Comparative Study of Prestress Losses
This paper compares the prestress losses as calculated by four different design codes; British standard CP110, Comite Europeen du Beton 70 and 78, American Concrete Institute 77 and the Prestressed Concrete Institute method (PCI). The comparison is done by determining the total losses which take place in a rectangular prestressed concrete beam for both pre-tensioning and post-tensioning systems. The results show that total losses calculated for the post-tensioning method are higher than those calculated for the pre-tensioning method, which is not the usual case. It seems that the PCI method may be required for special structures or for simply supported slender members which may be sensitive to small changes in deflections. However, for non-special structures, or where actual losses have little effect on the design, it is better to compute losses by the ACI method because it is simple and does take into considerations interactions between the various sources of losses. However, it is not possible to conclude which method gives the more accurate prediction of shrinkage and creep without direct co-relation to realistic insitu data.
R. I. Gilbert, N. C. Mickleborough, G. Ranzi, Design of prestressed concrete to AS 3600-2009, CRC Press, 2016
J. J. Brooks, “30-year creep and shrinkage of oncrete”, Magazine of Concrete Research, Vol. 57, No. 9, pp. 545–556, 2005
A. M. Neville, W. H. Dilger, J. J. Brooks, “Creep of plain and structural concrete”, Construction Press, London, pp. 361, 1984
J. J. Brooks, P. J. Wainwright, M. boukendakdji, “Influences of slag type and replacement level on strength, elasticity, shrinkage and creep of concrete”, 4th Inter. Conf. on the use of Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Vol 2, Istanbul, Turkey, ACI Spec. Publ., pp 1325-1341, 1992
ACI Committee 209, “Guide for modeling and calculating shrinkage and creep in hardened concrete”, ACI Report 209.2R-08, Farmington Hills, 2008
CEB-FIP Model Code “Model code for concrete structures”, Thomas Telford Services Ltd., London, Great Britain; also published by Comité euro-international du béton (CEB), Bulletins d'Information No. 213 and 214, Lausanne, Switzerland, 1990
Z. P. Bazant, Q. Yu, “Excessive long-time deflections of prestressed box girders”, ASCE J. of Structural Eng., Vol. 138, No. 6, pp. 676-696, 2012
K. Jayakumar, A. Upadhyay, N. M. N. Bhandari, “Artificial neural network for predicting creep and shrinkage of concrete”, Journal of Advanced Concrete Technology, Vol. 6, No. 1, pp.135-142, 2008
CP110, The Structural Use of Concrete- Part 1, Britsih Standard Code of Practice ,1972
CEB-FIP, International recommendations for the design and construction of concrete structures principles recommendations, European Concrete Committee , 1970
CEB-FIP, Model code for concrete structures, Comitee European du Beton, Fedeation Internationale de la Precontraite, Paris, 1978
ACI Committee 318, Building code requirements for reinforced concrete (ACI 318-77), American Concret Institute, Detroit, 1977
PCI Committee on Prestress Losses, “Recommendations for estimating prestress losses”, Prestressed Concrete Institute Journal, Vol. 20, No. 4, pp. 43-75, 1975
F. M. Abdellatif, Long-term prediction of deformation of plain concrete, MSc Thesis, Department of Civil Engineering, Leeds University, 1982
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