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Static and Dynamic Analysis of Two Dimensions of moshampa dam with Considering Nonlinear Behavior of Concrete Materials
Abstract
Moshampa dam with 108 m height and 416 crest length is located in Zanjan province, Iran. In this study, using finite element method stability of RCC model of this dam, considering the cracking potential of concrete has been analyzed. The behavior of concrete after the failure has been defined using stress-strain function and cracking and hydrodynamic effects of dam reservoir have been considered in interaction form. Since the problem is nonlinear Newton-Raphson method has been used in the analyses. After applying a seismic load in the bottom of the foundation, cracking in dam heel and displacements more than allowable limit occur; this issue causes reforms in primary design of the dam
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In this paper, time-domain transient analysis of elastic dam–reservoir interaction including the reservoir bottom effects is presented by coupling the finite element method in the infinite fluid domain and in the solid domain. An efficient coupling procedure is formulated by a substructuring method. Sommerfeld's boundary condition for the far end of the infinite domain is implemented. To verify the proposed scheme, numerical examples are given to compare with available exact solutions for rigid and elastic dam cases. Finally, a numerical example is studied to evaluate the effects of the reservoir bottom.
Placing portland cement concrete pavement with an asphalt paver is only one of the unique features of roller-compacted concrete pavement (RCCP). It is catching on quickly at military bases throughout the U. S. This paving technology is being developed by engineers at the Waterways Experiment Station (WES) in Vicksburg, Mississippi, as an economical alternative to conventional concrete pavement. It is estimated that this technique could save one-third or more of the cost of conventional concrete pavement construction. This article discusses material characteristics, application considerations, and WES studies.
In this study, the two-dimensional earthquake analysis of a gravity dam-reservoir system using both the Eulerian and Lagrangian approaches is performed. To this aim, the effects of the variation of fluid compressibility on the modal behavior were first investigated. Then, the earthquake response of a dam-reservoir system is investigated using the Lagrangian approach. Parametric studies are conducted on increasing the value of fluid bulk modulus. The results obtained for different values of the bulk modulus are also compared with the Eulerian solutions based on incompressible fluid assumption.
Simplified procedures are presented for the analysis of the fundamental vibration mode response of concrete gravity dam systems for two special cases: (a) Dams with reservoirs of impounded water supported on rigid foundation rock; and (b) dams with empty reservoirs supported on flexible foundation rock. In the first case, the effects of dam-water interaction and reservoir bottom absorption on dam response are included, whereas the effects of dam-foundation rock interaction are included in the second case. In each case, the response of the fundamental vibration mode of a dam monolith is modeled by an equivalent single degree-of-freedom system with frequency-independent properties chosen to represent the effects of complicated, frequency-dependent hydrodynamic terms or foundation-rock flexibility terms, as appropriate. The maximum earthquake-induced deformations and equivalent lateral forces can be computed using the response spectrum for a specified ground motion. The procedures and results presented in this paper are extended in a companion paper to develop a simplified analytical procedure for concrete gravity dams that includes the simultaneous effects of dam-water interaction, reservoir bot- • torn absorption, and dam-foundation rock interaction.
A procedure is developed to analyze, under the assumption of linear behavior, the earthquake response of arch dams including hydrodynamic effects. The dam and fluid domain are treated as substructures and modeled with 6nite elements. The only geometric restriction is that an infinite fluid domain must maintain a constant cross section beyond some point in the upstream direction. For such an infinite, uniform region, a finite element discretization over the cross section is combined with a continuum representation in the upstream direction. The fluid domain model approximately accounts for the effects of foundation flexibility on hydrodynamic pressures. Computed responses of an arch dam to harmonic ground motion are presented.
Based on the scaled boundary finite-element method, the governing equations for the analysis of dam-reservoir interaction
including the reservoir boundary absorption are developed. Coupling with the equation of dam-unbounded foundation interaction,
it can effectively carry out the earthquake response analysis of dam-reservoir-foundation system. The proposed approach has
the advantages that the effect of compressibility of reservoir water as well as the energy absorption of reservoir boundary
on the earthquake response of arch dams and gravity dams can be efficiently evaluated and higher accuracy can be achieved.
In comparison with the methods available in the literature, the computational cost can be reduced to a great extent. It facilitates
the application of earthquake response analysis of dam-reservoir-foundation system including reservoir boundary absorption
to the engineering practice.
This paper presents the application of the finite element method for analysing the two-dimensional response of reservoir-dam systems subjected to horizontal ground motion. The interaction between the dam and the reservoir as well as the compressibility of water has been taken into account. The complete system has been considered to be composed of two substructures, namely the reservoir and the dam. To take into account the large extent of the reservoir, it has been idealized using specially developed infinite elements coupled with standard finite elements while the dam is represented using finite elements alone. Structural damping of the dam and radiation damping in the fluid phase have been accounted for in the analysis. It is concluded that the effect of radiation damping is considerable at high frequencies of excitation. The coupled response of the system is significantly large at and near the fundamental natural frequency of the system in comparison to the uncoupled responses. The method is computationally quite economical, capable of taking into account the arbitrary geometry of the system and is recommended for practical application. Further applications and extensions of the approach to three dimensional analyses are possible.
A general procedure for analysis of the response of gravity dams, including hydrodynamic interaction and compressibility of water, to the transverse horizontal and vertical components of earthquake ground motion is presented. The problem is reduced to one in two dimensions considering the transverse vibration of a monolith of a dam, and the material behaviour is assumed to be linearly elastic
The complete system is considered as composed of two substructures—the dam, represented as a finite element system, and the reservoir, as a continuum of infinite length in the upstream direction governed by the wave equation. The structural displacements of the dam (including effects of water) are expressed as a linear combination of the modes of vibration of the dam with the reservoir empty. The effectiveness of this analytical formulation lies in its being able to produce excellent results by considering only the first few modes. The complex frequency response for the modal displacements are obtained first. The responses to arbitrary ground motion are subsequently obtained with the aid of the Fast Fourier Transform algorithm
An example analysis is presented to illustrate results obtained from this method. It is concluded that the method is very effective and efficient and is capable of producing results to any desired degree of accuracy by including the necessary number of modes of vibration of the dam.
Non-linear responses of dam–reservoir systems are not well understood, because of the lack of an exact time-domain solution for the far field (extending to infinity) of the fluid. This paper presents a procedure for efficient time-domain analyses. It is based on a semi-analytical solution and is suitable for the determination of the interactive behaviour of dam–reservoir systems.
In this formulation, the fluid domain is divided into a near (to the dam) field, which is finite, and a far field extending to infinity. Arbitrary shapes of the upstream face of the dam, and of the bottom of the reservoir floor in the near field, are presumed. Furthermore, the far field is assumed to have a constant depth. The irregular near field is modelled by using the finite element method. A time-domain semi-analytical solution is obtained for the far field. For a vertical dam subjected to earthquake and ramp loadings, numerical solutions obtained compared well with the piecewise exact form of the analytical solution.