Nonlinear Dynamic Analysis of Concrete Arch Dam Considering Large Displacements

Abstract eng:
In this research, geometrically nonlinear dynamic analysis of arch concrete dam is attempted. At first, suitable models for large deformation analysis of massive plain concrete structures are investigated and by considering arch dam special features and properties, proper model for large displacement analysis is developed. A nonlinear analysis of the Morrow point arch dam using the Saint Venant–Kirchhoff model for large displacements is carried out under an intensive ground motion of order of 1.0g for the peak ground acceleration. Fluid-Structure interaction is modeled including water compressibility and reservoir bottom absorption although the foundation is considered as rigid. It was indicated that considering large deformation effects could reduces the displacement response of dam. This reduction of the peak response observed in this analysis was about 6 % in respect to that of the linear dynamic. On the other hand, large deformation effects reduce compressive stresses and increases tensile ones. Values of these changes are about 9 % for maximum compressive and 6% for maximum tensile stresses for the same ground motion level. Although it could be understood that the structural behavior of an arch dam does not allow large strains in a general manner, but one could not rule out the appearance of large displacements, specially under joint-opening. Thus it is suggested that for large seismic loads a consistent inclusion of this type of nonlinearity is necessary in order to grasp a proper image of concrete arch dam dynamic behavior.

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