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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 108
Edited by: J. Kruis, Y. Tsompanakis and B.H.V. Topping
Paper 17

Estimating the Degree of Restraint in a Restrained Elliptical Ring Test

W. Dong1, X.M. Zhou1,2 and Z.M. Wu1

1State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, P. R. China
2Department of Mechanical, Aerospace and Civil Engineering, Brunel University, London, United Kingdom

Full Bibliographic Reference for this paper
W. Dong, X.M. Zhou, Z.M. Wu, "Estimating the Degree of Restraint in a Restrained Elliptical Ring Test", in J. Kruis, Y. Tsompanakis, B.H.V. Topping, (Editors), "Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 17, 2015. doi:10.4203/ccp.108.17
Keywords: ring test, restraint shrinkage, elliptical ring, cracking, degree of restraint, numerical simulation, finite element, ANSYS.

The restrained circular ring test, which is recommended by AASHTO PP 34-89 and ASTM C1581/C1581M-09a, has been used to assess the potential of cracking of concrete and other cement-based materials during the early ages of construction. Recently, a novel elliptical ring test method was proposed to replace the circular ring test method for the purpose of shortening the test duration and more conveniently examining crack evolution in concrete rings. To explore the mechanism of this new method, a numerical model was developed to analyse stress development and crack initiation in concrete ring specimens in which the effect of concrete shrinkage was simulated by a fictitious temperature field externally applied to the concrete causing the same strain as shrinkage. Through comparing the displacements caused by free shrinkage in a concrete ring and the actual displacement of the concrete subject to restraint from the internal steel ring, the degree of restraint from the internal steel ring on the surrounding concrete can be determined. Using the proposed numerical method, it is possible to evaluate the effects of ring geometry and restraining steel ring wall thickness on the degree of restraint. It is found that the elliptical steel ring with appropriate geometry can provide a much higher degree of restraint to the surrounding concrete and enable crack initiation much earlier than with the circular ring, which is able to accelerate the ring test for assessing the potential of cracking of concrete mixtures.

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