New Reduced-Mass Controlled TMD for Tall Building Vibration Mitigation

Felix Weber
R&D Engineer

Tall and slender structures are prone to wind-induced vibrations, which may lead to unacceptable peak accelerations, causing discomfort. One way to guarantee the required vibration comfort is to install tuned mass dampers (TMD) in the vicinity of the highest occupied floor. Due to the extremely large modal mass of tall buildings, and because of the narrow-to-broad-band nature of wind excitation, the TMD mass may be up to 2,000 metric tons. The recently developed “smart TMD,” based on real-time controlled oil dampers, ensures the vibration comfort criteria, but with reduced pendulum mass compared to classic TMDs. The control force is generated by the hydraulic dampers that are necessary for TMDs in any case, but here, the hydraulic dampers are equipped with real-time control valves to manage their actual force. The control algorithm is programmed to achieve the required vibration comfort, using less TMD mass than would be the case with passive TMDs. Depending on the project specifications, the mass reduction can be up to 20%. To avoid impact of the pendulum mass on the primary structure during earthquake excitation, the control is enriched by an adaptive pendulum motion-control algorithm.

This presentation describes the whole framework of a “smart TMD,” consisting of: computational fluid dynamics (CFD) analysis of the wind-induced building vibrations, calibrated by wind tunnel tests; model-based optimum design of the new semi-active TMD; prototype tests of the semi-active hydraulic dampers; and the structural vibrations expected from the new semi-active TMD for wind excitations.

Accompanying PowerPoint Presentation