Experimental identification and verification of a moveable facade element for energy harvesting and vibration control

Abstract

The distributed-Multiple Tuned Facade Damping (d-MTFD) system was proposed to effectively reduce wind-induced vibrations of high-rise buildings by using the parallel moveable outer skin of the Double-Skin Facade (DSF) as damping mass. A full-scale prototype with a 2.8m×2.6m moveable (kinetic) DSF element has been built for first experimental tests using Hardware-in-the-Loop (HiL) simulations. The parallel moveability of the DSF’s outer skin is achieved by mounting it on a smooth-running guide rail system. A stepper motor is applied as an adjustable electrical damper and simultaneously serves as an energy harvester. By using grey-box system identification, all the parameters of the prototype can be accurately estimated. For example, a low equivalent friction ratio of 0.0022 was estimated. The identified model achieved high fitness values (80% to 91%) compared to the measured data, providing the basis for the reliability of the experimental tests using HiL. The prototype is the hardware part of the HiL simulations, which is connected to the simulation part, namely, a 76-story, 306 m high benchmark building assumed to be installed with the d-MTFD system. The feasibility of using a stepper motor as an adjustable electrical damper for semi-active control has been successfully validated based on the HiL simulations. By using semi-active control, the relative displacement of the DSF’s outer skin can be significantly reduced by about 35% compared with using passive control. Energy harvesting performance has also been investigated. The average energy harvesting efficiency of the power electronics was experimentally determined as approximately 75%. With consideration of all the parasitic damping in the connection, the average energy harvesting efficiency was about 50%. For tests under across-wind excitation with a return period of 10 years, the self-sufficient operation of the semi-active d-MTFD system was proven to be achievable based on the prototype results. The average harvested power of the whole benchmark building (with 1000 moveable facade elements) can be predicted as 1.3 kW.