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Keywords: concrete, crack growth, fracture, discrete crack, gravity dam.

Summary

Cracks are present to some degree in all structures. It is clear now that the main difficulties in modeling cracks are the localization processes associated with the creation of cracks and their propagation. Fracture mechanics theory is the fundamental requirement of assessing the stability of such crack propagation.

To accurately predict fracture behavior, it is necessary to use finite element analysis [1,2]. A crack which is present in a loaded body can be deformed in different ways. As noted in reference [3], Irwin observed that there are three independent kinematical movements of the upper and lower crack surfaces with respect to each other and these are categorized as: the opening mode (I), the shearing mode (II) and the tearing mode (III).

Thus it will be seen that any crack deformation can be represented by the appropriate superposition of these three cases. Irwin showed that the primary stress components in the crack tip region corresponding to stress intensity factor and stress intensity factor is related to the appropriate strain energy release rate (G) and that is related to a path independent integral (J-Integral) presented by Rice [4].

For the process of crack propagation analysis in concrete structures, there are two general models: the smeared crack model and the discrete crack model [5]. In a discrete crack model, some steps should be undertaken one after another: using an initial analysis, the crack location will be found. After prediction of the crack path, the meshing will be done. Element size is related to critical energy release rate [6]. Load will be increased and the previous stress and strain will be initial conditions for new analysis and this loop continued until maximum load is determined.

In this paper a numerical program has been provided to study the behavior of a concrete gravity dam under loads. To check the accuracy of our program, the experimental test has been compared with the esults from a numerical model.

Finally to assess the accuracy, the results of our program were compared with the result of reference [7]. The comparison confirmed that the program can be used to predict crack propagation model in concrete gravity dams.

References

1: D.R.J. Owen, E. Hinton, "An Introduction to Finite Element", Pineridge Press Ltd., Swansea, U.K., 1979.
2: D.R.J. Owen, E. Hinton, "Finite Element Programming", Academic Press Inc. London Ltd., U.K., 1977.
3: D.R.J. Owen, A.J. Fawkes, "Engineering Fracture Mechanics: Numerical Methods and Applications", Pineridge Press Ltd., Swansea, U.K., 1983.
4: D.R.J. Owen, E. Hinton, "Finite Element in Plasticity", Pineridge Press Ltd., Swansea, U.K., 1983.
5: ACI Committee 446, "Finite Element Analysis of Fracture in Concrete Structures: State-of-the-Art".
6: M.T. Ahmadi, J. Amiri, "Modeling of Concrete Materials Behavior in Nonlinear Dynamic Analyses in Gravity Dams", 4th International Conference of Civil Engineering, April 1998.
7: F. Barpi, S. Valente, "Numerical Simulation of Prenotched Gravity Dam Models", Journal of Engineering Mechanics, June 2000. doi:10.1061/(ASCE)0733-9399(2000)126:6(611)

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 88 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis Paper 241 Numerical Modelling of Crack Growth in Concrete Gravity Dams Based on the Discrete Crack Method A.R. Lohrasbi¹ and R. Attarnejad² ¹Islamic Azad University, Boroujerd Branch, Iran ²School of Civil Engineering, University of Tehran, Iran doi:10.4203/ccp.88.241 purchase the full-text of this paper Full Bibliographic Reference for this paper A.R. Lohrasbi, R. Attarnejad, "Numerical Modelling of Crack Growth in Concrete Gravity Dams Based on the Discrete Crack Method", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 241, 2008. doi:10.4203/ccp.88.241 Keywords: concrete, crack growth, fracture, discrete crack, gravity dam. Summary Cracks are present to some degree in all structures. It is clear now that the main difficulties in modeling cracks are the localization processes associated with the creation of cracks and their propagation. Fracture mechanics theory is the fundamental requirement of assessing the stability of such crack propagation. To accurately predict fracture behavior, it is necessary to use finite element analysis [1,2]. A crack which is present in a loaded body can be deformed in different ways. As noted in reference [3], Irwin observed that there are three independent kinematical movements of the upper and lower crack surfaces with respect to each other and these are categorized as: the opening mode (I), the shearing mode (II) and the tearing mode (III). Thus it will be seen that any crack deformation can be represented by the appropriate superposition of these three cases. Irwin showed that the primary stress components in the crack tip region corresponding to stress intensity factor and stress intensity factor is related to the appropriate strain energy release rate (G) and that is related to a path independent integral (J-Integral) presented by Rice [4]. For the process of crack propagation analysis in concrete structures, there are two general models: the smeared crack model and the discrete crack model [5]. In a discrete crack model, some steps should be undertaken one after another: using an initial analysis, the crack location will be found. After prediction of the crack path, the meshing will be done. Element size is related to critical energy release rate [6]. Load will be increased and the previous stress and strain will be initial conditions for new analysis and this loop continued until maximum load is determined. In this paper a numerical program has been provided to study the behavior of a concrete gravity dam under loads. To check the accuracy of our program, the experimental test has been compared with the esults from a numerical model. Finally to assess the accuracy, the results of our program were compared with the result of reference [7]. The comparison confirmed that the program can be used to predict crack propagation model in concrete gravity dams. References 1 D.R.J. Owen, E. Hinton, "An Introduction to Finite Element", Pineridge Press Ltd., Swansea, U.K., 1979. 2 D.R.J. Owen, E. Hinton, "Finite Element Programming", Academic Press Inc. London Ltd., U.K., 1977. 3 D.R.J. Owen, A.J. Fawkes, "Engineering Fracture Mechanics: Numerical Methods and Applications", Pineridge Press Ltd., Swansea, U.K., 1983. 4 D.R.J. Owen, E. Hinton, "Finite Element in Plasticity", Pineridge Press Ltd., Swansea, U.K., 1983. 5 ACI Committee 446, "Finite Element Analysis of Fracture in Concrete Structures: State-of-the-Art". 6 M.T. Ahmadi, J. Amiri, "Modeling of Concrete Materials Behavior in Nonlinear Dynamic Analyses in Gravity Dams", 4th International Conference of Civil Engineering, April 1998. 7 F. Barpi, S. Valente, "Numerical Simulation of Prenotched Gravity Dam Models", Journal of Engineering Mechanics, June 2000. doi:10.1061/(ASCE)0733-9399(2000)126:6(611) purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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