时间：2014年12月22日（星期一）上午11点
地点：安中大楼A326
Title: A New Method for Assessment of Cracking Tendency of Concrete: Experimental and Numerical
Speaker: Dr Xiangming Zhou (周向明)
Senior Lecturer in Civil Engineering Design
Brunel University London
Abstract: In this talk, a new test method for assessing cracking tendency of concrete and other cement-based materials will be introduced. The new method adopts elliptical ring geometry to replace the conventional circular ring geometry recommended by American Association of State Highway and Transportation Officials (AASHTO) and ASTM with AASHTO adopting thick rings and ASTM thin rings. A series of concrete rings, circular and elliptical, thin and thick, have been tested till crack propagating through concrete ring wall to investigate the effects of ring geometry on cracking age, crack pattern and cracking characteristics in restrained concrete rings. A fracture mechanics-based numerical model is also established to simulate stress development and crack initiation/propagation in restrained concrete rings. Cracking age and position of a series of circular and elliptical, thin and thick rings are obtained from numerical analyses which agree reasonably well with experimental results. Besides, it is found that the failure mechanism of concrete rings changed with the increase of concrete ring wall thickness. In thin rings, crack initiation is mainly caused by restraining effect from the central steel ring so that an appropriate elliptical shape can accelerate cracking process as desirable for practical purpose. While in thick rings, crack initiation is mainly due to the self-restraint effect from concrete itself caused by non-uniform circumferential drying. So an elliptical geometry does not necessarily increase stress concentration in thick rings leading to earlier cracking than in thick circular rings. Finally a recommendation to AASHTO thick ring test method has been made in order to serve the designated purpose of assessing cracking tendency of concrete under restrained shrinkage.
Bio: Dr Zhou is a Senior Lecturer in Civil Engineering Design at Department of Mechanical, Aerospace and Civil Engineering, at Brunel University London, UK. Prior to joining Brunel in October 2008, he was a lecturer and then senior lecturer at University of Greenwich, UK. Before moving to the UK, he did post-doctoral research at Hong Kong Polytechnic University and Hong Kong University of Science and Technology, respectively. He received his BEng in Civil & Structural Engineering and MEng in Structural Engineering both from Tongji University, and his PhD in Civil Engineering from Hong Kong University of Science and Technology. His research covers a board range of topics in construction materials and structural engineering. In the area of Construction Materials, he focuses on low carbon and energy efficient cementitious / cementless materials such as magnesium oxychloride (MOC) cement and geopolymer concrete; advanced concrete technology such as extrusion, testing and modelling of rheology, extrusion and early-age engineering properties of concrete and other cement-based materials; elliptical ring test and modelling of concrete subject to restrained shrinkage; fracture and impact properties of natural fibre reinforced concrete etc. In Structural Engineering, his research covers seismic testing, analysis and design of steel-concrete composite high-rise building, performance-based multi-hazards mitigation of building structures under extreme loadings, precast concrete segmental bridges, and multi-scales modelling of mechanics and structural behaviour of concrete which brings his expertise in construction materials and structural engineering under one umbrella. His recent research interests extend to nanotechnology and graphene in concrete materials. He has been Principal Investigator of research projects funded by UK Engineering and Physical Science Research Council, European Commission 7th Framework Programme, European Commission Horizon2020, UK Royal Academy of Engineering etc. Among which, he has been Scientific Manager of a 3.8 million-euro 7th Framework Programme project on nanotechnology enhanced cement-based materials. He has authored/co-authored 90 technical papers in conferences and journals such as Journal of Materials in Civil Engineering ASCE, Journal of Engineering Mechanics, ASCE, Journal of Bridge Engineering ASCE, ACI Structural Journal, ACI Materials Journal, Cement & Concrete Research, Cement & Concrete Composites, Construction and Building Materials, Engineering Structures, Engineering Fracture Mechanics, RILEM Materials and Structures, Journal of Earthquake Engineering, Smart Materials and Structures etc. He received the 1st class Natural Sciences Award by Ministry of Education, China in 2006.
欢迎广大师生踊跃参加！
建筑工程学院
2014年12月19日
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