engleski

Influence of vehicles on bridge aeroelastic stability

The long span suspension and cable-stayed bridges are particularly sensitive to wind effects due to low natural frequency and mechanical damping, which makes studies on bridge aeroelastic behavior particularly important when designing those engineering superstructures. The focus of this work is on traffic-induced bridge-deck vibrations due to interaction of airflows, vibrating bridge-deck section and vehicles for the Kao Pin Hsi Bridge in Taiwan. The aeroelastic phenomena studied in this work are flutter and galloping. The aerodynamic flutter is analyzed based on dynamic tests in a form of nondimensional flutter derivatives, while the galloping is studied through the quasisteady approach by applying the Glauert-Den Hartog criterion. The experiments were carried out in the Climatic Wind Tunnel of the Centre of Excellence Telč, Czech Republic. The effects of dynamic stiffness of the system on flutter derivatives were studied as well. The bridge-deck section is used together with a multipurpose experimental setup originally developed in the Centre of Excellence Telč. Flutter derivatives were obtained by the means of the free- vibration technique for the single and double degrees of freedom of the system. For the single-degree-of-freedom system the direct flutter derivatives with respect to the pitch motion indicate that the bridge deck without vehicles is the most sensitive to flutter, while all tested configurations prove to be dynamically stable with respect to the heave motion. The same trends are observed when analyzing the bridge-deck section as a double- degree-of-freedom system. Dynamic stiffness of the bridge-deck section proves not to influence the flutter derivatives. The results obtained from the lift and drag coefficients as function of the attack angle indicated that the analyzed bridge was not prone to galloping type of self- excited vibration.

Wind ; vehicles ; bridge ; aeroelastic stability

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