Journal of the Korea institute for structural maintenance and inspection (한국구조물진단유지관리공학회 논문집)

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
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Analysis of Effects of Reshoring Works on Short and Long Term Deflections of Flat Plates

플랫 플레이트 구조의 장단기 처짐 제어에 대한 동바리 재설치 작업의 효과 분석

  • Received : 2016.09.01
  • Accepted : 2016.10.04
  • Published : 2017.01.01
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Abstract

RC flat plates may be governed by a serviceability as well as a strength condition, and a construction sequence and its impact on the distributions of gravity loads among slabs tied by shores are decisive factors influencing short and long term behaviors of flat plate. Over-loading and tensile cracking in early-aged slabs significantly increase the deflection of a flat plate system under construction, and a reshoring work may be helpful in reducing slab deflections by controlling the vertical distributions of loads in a multi-shored flat plate system. In this study, a effect of reshoring works on short and long term deflections of flat plate systems are analyzed. The slab construction loads with various reshoring schemes and slab design and construction conditions are defined by a simplified method, and the practical calculation of slab deflections with considering construction sequences and concrete cracking and long term effects is applied. From parametric studies, the reshoring works are verified to reduce slab deflections, and the optimized conditions for the reshoring works and slab design and constructions are discussed.

RC 무량판 구조는 강도 뿐만 아니라 사용성 조건에 지배받을 수 있으며, 시공 과정 및 이에 따른 동바리로 연결된 슬래브들 간의 중력하중의 분포가 무량판의 장단기 거동에 영향을 주는 중요한 요소로 작용할 수 있다. 조기재령 슬래브에 과하중이 작용하여 균열이 발생하는 경우 시공 과정에서 무량판 구조의 처짐이 크게 증가할 수 있으므로, 동바리 재설치를 통해 다층지지 슬래브에서 하중의 수직 분포를 조절하는 것은 처짐을 감소시키는 데 도움이 될 수 있다. 이 연구에서는 무령판 구조의 장단기 처짐에 대한 동바리 재설치 작업의 영향을 분석한다. 다양한 동바리 재설치 조건과 슬래브 설계 및 시공 조건에 따른 슬래브 시공하중이 간편법에 의하여 정의되고, 시공 과정과 콘크리트의 균열 및 장기 효과를 고려한 슬래브 처짐 실용해석법을 통해 장단기 처짐이 산정된다. 변수연구를 통하여 동바리 재설치 작업의 슬래브 처짐 저감효과를 검증하며, 슬래브 처짐을 위한 동바리 시공과 슬래브 설계 및 시공에 대한 최적 조건을 분석한다.

Keywords

References

  1. ACI Committe 318 (2011), Building Code Requirements for Structural Concrete (ACI 318-11), American Concrete Institute, Farmington Hills, MI, USA, 473.
  2. ACI Committee 347 (2005), Guide for shoring/Reshoring of Concrete Multistory Buildings (ACI 347.2R-05), American Concrete Institute, Farmington Hills, MI, USA, 3-7.
  3. AIK (2013), Standard Specifications for Building Construction, Architectural Institute of Korea, Seoul, 58-70.
  4. Choe, M. M., Choi, S. M., Eom, T. S., and Kim, J. Y. (2012), An Analysis on Short and Long-Term Deflections of Flat Plates Considering Construction and Design Conditions, Journal of Architectural Institute of Korea (Structure), 28(8), 69-77.
  5. Choi, S. M., Eom, T. S., and Kim, J. Y. (2012), Parametric Study on Long-Term Deflections of Flat Plates Considering Effects of Construction Loads and Cracking, Journal of Korea Institute for Structural Maintenance and Inspection, 16(1), 44-54. https://doi.org/10.11112/jksmi.2012.16.1.044
  6. Chun, S. C., Tak, S. Y., Lee, S. H., Sho, K. H., and Ha, T. H. (2014), Evaluation of Construction Loads of Slabs and Shores with Removing Shores and Placing Reshores, Journal of the Korea Concrete Institute, 26(3), 385-392. https://doi.org/10.4334/JKCI.2014.26.3.385
  7. Gardner, N. J. and Fu, H. C. (1987), Effects of High Construction Loads on the Long-Term Deflections of Flats Slabs, ACI Structural Journal, 84(3), 349-360.
  8. Grundy, P. and Kabaila, A. (1963), Construction Loads on Slab with Shored Formwork in Multistory Building, ACI Journal, 60(12), 1729-1738.
  9. Hwang, H. J., Park, H. G., Hong, G. H., Im, J. H., and Kim, J. Y. (2010), Effects of Shore Stiffness and Concrete Cracking on Slab Construction Load I: Theory, Journal of the Korea Concrete Institute, 22(1), 41-50. https://doi.org/10.4334/JKCI.2010.22.1.041
  10. Kang, S. H., Choi, K. K., and Park, H. G. (2003), Minimum Thickness Requirements of Flat Plate Affected by Construction Load, Journal of the Korea Concrete Institute, 15(5), 650-661. https://doi.org/10.4334/JKCI.2003.15.5.650
  11. Kang, S. M., Eom, T. S., and Kim, J. Y. (2013), Reshoring effects on deflections of multi-shored flat plate systems under construction, Structural Engineering and Mechanics, 45(4), 455-470. https://doi.org/10.12989/sem.2013.45.4.455
  12. KCI (2012), Concrete Structure Code, Korea Concrete Institute, Seoul, 523.
  13. Kim, J. Y. (2009), Applications of Practical Analysis Scheme for Evaluating Effects of Over-Loads during Construction on Deflections of Flat Plate System, Journal of Computational Structural Engineering Institute of Korea, 22(1), 25-34.
  14. Kim, J. Y., Im, J. H., and Park, H. G. (2009), Calculations of Flat Plate Deflections Considering Effects of Construction Loads and Cracking, Journal of the Korea Concrete Institute, 21(6), 797-804. https://doi.org/10.4334/JKCI.2009.21.6.797
  15. Vollum, R. L., Moss, R. M., and Hossain, T. R. (2002), Slab Deflction in the Cardington In-Situ Concrete Frame Building, Magazine of Concrete Research, 54(1), 23-34. https://doi.org/10.1680/macr.2002.54.1.23