. It was confirmed that the difference between MORs in each case increased as normalized rank increased. This is because of size effect in Weibull weakest link failure theory. Therefore, KS F 2150, in which there is only regulation about span to depth ratio of 15 or more, is needed to be revised to contain a method considering size effect for MOR. From the method, various results of bending test with different size of lumber could be used to determine design value of lumber.

Design Bending Moment of Cantilever Slab for Long Span decks with KL-510 Load (KL-510 하중을 적용한 장지간 바닥판의 캔틸레버부 설계휨모멘트)

  • Chung, Chulhun;Joo, Sanghoon;Lee, Hanjoo
    • Journal of The Korean Society of Civil Engineers
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    • v.36 no.4
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    • pp.595-604
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    • 2016
  • This paper proposed the design bending moments of cantilever slabs with KL-510 load according to span length of long span decks. Their span length range is from 6.0 to 12.0 meter, and length of cantilever slabs is from 30 to 50 percent of their span length. The effects of orthotropic concrete decks, stiffness of steel girders and multiple lane loading factors (MLLF) were reflected in the design bending moments. The proposed design bending moments of cantilever slabs were compared to the design bending moments with DB-24 load.

A study on method of maximum span length calculation of catenary system (전차선로 최대경간 길이 계산기법 고찰)

  • 윤장원;이기원;김주락;이상중;창상훈
    • Proceedings of the KSR Conference
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    • pp.316-321
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    • 2001
  • The maximum span length is decided by the relation among the independent factors of rail, train and catenary. However, During the calculation of the maximum span length with the way of Kyung-Bu High railway design using by the commercial program $\ulcorner$MATLAB$\lrcorner$ the mathematical error was founded. Therefore, this paper presents the analysis of the reason why caused the mathematical error occur.

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A Study on the Optimized Biarc Curve Fitting of Involute Curve (인벌류트 곡선의 Biarc Curve Fitting 최적화에 관한 연구)

  • Cho, Seung-Rae;Lee, Choon-Man
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.4
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    • pp.71-78
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    • 1999
  • The determination of the optimum biarc curve passing through a given set of points along involute curve is studied. The method adopted is that of finding the optimum number of span and the optimum length of the span such that error between the biarc curve and involute curve minimum. Iterative method is effectively used to find the optimim number and length of the span on involute curve with reduced length of NC-code.

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