Structural Upgrading of Arch Dam under Earthquake Using Tuned Liquid Column Gas Damper (TLCGD)

Upgrading structural damping in civil engineering systems with Tuned Liquid Column Dampers (TLCD) have been extensively investigated during last decades and control vibrations of some buildings and bridges with the dampers have been studied under wind or earthquake loadings. In this paper, the idea is proposed for structural upgrading of arch dam under earthquake with adding a passive Tuned Liquid Column Gas Damper (TLCGD). Adding gas spring effect in TLCD extends the range of its frequency up to 5 Hz. TLCGD increases effectively the damping during the steady-state vibrations of lightly damped structures, within the frequency range of application that limits the maximum fluid speed by about 10 m/s. The response of a real arch dam with a TLCGD is studied here under harmonic motion and earthquake excitation. TLCGD is installed in the level of the uplift. The dynamic analysis of the coupled system is implemented by mode super position synthesis. Empty reservoir is considered to omit the hydrostatic pressure and the hydrodynamic effects and in the meanwhile to omit the radiation damping into the water. So it should be the more sensitive case because of the lowest structural damping, also higher natural frequencies are observed compared to the full or the partially filled reservoir. The equation of motion of an incompressible liquid in the rigid and sealed piping system in normal direction to the mid-plane of the dam body, moving with the dam is described regarding to the piston theory of relative flow and of gas compression by a generalized (non-stationary) Bernoulli equation. Conservation of momentum of the fluid mass yields the control forces o The results show some decrease in displacements under the mentioned loadings and the TLCGD has robustness influences in control vibration of the dam

Keywords:

TLCGD , Seismically Activated Dams , Passive Control