Study on Identification of Parameters for Cable-Stayed Bridge Deck Buffeting Response Analyses and on Related Numerical Simulations

• Main Authors: Chun-Hsu Chang, 張君旭
• Other Authors: Rwey-Hua Cherng
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/00616831865851633967

博士 === 國立臺灣科技大學 === 營建工程系 === 96 === As the main spans of bridges become longer, engineers have to assess the wind induced vibration of bridge decks for safety and serviceability. Generally, either the full bridge model wind tunnel test or section model wind tunnel test with analytical procedure is used to evaluate buffeting responses of bridges. Modal parameters, including modal frequencies and damping ratios, are usually obtained by finite element models; aerodynamic parameters, including aerodynamic coefficients and flutter derivatives, are obtained by section model wind tunnel test. In this research, modal and aerodynamic parameters are obtained by identifying filed measurement results and numerical simulations respectively. This study proposes a method, combing empirical modal decomposition, random decrement technique with Hilbert transform, for identification of modal parameters in time domain from modally coupled response time histories. Aerodynamic and aeroelastic phenomena of blunt sections are simulated by numerical simulations; the associated aerodynamic coefficients are evaluated; flutter derivatives are identified by stochastic subspace identification method. Vortex shedding and reattachment phenomena are observed in the simulated results. The obtained aerodynamic parameters are compared with those of the wind tunnel test in the literature, and indicated that aerodynamic coefficients approach to the average of wind tunnel test results, flutter derivatives are higher estimated slightly. Finally, numerical simulations are conducted for a bridge section; the interaction effect of fluid-bridge section is accounted by an arbitrary Lagrangian-Eulerian strategy. Finally, the root mean square values of bridge buffeting responses are evaluated by an approximate analytic formula using the obtained parameters. These results can be used to assess safety and serviceability of the bridge. The effects of modal parameters, aerodynamic coefficient and flutter derivatives on buffeting responses are also investigated.