DOI QR코드

DOI QR Code

Axial Behavior of Reinforced Concrete Columns Externally Strengthened with Unbonded Wire Rope and T-Shaped Steel Plate

와이어로프와 T 강판으로 비부착 보강된 철근콘크리트 기둥의 중심 축하중 거동

  • Published : 2008.04.30

Abstract

An improved unbonded-type column strengthening procedure using wire rope and T-shaped steel plate units was proposed. Eight strengthened columns and an unstrengthened control column were tested under concentric axial load. The main variables considered were the volume ratio of wire rope and the flange width and configuration of T-shaped steel plates. Axial load capacity and ductility ratio of columns tested were compared with predictions obtained from the equation specified in ACI 318-05 and those of conventionally tied columns tested by Chung et al., respectively. In addition, a mathematical model was proposed to evaluate the complete stress-strain relationship of concrete confined by the wire rope and T-plate units. Test results showed that the axial load capacity and ductility of columns increased with the increase of the volume ratio of wire rope and the flange width of T-plates. In particular, at the same lateral reinforcement index, a much higher ductility ratio was observed in the strengthened columns having the volume ratio of wire rope above 0.0039 than in the tied columns. A mathematical model for the stress-strain relationship of confined concrete using the proposed strengthening procedure is developed. The predicted stress-strain curves were in good agreement with test results.

와이어로프와 T형 강판을 이용한 개선된 비부착형 기둥보강 공법이 개발되었다. 제시된 절차에 따라 보강된 기둥 8개와 동일한 조건의 무보강 기둥 1개가 중심 축하중 하에서 실험되었다. 주요 변수는 와이어로프 체적비와 T 강판의 플랜지 폭 및 배치 형상이다. 실험된 기둥의 축하중 내력과 연성비는 각각 ACI 318-05의 예측값과 Chung et al.에 의해 수행된 일반 띠기둥의 실험 결과와 비교되었다. 게다가 와이어로프와 T 강판으로 구속된 콘크리트의 응력-변형률 관계를 평가하기 위한 모델이 제시되었다. 실험 결과로부터 기둥의 축하중 내력과 연성은 와이어로프의 체적비와 T 강판의 플랜지 폭의 증가와 함께 증가하였다. 특히 동일 횡보강근 지수에서 와이어로프 체적비가 0.0039 이상일 때 보강된 기둥의 연성비는 띠철근 기둥에 비해 현저히 높았다. 개발된 보강기술에 의해 구속된 콘크리트의 응력-변형률 관계 모델이 제시되었다. 예측된 응력-변형률 관계는 실험 결과와 잘 일치하였다.

Keywords

References

  1. Watson, R. J., "Column Retrofit of Short and Medium Span Bridges and Structures using High Strength Fiber Composites", In Proceeding Fourth International Conference on Short and Medium Span Bridges, 1994, pp.983-994
  2. Neale, K. W. and Demers, M., "Confinement of Reinforced Concrete Columns with Fiber-Reinforced Composite Sheets- An Experimental Study", Canadian Journal of Civil Engineering, Vol.26, 1999, pp.226-241 https://doi.org/10.1139/cjce-26-2-226
  3. Sheikh, S. A. and Yau, G., "Seismic Behavior of Concrete Columns Confined with Steel and Fiber-Reinforced Polymers", ACI Strucutural Journal, Vol.99, No.1, 2002, pp.72-80
  4. Hussain, M. A. and Driver, R. G., "Experimental Investigation of External Confinement of Reinforced Concrete Columns by Hollow Structural Sectiion Collars", ACI Structural Journal, Vol.102, No.2, 2005, pp.242-251
  5. Yang, K. H. and Ashour, A. F., "Tests of Reinforced Concrete Short Columns Strengthened with Wire Rope Unit", Magazine of Concrete Research, Vol.59, No.8, 2007, pp.547-557 https://doi.org/10.1680/macr.2007.59.8.547
  6. Bickford, J. H., An Introduction to the Design and Behavior of Bolt Joints, Marcel Dekker INC, 1990
  7. Kim, S. Y., Yang, K. H., Byun, H. Y., and Ashour, A. F., "Tests of Reinforced Concrete Beams Strengthened with Wire Rope Units", Engineering Structures, Vol.29, No.10, 2007, pp.2711-2722 https://doi.org/10.1016/j.engstruct.2006.12.013
  8. AISC, Manual of Steel Construction-Allowable Stress Design, American Institute of Steel Construction, 1989
  9. Saatcioglu, M. and Razvi, S. R., "Strength and Ductility of Confined Concrete", Journal of the Structural Engineering, ASCE, Vol.118, No.6, 1992, pp.1590-1607 https://doi.org/10.1061/(ASCE)0733-9445(1992)118:6(1590)
  10. Chung, H. S., Yang, K. H., Lee, Y. H., and Eun, H. C., "Strength and Ductility of Laterally Confined Concrete Columns", Canadian Journal of Civil Engineering, Vol.29, 2002, pp.820-830 https://doi.org/10.1139/l02-084
  11. ACI, Committee 318: Building Code Requirements for Structural Concrete (ACI 318-05) and Commentary (ACI 318R- 05), American Concrete Institute, 2005
  12. Razvi, S. and Saatcioglu, M., "Confinement Model for High-Strength Concrete", Journal of Structural Engineering, ASCE, Vol.125, No.3, 1999, pp.281-289 https://doi.org/10.1061/(ASCE)0733-9445(1999)125:3(281)
  13. Sakino, K. and Sun, Y., "Stress-Strain Curve of Concrete Confined by Rectilinear Hoop", Journal of Structural and Constructional Engineering, AIJ, No.461, 1994, pp.95-104
  14. Popovics, S., "Analytical Approach to Complete Stress-Strain Curves", Cement and Concrete Research, Vol.3, 1973, pp.583-599 https://doi.org/10.1016/0008-8846(73)90096-3