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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Prestress Losses in Pretensioned Girders Part I: Method Development
Author(s): N. Al-Omaishi and M.K. Tadros
Publication: Special Publication
Appears on pages(s): 439-460
Keywords: creep; high-strength concrete; long-term materialproperties; modulus of elasticity; prestress loss; prestressedconcrete; relaxation; shrinkage; time-dependent material properties
Abstract:Prestress loss estimation is required for properly assessing concrete stresses and member deformation. Earlier methods of prestress loss prediction were based on relatively low concrete strength. Their use for high strength concrete can produce significant errors due to their inability to accommodate varying material properties. Another source of error for earlier methods is that they do not adequately address the interaction between precast concrete members and cast-in-place composite topping. This paper presents the results of the research work conducted by Tadros et al.1 in the National Cooperative Highway Research Program (NCHRP) 18-07 study on prestress losses in high strength concrete which have been adopted by the American Association of State Highway and Transportation Officials, Load and Resistance Factor Design, AASHTO LRFD Specifications2 for inclusion in the 2005 Edition. This paper consists of two parts. Part I describes the development of the new methods that are applicable to conventional and high strength concrete ranging from 4 to 15 ksi (28 to 103 MPa). Part II deals with the experimental program and comparison of measured versus estimated prestress losses.
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