Dynamic Soil Structure Interaction Study

The effect of the surrounding soil, as depicted by the soil-structure interaction effect, on the dynamic behavior of Brezina concrete gravity arch dam, located in El-Beyadh at the west of Algeria, is investigated in the present study. Both modal and transient analyses are performed for the dam, presented and discussed as a case study for this work. A three-dimensional finite element model (SOLID185) using ANSYS software is created to model the dam body and the adjacent soil. Three different seismic records having identical peak ground acceleration of 0.2g, assuming three different viscous damping ratios: 2%, 5% and 10%, are used in the analysis. The results of this analysis constitute a data base for a parametric study investigating the soil-structure interaction effect, that of the mass of soil foundation and that of the damping ratio on the dynamic behavior of Brezina concrete arch dam. Dynamic analyses for Brezina concrete arch dam for the three studied cases: dam without soil, dam with mass soil foundation and dam with massless soil foundation show that the presence of the soil in the model develops more stresses in the dam body, especially when the soil mass is considered in the model

Deterministic seismic damage analysis for concrete gravity dams: a case study of oued fodda dam

One of the major dangers for seismic damage of concrete dams is the propagation of cracks in dam concrete. The present study undertakes a numerical investigation of the seismic damage for Oued Fodda concrete gravity dam, located in the northwest of Algeria, considering the impacts of properties of joints along the dam-foundation rock interface and cross-stream earthquake excitation. Three-dimensional transient analyses for coupled dam-foundation rock system are carried out using Ansys software. The hydrodynamic effect of reservoir fluid is modelled using the added mass approach. The smeared crack approach is utilised to present the seismic damage of dam concrete using the Willam and Warnke failure criterion. The dam-foundation rock interface joints are presented with two ways, adhesive joints and frictional joints. The Drucker–Prager model is considered for dam concrete in nonlinear analyses. Consideration of the study results indicates that the frictional joints model can reduce the seismic response and damage hazard of the dam body to a better extent compared with the adhesive joints model. Furthermore, the application of cross-stream earthquake excitation reveals the significant effect on cracking response of the dam in the two models of joints

Effect of dam–rock foundation interaction modeling on the modal ratio-related quantity of Beni Behdel and `El Mefrouch multi-arch dams

Using the Beni Behdel dam and the El Mefrouch dam as example studies, this paper intends to clearly demonstrate how modeling of the interactions between rock foundations and dams impacts the modal behavior of these two multi-arch dams. The uniqueness of this study is that the modal behavior of each dam is represented in terms of related parameters (period, participation factor, ratio, and effective mass), and more precisely in terms of ratio (defined as the ratio between the participation factor of the mode i and the maximum participation factor), as opposed to other works that have expressed this behavior in terms of frequency. In this article, stiff rock foundation, massless rock foundation, and massed rock foundation are the three methods used to simulate dynamic interactions. The investigated dams are three-dimensionally simulated using the ANSYS finite elements code. The modeling of the rock foundation–dam interaction has an effect on the fundamental mode value, its location, and the related parameters, according to the results. Furthermore, it is found that the upstream–downstream direction is not always the most important direction for dams and that interaction modeling influences the resonance bandwidth, which affects the forecast of the resonance phenomenon

Impact of material nonlinearity of dam-foundation rock system on seismic performance of concrete gravity dams

This paper shows the impact of material nonlinearity of a dam-foundation rock system on seismic performance of Oued Fodda concrete gravity dam, located at northwestern side of Algeria. For the purpose, a three-dimensional dam-foundation rock system finite element model is employed in analyses. The hydrodynamic interaction between reservoir water and dam-foundation system is implicitly taken into consideration by the Westergaard approach using surface finite elements added to dam-fluid and foundation-fluid interfaces. The concrete material model is used to present the cracking of dam concrete under a seismic load the using smeared crack approach based on the Willam and Warnke failure criterion. The materially nonlinear analysis for both dam concrete and foundation rock is performed using Drucker- -Prager model. According to numerical results, tensile stresses and maximum strains reduce significantly in the materially nonlinear model. In addition, the cracking areas in the dam decrease also when material nonlinearity characteristics of the dam-foundation rock system is considered in analyses