Conventional Models for Shrinkage of Concrete
[1]
Janusz Hołowaty, Faculty of Civil Engineering and Architecture, West Pomeranian University of Technology, Szczecin, Poland.
Models for shrinkage in cement concrete are generally used to express volume changes in concrete without external loads. Shrinkage models which are calibrated for ordinary normal strength concrete with Portland cements are presented and compared. They were developed using many years’ theoretical and experimental research works which tried to follow the development of concrete technology and allow for better estimation of this phenomenon. Estimation of shrinkage strains according to ACI 209, B3, Eurocode 2 models is outlined. For practical application the latest model (Eurocode 2) is adjusted for initial parameters available at the design stage. Comparison of development over time and final values of shrinkage strain for different models indicate that the calculated results may differ significantly. Correct calculation of shrinkage strains in concrete structures sensitive to time-dependent deformations is still very difficult and sometimes requires individually calibrated models. Due to advances in concrete mixes and types of cements, newly developed models usually estimate higher values of final shrinkage in ordinary concrete than the previously used models. Adoption of proper magnitude of shrinkage strains in concrete structures is necessary for their durability and economic design.
Shrinkage of Concrete, Shrinkage Models, Time Dependent Properties
[1]
Ghali, A., Favre, R., Elbadry, M., Concrete Structures: Stresses and Deformations: Analysis and Design for Serviceability, Spon Press, London and New York, 2012.
[2]
Gilbert, R. I., Ranzi, G., Time-Dependent Behavior of Concrete Structures, Spon Press, London and New York, 2011.
[3]
Bažant, Z. P., Li, G. H., Yu, Q., Prediction of creep and shrinkage and their effects in concrete structures: Critical appraisal, Eighth International Conference on Creep, Shrinkage and Durability Mechanics of Concrete and Concrete Structures (Concreep-8). Taylor & Francis Group, London, 2009.
[4]
ACI 209.2 R-08, Guide for Modeling and Calculating Shrinkage and Creep in Hardened Concrete, ACI Manual of Concrete Practice, 2009.
[5]
Bažant Z. P., Baweja S., Creep and shrinkage prediction model for analysis and design of concrete structures – model B3. RILEM draft recommendation. Materials and Structures, 1995.
[6]
ACI 209R-92, Prediction of Creep, Shrinkage, and Temperature Effects in Concrete Structures, ACI Manual of Concrete Practice, 2008.
[7]
CEB-FIB Model Code 1990. Design Code, Thomas Telford. London, 1993.
[8]
EN 1992-1-1: 2004. Eurocode 2: Design of concrete structures. Part 1-1: General rules for buildings.
[9]
EN 1992-2: 2008. Eurocode 2: Design of concrete structures. Part 2: Concrete bridges. Design and detailing rules.
[10]
Nawy E. G., Concrete Construction Engineering Handbook, CRC Press, London and New York, 2008.
[11]
Hołowaty, J., Creep and Shrinkage of Concrete in Eurocode 2 and Polish Bridge Standards—Necessity for Implementation, Journal of Civil Engineering and Architecture, Vol. 9, No. 4, 2015, pp. 460-6.
[12]
Hołowaty, J., Creep in cement concrete in conventional models, The 8th International Conference, AMCM 2014, Analytical Models and New Concepts in Concrete and Masonry Structures, Wrocław, 2014, pp. 140-1.
[13]
fib Model Code for Concrete Structures 2010, Ernest & Sohn, Berlin, 2013.
[14]
Müller, H. S., Anders, I., Breiner, R., Vogel, M., Concrete: treatment of types and properties in fib Model Code 2010, Journal of the fib - Structural Concrete, Vol. 14, No. 4, 2013.
[15]
Hołowaty, J., Contemporary models for shrinkage in cement concrete, The 10th Central European Congress on Concrete Engineering, CCC 2014, Concrete Offers for Period of Economic Recovery, Liberec, 2014, pp. 34-35.
[16]
Hołowaty, J., Shrinkage model for normal - and high-strength concrete in fib Model Code 2010, The 11th Central European Congress on Concrete Engineering, CCC 2015, Innovative Concrete Technology in Practice, Hainburg, 2015, in print.
