NUMERICAL STUDY OF FLUID-STRUCTURE

INTERACTION IN CONCRETE GRAVITY DAMS

Lamb&, B.M.; Pereira&, P.H.Z.; Azevedo@, R.L.

& Undergraduate student, Western Paraná State University

@ Professor, Dr., Western Paraná State University

ricardo.l.azevedo@gmail.com (Corresponding author)

PRESENTATION TOPICS

• Company Overview (2-3 minutes);

• Problem Description;

• Methodology;

• Objectives;

• Conclusion and future steps.

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).

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.

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, 1994.

• 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: http://www.unioeste.br/reitoria/

PROBLEM DESCRIPTION

• In this work some preliminary results of a 2D FE analysis of a

reservoir- gravity dam system by using Ansys Release 12.0.1

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.

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.

A TYPICAL RESERVOIR-DAM SYSTEM AND

ITS LOADING

GROUND MOVEMENT

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.

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.

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.

NUMERICAL EXAMPLE SELECTED

• Koyna dam subjected to NS component of El Centro

earthquake (1940) (pseudo-dynamic analysis).

NUMERICAL SIMULATION: EXTERNAL

EXCITATION

NS COMPONENT - EL CENTRO EARTHQUAKE (1940)

NUMERICAL SIMULATION

FINITE ELEMENT MESH (COARSE)

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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.

NEXT FE MODEL TO BE ANALYZED (MORE REFINED)

ACKNOWLEDGEMENTS

The authors are thankful to the financial and technical support

provided by CEASB/Itaipu during the execution of this work.

Thank you for your attention !