• Title/Summary/Keyword: 온도하중

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Thermal Behavior and Structral Efficiency of Rahmen with Sliding-Girder (슬라이딩 거더를 가진 라멘의 온도거동과 구조효율)

  • Jeong, Dal-Yeong;Jeong, Chang-Hyun;Yhim, Sung-Soon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.1
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    • pp.1-7
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    • 2020
  • Although the temperature load is an important load among the various loads affecting the behaviors of general rahmen-type temporary bridges (GRTB), no study of the thermal load has been carried out. In the case of GRTB, horizontal displacement should be free, and the generated internal force should be minimized to reduce stress due to a temperature load. Sliding girder type bridge (SGTB) allows the axial deformation due to thermal load, and decreases the axial stress and delivers bending stress. This study examined the temperature behavior of an SGTB. Structural analysis was carried out for four types of spans (eq, 10, 20, 30, and 40m) and three types of pier heights (eq, 2, 4, and 6m) along with the GRTB. The applied loads were a fixed vertical load and an axial temperature load. The friction coefficient was 0.4, which is a representative value of a steel girder. Consequently, the stress of the SGTB increased with increasing span length, regardless of the temperature load. The stress of the GRTB increased with increasing temperature and span length. Compared to the GRTB, the stress of the SGTB decreased by 20% to 50% at the center of the girder and by 50% to 90% at the bottom of the pier. This could secure the structural efficiency compared to the GRTB with the same specifications.

Construction Sequential Analysis on RC Building Structure considering Temperature Changes (외부 온도변화를 고려한 RC 건축구조물의 시공단계해석)

  • Kang, Su-Min;Oh, Jae-Keun;Kim, Ook-Jong;Lee, Do-Bum
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.229-232
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    • 2008
  • In rapid cycle construction, RC structure which is not cured fully can be loaded with construction load and this construction load can influence on the safety of construction and cracks on slabs. Therefore, to reduce the term of construction, the safety of construction and prevention of cracks should be assured against construction load. In the previous study, temperature load can significantly influence on the behavior of structure under construction. However, existing construction sequential analysis or design code do not consider temperature load reasonably. In the present study, through construction sequential analysis method using FE analysis, the behavior of structure under construction was analyzed according to temperature changes. According to the results of analysis, as the temperature falls, shoring load drops and the temperature rises, shoring load rises. These variations of shoring load can affect the safety of construction. Moment of slab goes up by fall in temperature. This increase of moment can cause cracks on the slab. Therefore to assure the safety on construction and prevent cracks on slabs, temperature load has to be considered reasonably in construction sequential analysis.

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Design Thermal Loads In Composite Box Girder Bridges (합성형교량의 설계온도하중)

  • Chang, Sung Pil;Im, Chang Kyun
    • Journal of Korean Society of Steel Construction
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    • v.10 no.3
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    • pp.537-551
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    • 1998
  • The intention of this paper is to provide realistic values of design thermal loads applicable to composite box girder bridges on the basis of the statistical analysis of long-term measured temperature data. For this purpose, temperatures were recorded at a newly constructed composite box girder bridge during about 20 months. Before analyzing the extreme values, major thermal loading parameters that characterize the temperature profile are defined, and a seasonal behavior of those is examined in detail. The limit distributions of the thermal loading parameters are then determined by the tail-equivalence method, and the thermal loading parameters corresponding to selected return period are calculated. Finally, the results are compared to the specifications suggested in a current design code for thermal loads, and it is concluded that the current design code is unsuitable for representing the self-equilibrated thermal stresses in composite bridges, and the horizontal temperature difference which is not suggested in current design code should be taken Into account in particular cases.

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Characteristics on the Temperature Distribution in Steel Girder Bridge by using Gauge Measurement (계측에 의한 강거더교의 온도분포 특성)

  • Lee, Seong-Haeng;Cheung, Jin-Hwan;Kim, Kyoung-Nam;Hahm, Hyung-Gil;Jung, Kyoung-Sup
    • Journal of Korean Society of Steel Construction
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    • v.23 no.3
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    • pp.283-294
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    • 2011
  • The variation of temperature in the steel girder bridge by air temperature is measured. A correlation between the daily temperature range, the maximum and minimum temperatures of the day, and the temperature of the bridge are analyzed. With the statistical data from the Korea Meteorological Administration, the temperature correlations analyzed in this study is able to predict temperature variations between the upper flange and the lower flange which calculates the realistic displacement values of a movable support and an expansion joint in design.

