• Title, Summary, Keyword: 허용처짐

Search Result 36, Processing Time 0.041 seconds

Deflection Limit on Vibration Serviceability of High-speed Railway Bridges Considering the Effect of Train Speed (열차주행속도를 고려한 고속철도교량의 수직변위에 대한 진동사용성 한계(기준) 연구)

  • Jeon, Bub-Gyu;Kim, Nam-Sik;Kim, Sung-Il
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.473-476
    • /
    • 2011
  • 본 논문에서는 열차와 교량의 상호작용과 주행속도에 의해 결정되어지는 진동지속시간과 차체연직가속도 증폭효과를 고려하여 철도교량의 진동사용성 허용처짐을 제시하고자 하였다. 열차가 교량을 통과할 때의 처짐 형상을 사인파로 가정하고 열차와 교량의 상호작용을 진동전달함수로 표현하여 철도교량의 진동 사용성 허용처짐을 유도하였다. 그리고 진동지속시간을 고려하기 위해 연직가속도 허용기준으로서 진동지속시간을 고려한 교량구조물의 진동사용성기준을 사용하였다. 매개변수연구를 통하여 열차 주행속도의 증가에 비례하여 차체연직가속도는 증가하지만 교량최대변위의 변화는 미미함이 확인됨으로 인하여 차체연직가속도 증가와 동반하여 연직가속도 허용기준역시 증가하는 것을 보정할 필요가 있을 것으로 판단하였다. 따라서 전개된 철도교량의 진동사용성 허용처짐식에 매개변수연구를 통하여 가정한 가속도 증폭계수를 적용하여 열차의 증속에 의한 가속도증폭효과를 고려하였다.

  • PDF

Estimation of Stiffness Limit for Railway Bridge Vibration Serviceability (진동사용성을 고려한 철도교량구조물의 강성한계 분석)

  • Jeon, Bub-Gyu;Kim, Nam-Sik;Kim, Sung-Il
    • Journal of the Korean Society for Railway
    • /
    • v.11 no.5
    • /
    • pp.489-498
    • /
    • 2008
  • In general, deflection limit criteria of bridge design specifications have been considered based on static serviceability and structural stability. Dynamic serviceability induced from bridge vibration actually has not been included in the criteria. Thus, it is necessary for deflection limit to be considered in order to check dynamic service- ability on bridge vibration. In this study, The allowable displacement of Korea Railway Bridge Design Specifications is compared to the frequency domain comfort limit and analyzed france code and japanese code. Korea Railway Bridge Design Specifications is regulated based on the train speed. Such is because the vibration time duration is partly considered. but this criteria is not satisfied with comfort limit. and, it is estimated to be capable to provide deflection limit considering dynamic serviceability. In order to evaluate the dynamic serviceability of various types of railway bridges in current public were selected and their dynamic signals were measured. and the result of the bridge-train interaction analysis according to the changes in bridge stiffness was compared to the comfort limit to suggest the stiff-ness limit to the dynamic serviceability, which should conveniently be applied at the field.

Deflection Limit based on Vibration Serviceability of Railway Bridges Considering the Correlation between Train Speed and Vertical Acceleration on Coach (열차의 주행속도와 차체연직가속도의 상관관계를 고려한 철도교량의 진동사용성 처짐 한계)

