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Journal of the South African Institution of Civil Engineering

versión On-line ISSN 2309-8775
versión impresa ISSN 1021-2019

J. S. Afr. Inst. Civ. Eng. vol.50 no.1 Midrand mar. 2008

 

TECHNICAL PAPER

 

Finite element fracture modelling of concrete gravity dams

 

 

Q Cai; J M Robberts; B W J van Rensburg

 

Correspondence

 

 


ABSTRACT

A smeared crack model, based on non-linear fracture mechanics, was developed which allows for either linear or bilinear softening and assumes shear retention dependent on the strain normal to a crack. A mesh objectivity verification study proves that the proposed crack modelling method is mesh objective. The crack model and its computational procedure is verified for a benchmark concrete gravity dam model and an existing concrete gravity dam by comparing the results with those of numerical investigations obtained by other researchers. Furthermore, an existing concrete gravity dam in South Africa is analysed and evaluated with regard to dam safety in terms of the maximum overflow level. A higher imminent failure flood is predicted in the analysis than that obtained by classical strength-based methods. The study proves the usefulness and applicability of the proposed crack model and implementation procedure in predicting crack response and evaluating the safety of concrete gravity dams. A sensitivity study on the material fracture properties and fracture parameters is included for the purpose of investigating the uncertainties often encountered in this type of analysis. The influence of the fracture properties and parameters on the cracking response and the overall structural behaviour is discussed.


 

 

Full text available only in PDF format.

 

 

ACKNOWLEDGEMENTS

The Department of Water Affairs and Forestry (DWAF) is thanked for permission to publish this paper. The views expressed are those of the authors and not necessarily of the DWAF.

 

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Correspondence:
Qingbo Cai
759 Lorna Street,
Moreleta Park Ext 10
Pretoria, 0044
T 012-336-8096 (w)
C 082-869-8323
DBE@dwaf.gov.za

John Robberts
Nuclear Structural Engineering (Pty) Ltd
Balblair Building
Kildrummy Office Park,
Cnr Witkoppen Road & Umhlanga Road
Paulshof, Johannesburg
T 012-319-7256
C 082-784-8743
john.robberts@nucse.com

Ben Van Rensburg
Department of Civil Engineering
University of Pretoria
Pretoria, 0002
T 012-420-2439
ben.vanrensburg@up.ac.za

 

 

 

 

JOHN ROBBERTS was associated with the Department of Civil Engineering of the University of Pretoria at the time this paper was produced. John Robberts obtained his BEng (Civil) in 1986 from the University of Pretoria and then joined this institution as lecturer in Structural Engineering. He obtained his MEng (Structural Engineering) from the University of Pretoria, and his PhD from Imperial College London. John also worked at the Atkins bridge office in Epsom (UK) and PBMR (Pretoria). John is currently a director of Nuclear Structural Engineering (Pty) Ltd. He remains involved with the University of Pretoria, as a part-time lecturer, supervising research students and presenting postgraduate courses in Reinforced and Prestressed Concrete.

 

 

QINGBO CAI was associated with the Department of Civil Engineering of the University of Pretoria at the time this paper was produced. He is a deputy chief engineer in Directorate: Options Analysis at Department of Water Affairs and Forestry. He obtained his BEng (Civil) from the Southwest Jiao-Tong University n the People's Republic of China, an MSc (Structural Engineering) from the Northern Jiao-Tong University in the People's Republic of China, and a PhD from the University of Pretoria. Over the last 20 years, he has been involved in structural design of various buildings and research on railway prestressed concrete poles and sleepers, and advanced finite element analysis of civil and mechanical structures such as dams and pipes.

 

 

BEN VAN RENSBURG is a professor in the in the Department of Civil Engineering at the University of Pretoria where he teaches and does research in structural engineering. He started his career in consulting engineering, worked in a research organization, and subsequently joined the University of Pretoria. de obtained BSc and MSc degrees in CM Engineering from the University of Pretoria, an MSc (Structural Engineering) from the University of Southampton and a PhD (Civil Engineering) from the University of Pretoria.

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