Evaluation of TLD Performance in Reducing the Seismic Response of Structures

Tuned Liquid Dampers (TLD) are among passive control devices that have been used to suppress the vibration of structures in recent years. These structures must be adequately presentable as an equivalent single degree of freedom system with long fundamental period. The TLD, located at the top floors of the structure, can dissipate the external input energy into the system through the sloshing effect of the liquid inside the partially filled small containers. The proportions of the TLD are determined such that the liquid’s sloshing frequency is tuned to the vibration frequency of the structure. That will result in optimal performance of the TLD. The interaction between the TLD and the structure takes place through a shear force produced by the difference in hydrodynamic pressure acted upon the TLD walls. In this paper, the application of the TLD in reducing the seismic-induced vibration of the shear buildings will be considered. In this regard, first the governing differential equations of the sloshing liquid are adapted using the nonlinear shallow water wave theory (two-dimensional Navier Stokes equations) for the rectangular tanks subjected to ground acceleration. Using some coefficients obtained for the case of harmonic base excitation, these equations are generalized to consider the different liquid dampings and the wave breaking issue. Then, the equations of the motion of a MDOF shear building is derived taking into account the interaction of the TLD. Numerical simulations were performed to investigate the performance of the TLD for the harmonic base excitations with and without wave breaking and for the earthquake input. Finally, to extend the application of the TLD for the short or intermediate building structures with short period of vibration, a combination of TLD and base isolation system (LRB) is proposed. The performance of the TLD for the base isolated structures under full-scale earthquake loading is studied.