Evaluation of the creep coefficients of international concrete creep prediction models

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Abstract

Creep of concrete is an important design consideration. National design codes therefore provide empirically based models for the estimation of creep deformation. Such models estimate a creep coefficient (φ) and an elastic modulus (E) of the concrete, both of which are used to predict the creep strain at any age. This paper assesses the accuracy of the creep coefficients (φ) predicted by fourteen “design code-type" models, with a view to ascertain whether the estimated φ or E is responsible for the inaccuracy of some of the models. The models considered are those contained in SANS 10100 (2000)/BS 8110 (1985), SANS 10100 (2000) Modified, ACI 209 (1992), AS 3600 (2001 & 2009), CEB-FIP (1970, 1978 & 1990), the Eurocode EC (2004), Gardener and Lockman (2000 & 2004), Gardener and Zhao (1993) and the RILEM B3 (1995) methods. Laboratory creep tests were conducted on concrete prisms covering a range of mixes. The measured φ values were statistically compared to those predicted by the models considered. The results indicated that, for the range of concretes tested, the CEB-FIP (1990) method yielded the most accurate predictions of creep coefficient, giving the lowest overall coefficient of variation (ωall) of 27,7%. The least accurate method was the CEB-FIP (1978) which yielded an overall coefficient of variation (ωall) of 112,5%. Furthermore, the accuracy of the predicted φ values correlated highly significantly (P = 0,001%) with the accuracy of the predicted creep magnitudes. The results of this investigation led to recommending the SANS 10100 (2000)/ BS 8110 (1985) model for predicting creep coefficients for South African conditions.

Original languageEnglish
Title of host publicationFib Symposium 2016
Subtitle of host publicationPerformance-Based Approaches for Concrete Structures, Proceedings
EditorsHans Beushausen
Publisherfib. The International Federation for Structural Concrete
Pages1-10
Number of pages10
ISBN (Print)9782883941229
Publication statusPublished - 2016
EventInternational fib Symposium on Performance-Based Approaches for Concrete Structures, 2016 - Cape Town, South Africa
Duration: 21 Nov 201623 Nov 2016

Publication series

Namefib Symposium
ISSN (Print)2617-4820

Conference

ConferenceInternational fib Symposium on Performance-Based Approaches for Concrete Structures, 2016
Country/TerritorySouth Africa
CityCape Town
Period21/11/1623/11/16

Keywords

  • Concrete
  • Creep
  • Elastic modulus
  • Models

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Materials Science (miscellaneous)

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