Transient analysis of concrete gravity dam-reservoir systems by Wavenumber-TD approach: Fid-Bau Portal

Transient analysis of concrete gravity dam-reservoir systems by Wavenumber-TD approach

Lotfi, Vahid / Zenz, Gerald

Abstract The Wavenumber approach was initially introduced as an ideal substitute for the rigorous type of analysis which had been the basis of extensive studies in seismic analysis of concrete gravity dams. The former technique is formulated in the context of pure finite element programming, while the latter relies heavily on a two-dimensional semi-infinite fluid element (i.e., hyper-element). Recently, a variation of Wavenumber method was proposed which was referred to as Wavenumber-TD approach. The approximation to the original technique improves its realm of application and allows it to be carried out in time domain as well as frequency domain. In that study, the formulation was examined for harmonic type of excitation which proved to be promising. Herein, this will be evaluated for its real intended application, which is transient analysis of dam-reservoir systems. For this aim, the prepared special purpose finite element program is modified and the analysis of Pine Flat dam is considered as a typical example. Several models are considered with different values of normalized reservoir length. In each case, the reservoir truncation surface is treated by Wavenumber-TD and the extensively utilized Sommerfeld conditions. The dynamic loading considered is the S69E component of Taft earthquake record. Furthermore, two types of reservoir bottom condition of full reflective as well as absorptive, are adopted. Overall, this will allow for a thorough examination and evaluation of Wavenumber-TD approach in regard to its effectiveness.

Highlights • A novel formulation (i.e., Wavenumber-TD) is proposed for dynamic analysis of concrete gravity dams. • Wavenumber-TD approach is an effective and robust approach which may be utilized in time domain. • The method has produced acceptable results for the case of low reservoir length and full reflective base. • The method can be implemented in the context of Pseudo-Symmetric technique for its time integration. • The method is extremely advantageous since it leads to accurate results even with small reservoir length.