Identification of Flutter Derivatives By Forced Oscillation Method

• Main Authors: Shi-Wei Jian, 簡仕為
• Other Authors: Jong-Cheng Wu
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/38179597727920887955

碩士 === 淡江大學 === 土木工程學系 === 92 === In wind engineering application, the technique developed for the conventional free oscillation method to obtain flutter derivatives of bridge deck sections has become more mature. This method is easy to use and results are mostly satisfactory in the application. However, based on our past experimental experience, the test results from this method are sometimes unreliable under the circumstances when the influence of vortex shedding is significant or the operations during tests are not cautious. Unlike the conventional method, in this thesis, the author proposes a new approach for determining the flutter derivatives by using forced oscillation technique. In the forced oscillation tests, a bridge deck section is connected to a two-axis shaking table driven by two servo-motors, which produces forced vibration actions in two degree of freedom to the deck. By measuring the response of bridge deck under wind load, the transfer function of the response in the presence of the interaction between the wind load and the bridge deck can be computed by using the Fourier analysis. From the comparisons with the theoretical analysis, the flutter derivatives can be derived. The experimental results show that the flutter derivatives obtained from the forced oscillation method are not consistent with the wind speed varied. Further investigations will be conducted for the explanation of such a phenomenon.