NUMERICAL STUDY OF FLUID-STRUCTURE INTERACTION IN CONCRETE GRAVITY DAMS

Transcription

1 NUMERICAL STUDY OF FLUID-STRUCTURE INTERACTION IN CONCRETE GRAVITY DAMS Lamb &, B.M.; Pereira &, P.H.Z.; R.L. & Undergraduate student, Western Paraná State Professor, Dr., Western Paraná State University ricardo.l.azevedo@gmail.com (Corresponding author)

2 PRESENTATION TOPICS Company Overview (2-3 minutes); Problem Description; Methodology; Objectives; Conclusion and future steps.

3 Center for Advanced Studies on Safety of Dams (CEASB ) Leveraging the expertise of Itaipu - the world's largest hydroelectric power generation - and the technological environment and innovative Itaipu Technology Park (PTI), was established 2008, the Center for Advanced Studies on Safety of Dams (CEASB), a partnership between the Itaipu Dam, through the Corporate University Itaipu (UCI), the Foundation Technology Park Itaipu - Brazil (FPTI-BR) and Western Paraná State University at Foz do Iguaçu (Unioeste).

4 Center for Advanced Studies on Safety of Dams (CEASB ) The CEASB has a technology platform with potential for development of the strategic solutions in dam safety. The applied research projects are consistent with the process of upgrading the plant and the program of R & D of Itaipu, in addition to contributing to the mission of PTI promote the development of relevant scientific-technical Trinational Region.

5 WESTERN PARANÁ STATE UNIVERSITY UNIOESTE AT CASCAVEL/PR The Western Paraná State University - UNIOESTE originated by the integration of four municipal colleges, being recognized in December 23, UNIOESTE has currently about 10,000 students (in 34 undergraduate/32 graduate programs). In the latest assessment of MEC/INEP, it figures as the 13th best university in Brazil. source:

6 PROBLEM DESCRIPTION In this work some preliminary results of a 2D FE analysis of a reservoir- gravity dam system by using Ansys Release are presented; The structure (gravity dam) is assumed to be elastic and analyzed by plane strain formulation; The water contained in the reservoir is considered a weakly compressible, inviscid fluid. So far, reservoir bottom absorption effects are neglected.

7 PROBLEM DESCRIPTION (cont.) An implicit time-domain analysis is performed. External excitation: ground acceleration due to El Centro earthquake (1940); Infinite fluid-domain is modelled into a finite one using a truncation boundary condition.

8 A TYPICAL RESERVOIR-DAM SYSTEM AND ITS LOADING GROUND MOVEMENT

9 ANALYSIS OF COUPLED DAM-RESERVOIR SYSTEM Westergaard (1933) => 'classical', added-mass approach: incompressibility of water / rigidity of structure. Simplified approaches: first assume the dam to be rigid: the resulting pressure field is imposed on the dam to obtain the structural response; Coupled field aproaches: solution of the coupled system is done by solving the two systems separately with the interaction effects enforced in a iterative fashion.

10 METHODOLOGY The solid dam is discretized by using finite elements (PLANE42); Loadings considered: hidrostatic pressure + hidrodynamic pressure given by Westergaard formulation; Proportional (Rayleigh) damping is adopted; Implicit time marching scheme, unconditionally stable.

11 OBJECTIVES To simulate numerically the effect of the ground movement on a concrete gravity dam through a simplified treatment of the dynamic coupled system dam-reservoir.

12 NUMERICAL EXAMPLE SELECTED Koyna dam subjected to NS component of El Centro earthquake (1940) (pseudo-dynamic analysis).

13 NUMERICAL SIMULATION: EXTERNAL EXCITATION NS COMPONENT - EL CENTRO EARTHQUAKE (1940)

14 NUMERICAL SIMULATION FINITE ELEMENT MESH (COARSE)

15 DEFORMED CONFIGURATION, DISPLACEMENTS AND EQUIVALENT STRESS AND STRAIN

16 CONCLUSION AND FUTURE STEPS Preliminary results obtained so far seems to be adequated, at least from a qualitative point of view; Some mesh convergence studies are needed to allow a better comparison with reference results, published in the literature. These studies are in progress nowadays.

17 NEXT FE MODEL TO BE ANALYZED (MORE REFINED)

18 ACKNOWLEDGEMENTS The authors are thankful to the financial and technical support provided by CEASB/Itaipu during the execution of this work.

19 Thank you for your attention!