Experimental investigation of utilizing TLD with baffles in a scaled down 5-story benchmark building

A tuned liquid damper (TLD) is a special type of auxiliary damping device, which relies on the sloshing of a liquid (water) in a container to counteract the forces acting on the structure. Damping in the TLD is introduced as a result of liquid sloshing and wave breaking. A conventional TLD is generally tuned to the main frequency of the building and is less efficient in other frequencies. Because of this limitation, the TLD is usually used to control the structural response of structures, which could be simulated as a SDOF structure, and mostly due to wind forces.In this paper a new kind of tuned liquid damper with some installed rotatable baffles is studied experimentally. The main idea behind installing such baffles is to compensate the effects of probable mistuning of the TLD and also it is an effort toward making the TLD more controllable, i.e. a semi-active damper.Response of a five story benchmark building was utilized to investigate the contributions of these baffles on efficiency of tuned liquid damper under dynamic and earthquake excitations. By observing the performance of TLD with baffles, the study investigates the influence of a number of parameters, include the following: baffles angles, frequency ratio, mass ratio and especially the effects of probable mistuning with changing the depth of water and orientation of baffles. The damping ratios of the building for a range of baffles angles were evaluated using logarithmic decrement technique. The results that are obtained in this paper show that the displacement and acceleration responses of the structure under the free vibration test utilizing the baffles reduced up to 2.5% and 3.9%, respectively, when compared with the case where no baffles are employed. Also the dynamic magnification factor under harmonic excitation reduced up to 2.7% proportional to baffles angles. Damping of the structure equipped with this type of TLD increased in a range of 3.93–6.38% when compared to the case of using no damper. The displacement and acceleration responses of the building under scaled down earthquakes also decreased up to 24.07% and 27.24%, respectively, with some of the best control results occurring before full closure of baffles.

► Effects of rotatable baffles on characteristics of TLD are experimentally studied.
► TLD with baffles was placed on a benchmark building and tested on the shaking table.
► TLD with baffles caused the responses of the building better than no baffles.
► Utilizing baffles inside the TLD makes its characteristics more controllable.
► Baffles can be employed to compensate the effects of mistuning.