Evaluation of the Current AASHTO LRFD Concrete Creep Prediction Model Using South African Materials
George C FANOURAKIS
Abstract. Creep of concrete is an important design consideration. National design codes typically provide empirically based models for the estimation of creep deformation. Such models estimate a creep coefficient (ϕ), which is the ratio of the creep strain (ɛc) to the elastic strain (ɛe), which is used to predict the creep strain (c) at any age. This paper assesses the accuracy of the creep coefficients (ϕ) predicted by the latest American Association of State Highway and Transportation Officials (AASHTO), Load and Resistance Factor Design (LRFD) Bridge Design Specification. The accuracy of the AASHTO Model was evaluated by comparing the predicted with the actual (measured) creep coefficients (ϕ), on a range of concretes under laboratory-controlled conditions, for six mixes. The six mixes comprised three aggregate types (quartzite, granite and andesite) and two strength grades (water-cement ratios of 0.55 and 0.4). In the case of all six mixes, at all ages considered, the AASHTO LRFD Model underpredicted the creep coefficient (ϕ). Furthermore, the predictions were most and least accurate in the case of the quartzite and andesite concretes, respectively. In the case of all six mixes, a highly significant linear relationship (maximum P = 1.4E-11 %) was found between the predicted ϕ and actual ϕ. When considering all six mixes, an overall coefficient of variation (ωall) of 68.5 % was obtained. The results of this investigation were compared to those of 19 other models and the AASHTO LRFD Model was the 16th most accurate model of the 20 models assessed to date.
Keywords
Creep, Concrete, Codes, Coefficients, Models
Published online 4/2/2026, 10 pages
Copyright © 2026 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: George C FANOURAKIS, Evaluation of the Current AASHTO LRFD Concrete Creep Prediction Model Using South African Materials, Materials Research Proceedings, Vol. 63, pp 85-94, 2026
DOI: https://doi.org/10.21741/9781644904053-10
The article was published as article 10 of the book Advances in Cement and Concrete Research
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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