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Indexed by:会议论文

Date of Publication:2012-09-17

Included Journals:EI、Scopus

Abstract:A new experimental method for assessing the likelihood of cracking and cracking age of concrete was developed through using elliptical ring specimens subjected to restrained shrinkage. To explore the mechanism of this method, a numerical approach was developed to simulate stress developing and crack initiating in concrete ring. By simulating the intrinsic shrinkage effect of concrete by an externally applied fictitious thermal field which causes the same strain as the shrinkage, the internal stress and deformation of concrete and steel ring were obtained by applying the equivalent fictitious temperature load on the concrete ring specimen. Shrinkage of concrete ring specimens drying from different directions, i.e. from the top, bottom and/or outer circumferential surface, can be simulated by employing different fictitious temperature loads to the concrete ring in the restrained elliptical ring test. By comparing the behaviour of elliptical and circular ring under restrained condition, the effects of geometry on restrained shrinkage behaviour in concrete ring was discussed. The simulated results showed that the ratio between the major and minor semi-axes of elliptical ring is a major factor which affects the maximum circumferential tensile stress in concrete ring when subjected to restrained shrinkage. Elliptical ring specimens with appropriate geometry can make crack initiate earlier than in a circular ring specimen which is able to accelerate the ring tests for assessing the potential of cracking of concrete mixtures. Finally, a numerical example was presented for demonstrating the application of the proposed numerical approach for predicting the shrinkage cracking age in an elliptical concrete ring subjected to restrained shrinkage.