Nonlinear analysis of containment structure under thermal and pressure load (원자로 격납건물의 열응력해석연구)

  • 오병환;이명규
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.219-224
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    • 1993
  • 본 연구는 철근콘크리트 격납구조물에서 가상의 냉각제 유출사고에 의한 온도하중과 압력에 따른 거동을 알아보기 위한 비선형 해석을 수행하였다. 시간에 따른 온도하중을 결정하기 위하여 과도온도해석을 통해 격납구조물 단면내의 온도분포를 구하였다. 구조물은 기하학적 비선형성과 재료비선형성을 고려한 판 및 쉘요소로 이상화되며, 쉘요소는 두께방향에 따라 변하는 응력을 고려하기 위해 몇 개의 층으로 이루어진 모델을 사용하였다. 열응력은 인접한 두시간 단계에서의 온도차를 하나의 하중증가로 고려하여 초기변형 문제로 변환하여 결정되었다. 본연구에서의 수치실험에 의하여 과도온도해석에 근거한 비선형온도경사를 고려할 때의 변위가 고려하지 않을 때의 변위에 비해 크게 나타남을 알 수 있다.

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Variation of Rail's Axial Compressive Force on Railway Bridges Due to Thermal and Seismic Loads with using EQS Bearings (EQS 면진받침 사용 시 온도하중 및 지진하중에 대한 철도교량 레일 압축력 변화)

  • Kim Lee Hyeon;Kim Haksoo;Choi Eunsoo
    • Journal of the Korean Society for Railway
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    • v.8 no.3
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    • pp.276-285
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    • 2005
  • This study discussed the effect on rail's axial force due to thermal and seismic loads according to supporting conditions of railway bridges; the considered supporting conditions are 1)simply supported, 2)roller at both ends, and 3)roller with horizontal spring at both ends. Closed form solutions are used to calculate the axial farces on rails. The roller at both ends of a bridge span decreases the compressive axial force on rail due to thermal load compared with the simply supported condition. However, the lateral springs at roller are not helpful to decrease the rail's compressive axial force.

Experimental Analysis of Curling Behavior of Concrete Slabs on Grade under Temperature Loading and Underlying Layers' Effects (지반위에 놓인 콘크리트 슬래브의 온도하중 하의 컬링 거동 및 하부층 영향 실험적 분석)

  • Kim, Seong-Min;Park, Hee-Beom
    • International Journal of Highway Engineering
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    • v.10 no.4
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    • pp.171-180
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    • 2008
  • This study was conducted to analyze the curling behavior of concrete slabs on grade under temperature loading through the laboratory tests and to investigate the effects of the support conditions of underlying layers on the curling behavior of the slab on grade systems. For the laboratory tests, the concrete slabs were fabricated and the temperature measurement sensors were installed. The temperature loading was applied intentionally and the time histories of the vertical displacements of the slab at several different positions were measured. One-layered underlying layers were made using different materials and different thicknesses. Two-layered underlying layers were also made to have the same composite stiffness each other, but the material of the upper layer was designed to be different The experimental analysis results showed that the trend of the displacement time histories of the slab was basically the same as that of the temperature gradient time histories. The characteristics of the curling behavior of the slab were analyzed by separating the regions of curling up and curling down. The difference in the vertical displacements at the center and comer decreased as the stiffness of the underlying layer became larger, and the upper layer's material of the underlying layers affected the curling behavior of the slab.

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Design Review of Inter-Modal Terminal Platform for Temperature Load (온도하중을 고려한 인터모달 터미널 플랫폼의 설계 검토)

  • Kim, Kyoung-Su;Kim, Da-Ae;Kim, Heung-Rae;Hyun, Eun-Tack
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.5
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    • pp.305-311
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    • 2019
  • In this study, we examined the proper spacing between the expansion joints according to the temperature load of the inter-modal terminal platform infrastructure to implement a new inter-modal automated freight transport system, which we intend to introduce in Korea. To review the proper expansion joint spacing of the terminal platforms, we set the maximum expansion joint spacing according to the regional temperature changes using the equation proposed by the Federal Construction Council (FCC) of the United States. Then, the maximum displacement value, which was calculated through the structural analysis program, and the limit of the horizontal displacement of the building structure were compared. The proper expansion joint spacing was selected as the slab length at which the maximum displacement of the structure, due to temperature changes, was below the horizontal displacement limit. Based on the application of maximum expansion joint spacing for each region calculated through the FCC's suggestion, the maximum displacement that could occur within the limit of the lateral displacement of the structure was determined.