NEHRP Clearinghouse

Title
Dynamic Response of Simple Arch Dams Including Hydrodynamic Interaction.
File
PB81124000.pdf
Author(s)
Porter, C. S.; Chopra, A. K.
Source
National Science Foundation, Washington, DC., July 1980, 287 p.
Identifying Number(s)
UCB/EERC-80/17
Abstract
The substructure method is adapted and generalized for response analysis of arch dams subjected to upstream-downstream, cross-stream and vertical components of ground motion. The arch dam is assumed to be a segment of a circular cylinder, bounded by vertical, radial banks of the river valley enclosing a central angle of 90 degrees. The arch dam and impounded water are treated as two substructures of the total system and displacements of the dam are representeed as a linear combination of the first few natural modes of vibration of the dam alone. For this simple geometry of the arch dam and fluid domain, mathematical solutions of the wave equation are presented to determine the hydrodynamic terms in the finite element equations for the dam. Responses to arbitrary ground motion can be obtained by Fourier synthesis procedures applied to the complex frequency response functions determined by the analysis procedures developed in this report. Numerical results are presented for the complex frequency response functions for hydrodynamic pressures on rigid dams due to each of the three ground motion components. The variation of these pressures with excitation frequency, depth below the free surface of water and circumferential location on the upstream face of the dam is studied, and compared with the hydrodynamic pressures on straight gravity dams. The responses of three arch dams, with different radius to height ratios, are analyzed for three conditions: the dam alone without water, and the dam with full reservoir, considering water to be compressible in one case and neglecting water compressibility in the other case. The complex frequency response functions for accelerations at the dam crest due to the three components of ground motion -- upstream-downstream component, cross-stream component and vertical component -- are presented. These response results are discussed in detail.
Keywords
Earth movements; Arch dams; Finite element analysis; Ground motion; Earthquake engineering; Frequency response; Dynamic response; Hydrodynamics; Earthquakes