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Study on the effect of cable on the lateral behavior of S-shaped Pedestrian-CSB

S형 보도사장교의 케이블이 횡방향 거동에 미치는 영향 연구

  • 지선근 (서울시립대학교 토목공학과) ;
  • 임성순 (서울시립대학교 토목공학과)
  • Received : 2019.03.12
  • Accepted : 2019.05.03
  • Published : 2019.05.31

Abstract

Recently, CSB(Cable-Stayed Bridge) have been attempted to be atypical forms for landscape elements in Korea. CSB with new geometry need to analyze their characteristics clearly to ensure structural safety. This study's bridge is the S-shaped curved pedestrian CSB that has a girder with S-shape plane curve and reverse triangular truss cross section, inclined independent pylon, modified Fan type main cable and vertical backstay cable. Curved CSB can have excessive lateral displacement and moment when the tension is adjusted, focusing only on longitudinal behavior, such as a straight CSB. In order to analyze the effect of the cable on the lateral behavior of bridges, the cable is divided into two groups according to the lateral displacement direction of the pylon due to tension. The influence of the combination ratio of GR1 and GR2 on the girder, bearing, pylon, and vertical anchor cable was analyzed. When the tension applied to the bridge is 1.0GR1 plus 1.0GR2, In the combination of 1.2GR1 plus 0.8GR2, the stress on the left and right upper member of the truss girder and the deviation of the both were minimized. In addition, the horizontal force of the bearing, the lateral displacement and moment of the pylon, and the tension of the vertical backstay cable also decreased. This study is expected to be used as basic data for determination of tension of CSB with similar geometry.

최근 국내 사장교는 경관적인 요소를 위하여 비정형적인 형태가 시도되고 있다. 새로운 기하구조가 적용된 사장교는 그 특성을 명확히 분석하여 구조안전성을 확보할 필요가 있다. 본 연구 대상 교량은 S자형 곡선 보도사장교로 S자형 평면곡선과 역삼각형트러스 횡단면을 가진 보강거더, 곡선반경 내측에 1면으로 배치된 경사 주탑과 modified Fan 타입 주케이블, 수직 백스테이케이블이 적용되었다. 곡선사장교는 직선사장교와 같이 종방향의 거동에만 초점을 두고 장력을 조정할 경우 횡방향으로 과다한 변위와 모멘트가 발생 할 수 있다. 본 연구는 주케이블이 교량의 횡방향 거동에 미치는 영향을 분석하기 위해서, 장력에 의한 주탑의 횡방향 변위 방향에 따라 케이블을 2개 그룹으로 나누었다. 지간중앙부 케이블 그룹을 GR1, 주탑지점부 케이블 그룹을 GR2라 할 때 GR1과 GR2의 조합비율이 보강거더, 받침, 주탑 그리고 수직앵커케이블에 미치는 영향을 분석하였다. 연구대상 교량에 적용된 장력비율을 1.0GR1+1.0GR2라 하였을 때, 1.2GR1+0.8GR2의 조합에서 주탑지점부 보강거더의 좌측과 우측 상현재 응력이 최소가 되었고, 좌우 부재의 편차도 최소가 되었다. 또한, 받침의 수평력, 주탑의 횡방향 변위와 모멘트, 수직백스테이케이블의 장력도 감소하였다. 본 연구는 유사한 기하구조를 가진 사장교의 장력 결정시 기초 자료로 활용될 것으로 기대된다.

Keywords

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Fig. 1. Outline Of Bridge Plans (a)Plan View (b)Cross Section of Girder on Pier1 (c)Vertical View (d)Cross Section of Girder on Pier2

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Fig. 2. Torsion Direction of Girder without Cable

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Fig. 3. Deformed Shape of Truss Girder witn Case1 (a)Truss Girder on Pier1 (b)Truss Girder on Pylon1

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Fig. 4. Transverse Arrangement of Cable

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Fig. 5. Analysis Modeling

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Fig. 6. Cable Group (a)Cable Group1 (b)Cable Group2 (c)Pylon1 deformed shape by cable group1 (d)Pylon1 deformed shape by cable group2

SHGSCZ_2019_v20n5_577_f0007.png 이미지

Fig. 7. Girder Moment due to Tension of Cable Group1 (a)My (b)Mz (c)Mx

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Fig. 8. Girder Moment due to Tension of Cable Group2 (a)My (b)Mz (c)Mx

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Fig. 9. Pattern Diagram

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Fig. 10. Transver Moment Diagram of Pylon1

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Fig. 11. Mode Shape (a)mode2 (b)mode5

Table 1. Direction of Torsion Deformation

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Table 2. Stress of Girder due to Combination GR1&GR2

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Table 3. Horizontal Force of Bearing due to Combination GR1&GR2

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Table 4. Displacement of Pylon due to Combination GR1&GR2

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Table 5. Tension of vertical BackStay Cable due to Combination GR1 and GR2

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Table 6. Equivalent elastic modulus

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Table 7. Frequency of Eigenvalue Analysis

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