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In this article we present the performance of concrete gravity with absorptive reservoir bottom and soil– structure–fluid interaction. A two-dimensional direct coupling methodology is presented to evaluate the performances of dam–reservoir-foundation coupled system. A reflection coefficient is introduced to simulate the reservoir bottom absorption. The fundamental frequency of reservoir has a decreasing trend with increase of reflection coefficient and the responses of individual sub-systems with different reservoir bottom depend on exciting frequency. However, this effect decreases continuously with fluid–structure and soil– structure–fluid interaction. [ABSTRACT FROM AUTHOR]

The article analyzes fluid-structure systems considering the direct coupled effect of elastic dam and the fluid adjacent to it. The study considers three different modulus of elasticity of dam and compares the tip displacement of dam, maximum hydrodynamic pressure and different principal stresses. It examines the flexibility of dam to alter the behavior of dam-reservoir system, as well as the role of the elastic effect of dam structure on the analysis of fluid structure interaction problem.

The assessment of response of an aged concrete dam is important for the prediction of its behavior during earthquakes, so that remedial measures can be taken at the right time to withstand future earthquakes. The assessment is necessary, since the analyses procedures may become obsolete and the state of the art may change as the time of construction and the structural material may deteriorate due to harsh environmental conditions. At the same time, the sediment will be accumulated at the reservoir bottom on the upstream side of the dam. The process of siltation depends on the reservoir topography and climatic variability, i.e., increased flood frequency and river inflow. The decision of retrofitting or strengthening the aged dam necessitates accurate analysis of the same in the presence of accumulated sediment. In this paper, an approach to include the time-dependent degradation of concrete owing to environmental factors and mechanical loading in terms of isotropic degradation index is presented. The absorption of pressure waves at the bottom of the reservoir due to the presence of sediments has been incorporated in the hydrodynamic pressure equation. The response of an aged concrete dam in the presence of sediment layers under seismic excitation is studied. The outcomes show the efficiency of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Abstract: The design of seismic resistant concrete gravity dam necessitates accurate determination of hydrodynamic pressure developed in the adjacent reservoir. The hydrodynamic pressure developed on structure is dependent on the physical characteristics of the boundaries surrounding the reservoir including reservoir bottom. The sedimentary material in the reservoir bottom absorbs energy at the bottom, which will affect the hydrodynamic pressure at the upstream face of the dam. The fundamental parameter characterizing the effect of absorption of hydrodynamic pressure waves at the reservoir bottom due to sediment is the reflection coefficient. The wave reflection coefficient is determined from parameters based on sediment layer thickness, its material properties and excitation frequencies. An analytical or a closed-form solution cannot account for the arbitrary geometry of the dam or reservoir bed profile. This problem can be efficiently tackled with finite element technique. The need for an accurate truncation boundary is felt to reduce the computational domain of the unbounded reservoir system. An efficient truncation boundary condition (TBC) which accounts for the reservoir bottom effect is proposed for the finite element analysis of infinite reservoir. The results show the efficiency of the proposed truncation boundary condition. [Copyright &y& Elsevier]

It is important to predict the behaviour of an aged concrete gravity dam during an earthquake and to assess its degraded capacity to withstand future earthquakes, so that remedial measures can be taken at the right time. The assessment of operating and ageing dams is more important, since the analyses procedures may become obsolete and state of the art may change since the time of construction. In this paper, an approach to include the time dependent degradation of concrete owing to environmental factors and mechanical loading in terms of isotropic damage index is presented. An effective numerical algorithm for seismic analysis of a concrete dam in the vicinity of an infinite reservoir with the application of damage mechanics considering fluid-structure interaction is presented. The performance of an aged dam with a known percentage of isotropic or orthotropic damage due to seismic excitation is studied. [ABSTRACT FROM AUTHOR]