Semiactive Tuned Liquid Column Dampers: Experimental Study

A tuned liquid column damper (TLCD) is a special type of auxiliary damping device which relies on the inertia of a liquid column in a U-tube to counteract the forces acting on the structure. Damping in the TLCD is introduced as a result of headloss experienced by the liquid column moving through an orifice. The primary objective of this paper was to examine the performance of a prototype semiactive TLCD. Experiments were conducted to determine the dynamic characteristics of a coupled structure-TLCD system. The experimental setup included a prototype TLCD attached to a model of a single-degree-of-freedom structure which was mounted on a shaking table. The prototype TLCD was equipped with an electropneumatic valve to provide optimal damping at a wide range of structural motion amplitudes. The optimum absorber parameters, i.e., the optimal tuning ratio and damping ratio, were determined experimentally and compared to the analytical results obtained previously reported by the writers. A control strategy based on gain scheduling was utilized, which was designed to maintain the optimal damping based on a prescribed look-up table. This scheme was experimentally validated. It was noted that the semiactive system provided an additional 15–25% reduction in response over a passive system. Finally, a design example was presented to demonstrate the application of semiactive TLCDs to tall buildings under wind loads. The response of uncontrolled structure, braced structure, and structure with a passive damper, and semiactive damping system using numerical simulations were compared. The semiactive TLCD reduced the RMS acceleration at the building top by 45% at all wind speeds.