Title:
Shored/Reshored Construction of Flat Plates
Author(s):
Luc Monette and N.J. Gardner
Publication:
Concrete International
Volume:
37
Issue:
9
Appears on pages(s):
25-32
Keywords:
deflection, punching shear, construction, form
DOI:
10.14359/51688154
Date:
9/1/2015
Abstract:
Flat plates are usually constructed using a single level of shores (forms) supporting the freshly placed concrete. Shored construction accumulates load to the lowest (oldest) plate in the shored sequence, while shored/reshored construction applies the load to the upper (youngest) plate in the system. Historical shoring analyses are reviewed and the results of a parametric analysis of the effect of reshore stiffness are presented. Based on the analyses, factors are provided for calculation of the required strength of supporting flat plates in buildings constructed using a single level of shores and multiple levels of elastic reshores.
Related References:
1. Feld, J., “Reshoring of Concrete Buildings,” Engineering News Record, Oct. 1966, pp. 33-34.
2. Nielsen, K.E.C., “Loads on Reinforced Concrete Floor Slabs and Their Deformations During Construction,” Proceedings No. 15, Swedish Cement and Concrete Institute, Royal Institute of Technology, Stockholm, Sweden, 1952, 116 pp.
3. Grundy, P., and Kabaila, A., “Construction Loads on Slabs with Shored Formwork in Multistory Buildings,” ACI Journal Proceedings, V. 60, No. 12, Dec. 1963, pp. 1729-1738.
4. Agarwal, R.K., and Gardner, N.J., “Form and Shore Requirements for Multistory Flat Slab Type Buildings,” ACI Journal Proceedings, V. 71, No. 11, Nov. 1974, pp. 559-569.
5. Liu, X.L.; Chen, W.F.; and Bowman, M.D., “Construction Load Analysis for Concrete Structures,” Journal of Structural Engineering, ASCE, V. 111, No. 5, May 1985, pp. 1019-1036.
6. Liu, X.L.; Chen, W.F.; and Bowman, M.D., “Shore-Slab Interaction in Concrete Buildings,” Journal of Construction Engineering and Management, V. 112, No. 2, June 1986, pp. 227-244.
7. Liu, X.L., and Chen, W.F., “Probability Distribution of Maximum Wooden Shore Loads in Multistory R.C. Buildings,” Structural Safety, V. 4, No. 3, 1987, pp. 197-215.
8. Stivaros, P.C., and Halvorsen, G.T., “Shoring/Reshoring Operations for Multistory Buildings,” ACI Structural Journal, V. 87, No. 5, Sep.-Oct. 1990, pp. 589-596.
9. Stivaros, P.C., and Halvorsen, G.T., “Equivalent Frame Analysis of Concrete Buildings during Construction,” Concrete International, V. 13, No. 8, Aug. 1991, pp. 57-62.
10. Beeby, A.W., “Task 4: Early Striking of Formwork and Forces in Backprops,” Report 394, Building Research Establishment, UK, 2000.
11. De Almeida Prado, J.F.M.; Silva Corrêa, M.R.; and Ramalho, M.A., “A New Procedure for the Analysis of Construction Loads in Multistory Reinforced Concrete Structures,” Structural Design of Tall and Special Buildings, V. 12, No. 4, Dec. 2003, pp. 293-315.
12. Puente, I.; Azkune, M.; and Insausti, A., “Shore-Slab Interaction in Multistory Reinforced Concrete Buildings during Construction: An ExperiMental Approach” Engineering Structures, V. 29, No. 5, 2007, pp. 731-741.
13. LUSAS Civil & Structural Software, LUSAS, Forge House, 66 High Street, Kingston upon Thames, Surrey, KT1 1HN, UK. (www.lusas.com)
14. CSA-A.23.3-04, “Design of Concrete Structures,” Canadian Standards Association, Toronto, ON, Canada, 2004, 258 pp.
15. ACI Committee 347, “Guide for Shoring/Reshoring of Concrete Multistory Buildings (ACI 347.2R-05),” American Concrete Institute, Farmington Hills, MI, 2005, 18 pp.