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경량콘크리트 연속보의 전단내력에 대한 골재크기의 영향

Effect of Aggregate Size on the Shear Capacity of Lightweight Concrete Continuous Beams

  • Yang, Keun-Hyeok (Dept. of Architectural Engineering, Mokpo National University) ;
  • Mun, Ju-Hyun (Dept. of Architectural Engineering, Mokpo National University)
  • 발행 : 2009.10.31

초록

철근콘크리트 연속 보의 전단거동에 대한 골재 최대직경의 영향을 평가하기 위하여 24개의 실험체가 실험되었다. 전경량, 모래경량 및 보통중량콘크리트 보에서 최대 골재직경은 4 mm에서 19 mm로 변하였으며, 전단경간비는 2.5와 0.6으로 있었다. 보통중량콘크리트 보의 무차원 최대전단내력에 대한 동일조건의 경량콘크리트 보의 무차원 최대 전단내력의 비가 ACI 318-05에서 제시하는 수정계수와 비교되었다. 파괴면에 대한 현미경 사진으로부터 경량콘크리트보의 파괴면은 주로 골재를 관통하지만 파괴되지 않은 경량골재들도 다수 발견되었는데, 이는 경량콘크리트 보의 전단거동 향상에 기여하였다. 이로 인해 경량콘크리트 연속 보의 최대전단내력은 골재 최대직경의 증가와 함께 증가하였는데, 그 증가기울기는 보통중량콘크리트 연속보에 비해 낮았다. ACI 318-05에서 제시하는 수정계수는 경량콘크리트 연속 보에서는 다소 불안전측에 있었는데, 그 불안전측은 최대 골재직경의 증가와 함께 증가하였다. 또한 ACI 318-05의 전단규정에 대한 안전성은 보통중량콘크리트 보에 비해 경량콘크리트 보에서 낮았다.

Twenty-four beam specimens were tested to examine the effect of the maximum aggregate size on the shear behavior of lightweight concrete continuous beams. The maximum aggregate size varied from 4 mm to 19 mm and shear span-to-depth ratio was 2.5 and 0.6 in each all-lightweight, sand-lightweight and normal weight concrete groups. The ratio of the normalized shear capacity of lightweight concrete beams to that of the company normal weight concrete beams was also compared with the modification factor specified in ACI 318-05 for lightweight concrete. The microphotograph showed that some unsplitted aggregates were observed in the failure planes of lightweight concrete beams, which contributed to the enhancement of the shear capacity of lightweight concrete beams. As a result, the normalized shear capacity of lightweight concrete continuous beams increased with the increase of the maximum aggregate size, though the increasing rate was lower than that of normal weight concrete continuous beams. The modification factor specified in ACI 318-05 was generally unconservative in the continuous lightweight concrete beams, showing an increase of the unconservatism with the increase of the maximum aggregate size. In addition, the conservatism of the shear provisions of ACI 318-05 was lower in lightweight concrete beams than in normal weight concrete beams.

키워드

참고문헌

  1. ACI-ASCE Committee 426, "The Shear Strength of Reinforced Concrete Members," Proceedings ASCE, Journal of the Structural Division, Vol. 99, No. ST6, 1973, pp. 1091-1187
  2. Taylor, H. P. J., "Investigation of Forces Carried across Cracks in Reinforced Concrete Beams in Shear by Interlock of Aggregate," RA 42.447, Cement and Concrete Association 1970, 22 pp
  3. Sherwood, E. G., Bentz, E. C., and Collins, M. P., "Effect of Aggregate Size on Beam-Shear Strength of Thick Slabs," ACI Structural Journal, Vol. 104, No. 2, 2007, pp. 180-190
  4. Bentz, E. C., Vecchio, F. J., and Collins, M. P., "Simplified Modified Compression Field Theory for Calculating Shear Strength of Reinforced Concrete Elements," ACI Structural Journal, Vol. 103, No. 4, 2006, pp. 614-624
  5. Bazant, Z. P. and Sun, H. H., "Size Effect in Diagonal Shear Failure Influence of Aggregate Size and Stirrups," ACI Materials Journal, Vol. 84, No. 4, 1987, pp. 259-272
  6. Hanson, J. A., "Tensile Strength and Diagonal Tension Resistance of Structural Lightweight Concrete," ACI Journal Proceedings, Vol. 58, No. 7, 1961, pp. 1-37
  7. Ivey, D. l. and Buth, E., "Shear Capacity of Lightweight Concrete Beams," ACI Journal, Proceedings, Vol. 61, No. 10, 1967, pp. 634-643
  8. Ahmad, S. H., Xie, Y., and Yu, T., "Shear Strength of Reinforced Lightweight Concrete Beams of Normal and High Strength Concrete," Magazine of Concrete Research, Vol. 46, No. 166, 1994, pp. 57-66 https://doi.org/10.1680/macr.1994.46.166.57
  9. Ramirez, J. A., Olek, J., and Malone, B. J., "Shear Strength of Lightweight Reinforced Concrete Beams," ACI Special Publication, SP218-05, Vol. 218, 2004, pp. 69-89
  10. 김우석, 백승민, 이영미, 류기찬, 곽윤근, "경량 콘크리트 보의 전단내력에 관한 연구," 대한건축학회논문집, 18권, 5호, 2002, pp. 19-28
  11. 신성우, 이광수, 권영호, 오정근, "전단보강이 없는 고강도 철근콘크리트 보의 전단역학적 거동에 관한 연구," 콘크리트학회 논문집, 1권, 1호, 1989, pp. 67-74
  12. ACI Committee 318, Building Code Requirements for Structural Concrete(ACI 318-05) and Commentary(ACI 318R-05), American Concrete Institute, Farmington Hills, 2005, 436 pp
  13. 한국콘크리트학회, 콘크리트구조설계기준, 한국콘크리트학회, 2007, 327 pp
  14. Yang, K. H. and Ashour, A. F., "Load Capacity of Reinforced Concrete Continuous Deep Beams," Journal of Structural Engineering, ASCE, Vol. 134, No. 6, 2008, pp. 919-929 https://doi.org/10.1061/(ASCE)0733-9445(2008)134:6(919)
  15. Nielsen, M., Limit Analysis and Concrete Plasticity, Prentice-Hall, Inc., New Jersey, 1984, 420 pp

피인용 문헌

  1. A Fundamental Study for the Behavior of Lightweight Aggregate Concrete Slab Reinforced with GFRP Bar vol.16, pp.3, 2012, https://doi.org/10.11112/jksmi.2012.16.3.099