  • Jeon, Bub-Gyu;Kim, Nam-Sik;Kim, Sung-Il
    • Journal of the Korean Society for Railway
    • /
    • v.14 no.6
    • /
    • pp.545-554
    • /
    • 2011
  • In order to get dynamic serviceability of a train travelling on a railway bridge, comfort limits with the deflection of bridge and vertical acceleration on car body are proposed in Eurocode, Shinkansen design criteria, The design guideline of the Honam High-speed railway. The design guideline of the Honam High-speed railway has quoted Eurocode. Therefore it is expected that supplementation of comfort limit of railway bridge according to expansion of span length and the improvement traveling speed of trains in the future would relatively fall behind developed countries in railway. Therefore, in order to secure technological competitiveness in world market, the study was conducted to propose the deflection limit based on vibration serviceability of railway bridges that can consider bridge-train interaction and travelling speed increase. The parameter study and bridge-train dynamic interaction analysis was conducted to figure out the correlation of vertical acceleration on car body and bridge displacement according to the increase in travelling speed. Also, the trend of increasing vertical acceleration on car body according to the increase in travelling speed was confirmed, and the amplification coefficient of vertical acceleration on car body was suggested. And the deflection form and vibration of the bridge were assumed to be in harmonic motion, and transfer function and the amplification coefficient were used to develop the dynamic serviceability deflection limit of the high-speed railway bridge as a formula.

The Displacement Limit at the End of an Approach Slab for a Railway Bridge with Ballastless Track (콘크리트궤도 부설 교량의 접속슬래브 단부 처짐한도에 관한 연구)

  • Choi, Jin-Yu;Yang, Shin-Chu
    • Journal of the Korean Society for Railway
    • /
    • v.11 no.2
    • /
    • pp.195-202
    • /
    • 2008
  • The transition area between a bridge and an earthwork is one of the weakest area of track because of the track geometry deterioration caused unequal settlement of backfill of abutment. In case of a ballastless track, the approach slab could be installed to prevent such a phenomenon. But, if there is occurred the inclined displacement on the approach slab by a settlement of the foundation or formation, the track is also under the inclined displacement. And this defect causes reducing the running stability of a vehicle, the riding comfort of passengers, and increasing the track deteriorations by excessive impact force acting on the track. In this study, parametric studies were performed to investigate the displacement limit on the approach slab to avoid such problems. The length and the amount of unequal settlement of approach slab were adopted as parameter for numerical analysis considering vehicle-track interaction. Car body accelerations, variations of wheel force, stresses in rail, and uplift forces induced on fastener clip were investigated. From the result, resonable settlement limit on the end of an approach slab according to slab length was suggested.

Analysis of Nonlinear Behavior and Reliability of PSSC Composite Girder Bridge (PSSC 합성거더 교량의 비선형 거동 분석 및 신뢰도 해석)

  • Hwang, Chul-Sung;Paik, In-Yeol
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.12 no.1
    • /
    • pp.158-166
    • /
    • 2008
  • Member force, strain and stress distribution of a section are obtained for prestressed steel and concrete(PSSC) composite bridge subjected to dead and live load in order to interpret the effect of prestressing and deformation of tendon. The stress and strain distribution and moment capacity are obtained for both noncomposite and composite section and for allowable stress limit state, yield limit state and strength limit state. Reliability analysis is conducted after assuming limit states for deflection, stress and flexural strength. Comparing that the reliability index for stress is near 0 for example section which is designed to satisfy the allowable stress exactly, the reliability indexes for deflection and flexural strength are high. Reliability of PSSC girder which is designed based on allowable stress of bridge design code is high for deflection and flexural strength.

Limit Span/Depth Ratio for Indirect Deflection Control in Reinforced Concrete Flexural Members (철근콘크리트 휨부재의 처짐 간접제어를 위한 한계 지간/깊이-비 연구)

  • Choi, Seung-Won;Kim, Woo
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.31 no.1A
    • /
    • pp.35-41
    • /
    • 2011
  • In concrete structural design provisons, two methods are normally provided to control deflection; direct method and indirect method. It is more efficient to use the indirect deflection control by which the span/depth ratio is limited not to exceed an allowable deflection limit. Because actual deflections are affected by many causes, it is complicated to evaluate actual deflections. In this study, limit span/depth ratios are derived from the deflection calculated directly at the serviceability limit state in RC members. The deflection is obtained from using average curvature, which depends on materials model used. The main variables examined are tension stiffening effect, concrete strength, cross section size and compressive steel ratio. It could be appeared that more analytical consistency is secured to use the 2nd order form of tension stiffening effect. And the limit span/depth ratio is dependent on material strength, tensile and compressive steel ratio but it is independent on cross-section size.

