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Shape Optimization of Concrete Arch Dams

Takalloozadeh, Meisam | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 47760 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen
  7. Abstract:
  8. Finding an initial point to start classical optimization methods is privileged to finding an algorithm. It is due to high dependency of final result to selection of initial point, which is independent of type of the algorithm. In engineering optimization where space of problem has several local extremums, this fact has higher effects. In the present study, to overcome this problem in finding optimum shape of concrete arch dams, a two-stage approach is proposed. In the first stage (discrete stage), using the developed stress-constrained topology optimization, an initial optimum shape is obtained. Afterward in the next stage (continuous stage), the optimum shape obtained from previous stage is used as the initial point. For this purpose, the design variables are extracted from the obtained optimum shape. In the first stage, the optimum shape is obtained without any assumption by using the modified “Pareto” method. Topological sensitivity used in Pareto method is developed for materials with Drucker-Prager failure criterion which is modified for structures under body force. The result of the first stage is close to the global optimum shape of the dam and the rate of convergence is at a much faster rate, comparing to intelligent methods which are usually used to find the global optimum. In the second stage, classical optimization methods are used to find the final optimum shape. Moreover, abutment stability which has great effect on the shape of the concrete arch dams, is considered in the second stage. For this purpose, Londe method is used to evaluate the safety factor of wedges against sliding and additional constraint is added to optimization problem. To avoid the effect of unreal stress concentration obtained in linear analysis of concrete arch dams on increasing the dam body’s volume, a non-dimensional design index is introduced. Moreover, by using this index, an approach to find the optimum shape of concrete arch dams under earthquake loading is proposed. The method is based on obtaining several optimum shape on Pareto frontier and selecting the optimum shape among them by their performance criteria under earthquake response
  9. Keywords:
  10. Concrete Arc Dam ; Sensitivity Analysis ; Shape Optimization ; Topology Optimization ; Drucker-Prager Yield Surface ; Pareto Improving ; Design Index ; Abutment Stability

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