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Keywords: arch dam, earthquake loading, optimal design, hydrodynamic effects, simultaneous perturbation stochastic approximation.

Summary

An efficient method is presented for shape optimization of arch dams. A finite element model is presented based on linear dynamic behavior of arch dam-water system. Interaction between dam and the foundation rock is not considered and it is assumed to be rigid to avoid the extra complexities that would otherwise arise. Interaction between the fluid and foundation rock is approximately considered thorough a damping boundary condition applied along the bottom and sides of the reservoir. The finite element model involved is compared with exact solutions, reported in literature, and computational performance of the model is verified.

The optimization is carried out using simultaneous perturbation stochastic approximation (SPSA) method [1]. This method requires only two measurements of the objective function regardless of dimension of the optimization problem in each cycle of the optimization process. This feature allows for a significant reduction in computational cost, especially for problems with a large number of variables.

The load cases included here are gravity load, hydrostatic and hydrodynamic pressure and seismic loading. The seismic load for earthquake records is applied in the upstream-downstream direction of the dam. Time history analysis is also performed using full transient dynamic analysis based on Newmark's method. The design variables are the shape parameters of arch dam and the concrete volume of dam body is considered as an objective function. Design constraints are divided into some groups including the behavior, geometric and stability constraints. The behavior constraints are defined to prevent the failure of each element of the arch dam with a specified safety factor for the earthquake duration. A simple method is also employed to treat time history constraints [2]. In order to ensure the sliding stability of the arch dam, the central angles of the dam is restricted to its critical values. The most important geometric constrains are those that prevent intersection of upstream and downstream faces.

In order to assess the effectiveness of proposed method and examine the water effects on the arch dam design optimization, a large arch dam example is investigated. It is observed that fluid-structure interaction has an important role in the design of arch dams and neglecting the water effects on arch dam design will lead to an impractical design. It is also found that the optimization process can efficiently reduce the concrete volume.

References

1: J.C. Spall, "Introduction to Stochastic Search and Optimization: Estimation, Simulation and Control", John Wiley and Sons, Inc., 2003. doi:10.1002/0471722138
2: J.C. Arora, "Optimization of structures subjected to dynamic loads", In: C.T. Leondes, ed., Structural dynamic systems computational techniques and optimization, Gordon and Breach Publishers, 1999.

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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 60 Optimum Design of Arch Dams Including Hydrodynamic Effects for Earthquake Loading Using the Simultaneous Perturbation Stochastic Approximation Method J. Salajegheh, E. Salajegheh, S.M. Seyedpoor and S. Gholizadeh Department of Civil Engineering, University of Kerman, Iran doi:10.4203/ccp.88.60 purchase the full-text of this paper Full Bibliographic Reference for this paper J. Salajegheh, E. Salajegheh, S.M. Seyedpoor, S. Gholizadeh, "Optimum Design of Arch Dams Including Hydrodynamic Effects for Earthquake Loading Using the Simultaneous Perturbation Stochastic Approximation 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 60, 2008. doi:10.4203/ccp.88.60 Keywords: arch dam, earthquake loading, optimal design, hydrodynamic effects, simultaneous perturbation stochastic approximation. Summary An efficient method is presented for shape optimization of arch dams. A finite element model is presented based on linear dynamic behavior of arch dam-water system. Interaction between dam and the foundation rock is not considered and it is assumed to be rigid to avoid the extra complexities that would otherwise arise. Interaction between the fluid and foundation rock is approximately considered thorough a damping boundary condition applied along the bottom and sides of the reservoir. The finite element model involved is compared with exact solutions, reported in literature, and computational performance of the model is verified. The optimization is carried out using simultaneous perturbation stochastic approximation (SPSA) method [1]. This method requires only two measurements of the objective function regardless of dimension of the optimization problem in each cycle of the optimization process. This feature allows for a significant reduction in computational cost, especially for problems with a large number of variables. The load cases included here are gravity load, hydrostatic and hydrodynamic pressure and seismic loading. The seismic load for earthquake records is applied in the upstream-downstream direction of the dam. Time history analysis is also performed using full transient dynamic analysis based on Newmark's method. The design variables are the shape parameters of arch dam and the concrete volume of dam body is considered as an objective function. Design constraints are divided into some groups including the behavior, geometric and stability constraints. The behavior constraints are defined to prevent the failure of each element of the arch dam with a specified safety factor for the earthquake duration. A simple method is also employed to treat time history constraints [2]. In order to ensure the sliding stability of the arch dam, the central angles of the dam is restricted to its critical values. The most important geometric constrains are those that prevent intersection of upstream and downstream faces. In order to assess the effectiveness of proposed method and examine the water effects on the arch dam design optimization, a large arch dam example is investigated. It is observed that fluid-structure interaction has an important role in the design of arch dams and neglecting the water effects on arch dam design will lead to an impractical design. It is also found that the optimization process can efficiently reduce the concrete volume. References 1 J.C. Spall, "Introduction to Stochastic Search and Optimization: Estimation, Simulation and Control", John Wiley and Sons, Inc., 2003. doi:10.1002/0471722138 2 J.C. Arora, "Optimization of structures subjected to dynamic loads", In: C.T. Leondes, ed., Structural dynamic systems computational techniques and optimization, Gordon and Breach Publishers, 1999. 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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