중수로 압력관 두께 변화 예측

  • 송택호;장창희
    • Proceedings of the Korean Nuclear Society Conference
    • /
    • /
    • pp.789-794
    • /
    • 1998
  • 원전수명관리 측면에서 경수로와 중수로를 비교해 보면, 경수로의 경우 원자로 압력용기가 주요기기중 가장 중요한 위치에 있는 반면에 중수로는 압력관이 가장 중요한 기기이다. 압력관 손상종류는 DHC와 dimensional change로 크게 분류되는데 dimensional change는 creep, 부식마모, 처짐현상으로 구분된다. 본 논문에서는 creep과 부식마모 현상 발생시 예상되는 압력관 두께 변화를 계산하였으며, 중수로 수명관리 측면에서 가동 시작년도부터 50년까지 변화되는 두께를 ASME 허용기준과 비교하였다. creep과 부식마모에 의하여 감소 예상되는 압력관 두께는 50년까지 모두 ASME 허용 Margin안에 있음을 볼 수 있었다.

  • PDF

An Experimental Study on the Long-Term Deflection of Concrete Beams with GFRP Rebars (FRP 보강 콘크리트 보의 장기처짐에 관한 실험연구)

  • Park, Ji-Sum;You, Young-Jun;Park, Young-Hwan;Kim, Keung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.325-328
    • /
    • 2008
  • This study is to investigate experimentally the long-term deflection of concrete beams with glass fiber reinforced polymer (GFRP) reinforcing bars subjected to the sustained flexural load for periods of up to 6 months. A total of four beams were tested. All beams were designed with net span of 2,700 mm and rectangular cross-section of 200 mm width and 300 mm depth. From the test results the time-dependent deflection of concrete beams with GFRP bars was about 40 to 70% of the initial deflection. As well as this paper compares the long-term deflection calculated by 440.1R-06 design guide and that of tested beams. The comparison indicated that the calculated long-term deflection overestimate the observed long-term deflection of concrete beams with FRP rebars.

  • PDF

Tests on the Flexural and Shear Behavior of Partially Prestressed Concrete Beams(II) -About the Deflection and Crack (부분(部分) 프리스트레스트 콘크리트 부재(部材)의 휨 및 전단(剪斷) 실험(實驗)(II) -처짐과 균열에 대(對)하여)

  • Chang, Sung Pil;Kang, Won Ho
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.9 no.4
    • /
    • pp.41-49
    • /
    • 1989
  • Following the previous paper, the results of test are further presented. As partially prestressed concrete members permit cracks under the service state, deflection and crack control of partially prestressed concrete members is more important than that of reinforced or fully prestressed concrete members. By the test results of load-deflection relation, it can be shown that prestressing ratio significantly affects the behavior of partially prestressed concrete beams. Deflection prediction formula of some codes are tried, and test results are compared with various fomulae of crack spacing and crack width.

  • PDF

Damage Detection in Steel Box Girder Bridge using Static Responses (강박스 거더교에서 정적 거동에 의한 손상 탐지)

  • Son, Byung Jik;Huh, Yong-Hak;Park, Philip;Kim, dong Jin
    • Journal of The Korean Society of Civil Engineers
    • /
    • v.26 no.4A
    • /
    • pp.693-700
    • /
    • 2006
  • To detect and evaluate the damage present in bridge, static identification method is known to be simple and effective, compared to dynamic method. In this study, the damage detection method in steel box girder bridge using static responses including displacement, slope and curvature is examined. The static displacement is calculated using finite element analysis and the slope and curvature are determined from the displacement using central difference method. The location of damage is detected using the absolute differences of these responses in intact and damaged bridge. Steel box girder bridge with corner crack is modeled using singular element in finite element method. The results show that these responses were significantly useful in detecting and predicting the location of damage present in bridge.

  • PDF