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Reshoring effects on deflections of multi-shored flat plate systems under construction

  • Kang, Su-Min (Technology Research Institute, Daelim Industrial Co.) ;
  • Eom, Tae-Sung (Department of Architecture, Catholic University of Daegu) ;
  • Kim, Jae-Yo (Department of Architectural Engineering, Kwangwoon University)
  • Received : 2011.05.10
  • Accepted : 2013.01.06
  • Published : 2013.02.25

Abstract

RC flat plates that have no flexural stiffness by boundary beams may be governed by a serviceability as well as a strength condition. A construction sequence and its impact on the distributions of construction loads among slabs tied by shores are decisive factors influencing immediate and long term performances of flat plate. Over-loading and tensile cracking in early-aged slabs significantly increase the deflection of a flat plate system under construction. A reshoring work may be helpful in reducing slab deflections by controlling the vertical distributions of construction loads in a multi-shored flat plate system. In this study, a change of construction loads by reshoring works and its effects on deflections of flat plate systems under construction are analyzed. The slab construction loads with various reshoring schemes are defined by a simplified method, and the practical calculation of slab deflections with considering construction sequences and concrete cracking effects is applied. From parametric studies, the reshoring works are verified to reduce construction loads and slab deflections.

Keywords

References

  1. ACI Committee 209 (1997), Prediction of creep, shrinkage, and temperature effects in concrete structures (ACI 209R-92), American Concrete Institute, Farmington Hills, MI, USA.
  2. ACI Committee 318 (2008), Building code requirement for structural concrete (ACI 318-08), American Concrete Institute, Farmington Hills, MI, USA.
  3. ACI Committee 347 (2005), Guide for shoring/reshoring of concrete multistory buildings (ACI 347.2R-05), American Concrete Institute, Farmington Hills, MI, USA.
  4. ACI Committee 435 (2003), Control of deflection in concrete structures (ACI 435R-95), American Concrete Institute, Farmington Hills, MI, USA.
  5. Bischoff, P.H. and Scanlon, A. (2007), "Effective moment of inertia for calculating deflections of concrete members containing steel reinforcement and fiber-reinforced polymer reinforcement", ACI Structural Journal, 104(8), 68-75.
  6. Chao, S.H.,and Naaman, A.E. (2006), "Simplified calculation of short-term deflection in prestressed twoway flat slabs", ACI Structural Journal, 103(6), 850-856.
  7. El-Shahhat, A.M. and Chen, W.F. (1992), "Improved analysis of shore-slab interaction", ACI Structural Journal, 89(5), 528-537.
  8. Gardner, N.J. and Fu, H.C. (1987), "Effects of high construction loads on the long-term deflections of flat slabs", ACI Structural Journal, 84(3), 349-360.
  9. Grundy, P. and Kabaila, A. (1963), "Construction loads on slabs with shored formwork in multistory buildings", ACI Journal, 60(12), 1729-1738.
  10. Hossain, T.R. and Vollum, R.L. (2002), "Prediction of slab deflection and validation against Cardington data", Proceedings of the Institution of Civil Engineers. Structures and Buildings, 152(3), 235-247. https://doi.org/10.1680/stbu.2002.152.3.235
  11. Kim, J.Y. and Abdelrazaq, A.K. (2009), "Construction sequence analysis of the flat plate system in a highrise building and its impact on the construction cycle", Structural Design of Tall and Special Buildings, 18(3), 341-350. https://doi.org/10.1002/tal.443
  12. Kim, J.Y., Im, J.H. and Park, H.G. (2009), "Calculation of flat plate deflections considering effects of construction loads and cracking", Journal of the Korea Concrete Institute, 21(6), 797-804. (in Korean) https://doi.org/10.4334/JKCI.2009.21.6.797
  13. Lee, J.I., Scanlon, A. and Scanlon, M.A. (2007), "Effect of early age loading on time-dependent deflection and shrinkage restraint cracking of slabs with low reinforcement ratios", ACI Special Publication, 246, 49-166.
  14. Liu, X., Chen, W.F. and Bowman M.D. (1985), "Construction load analysis for concrete structures", Journal of Structural Engineering, ASCE, 111(5), 1019-1036. https://doi.org/10.1061/(ASCE)0733-9445(1985)111:5(1019)
  15. Ofosu-Asamoah, K. and Gardner, N.J. (1997), "Flat slab thickness required to satisfy serviceability including early age construction load", ACI Structural Journal, 94(6), 700-707.
  16. Puente, I., Azkune, M. and Insausti, A. (2007), "Shore-slab interaction in multistory reinforced concrete building during construction: An experimental approach", Engineering Structures, 29(5), 731-741. https://doi.org/10.1016/j.engstruct.2006.06.018
  17. Rangan, B.V. (1976), "Prediction of long-term deflections of flat plates and slabs". ACI Journal, 73(4), 223-226.
  18. Scanlon, A. and Murray, D.W. (1982), "Practical calculation of two-way slab deflections", Concrete International, 43-50.
  19. Vollum, R.L. and Afshar, A. (2009), "Influence of construction loading on deflections in reinforced concrete slabs", Magazine of Concrete Research, 61(1), 3-14. https://doi.org/10.1680/macr.2009.61.1.3

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