TY - GEN
T1 - Evaluation of the creep coefficients of international concrete creep prediction models
AU - Fanourakis, George C.
N1 - Publisher Copyright:
© fédération internationale du béton (fib).
PY - 2016
Y1 - 2016
N2 - 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.
AB - 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.
KW - Concrete
KW - Creep
KW - Elastic modulus
KW - Models
UR - http://www.scopus.com/inward/record.url?scp=85134803132&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:85134803132
SN - 9782883941229
T3 - fib Symposium
SP - 1
EP - 10
BT - Fib Symposium 2016
A2 - Beushausen, Hans
PB - fib. The International Federation for Structural Concrete
T2 - International fib Symposium on Performance-Based Approaches for Concrete Structures, 2016
Y2 - 21 November 2016 through 23 November 2016
ER -