In order to develop a new type of wind power generation using feedback amplification of the wind-induced vibration caused between tandemly-arranged rectangular and circular cylinders, wind tunnel experiments were conducted. In the feedback control, the rotational excitation of the windward rectangular cylinder controls the vibration of the leeward circular cylinder. When the windward rectangular cylinder is excited with the time lag less than half a period of the leeward circular cylinder vibration, the leeward circular cylinder vibration is amplified efficiently. On the contrary, the feedback excitation with the time lag greater than half a period of the leeward cylinder vibration suppresses the cylinder vibration sufficiently. Although the leeward cylinder vibration is amplified more efficiently as the control gain is stronger, the amplification effect diminishes beyond a critical gain.
Damping measurements on a 200m-high steel office building show an increase and then decrease of damping with amplitude. But current damping predictors for such a building does not account for the decreasing part. There is thus a big discrepancy between the predictor model and actual conditions that implicate unreliability in wind-resistant design. Meanwhile, damping is said to be based on stick-slip phenomenon. This study shows results of theoretical derivations and nonlinear time-history analysis of a one-degree-of-freedom system model with varying stick-slip components. Comparisons of damping estimates are then made between current damping predictor models and the stick-slip damping model.