engleski

Flutter and galloping of bridge decks with roadway wind barriers

Wind tunnel-experiments are carried out to analyze the effects of wind barriers on flutter and galloping of bridge decks. The focus is on aerodynamic shape of bridge decks, as three different bridge-deck sections (streamlined, semi-bluff, and bluff) are studied. The standard 5 m high (in full-scale) wind barrier with 30 % porosity is placed at the windward (leading) edge of bridge decks. The analyzed parameters include aerodynamic force and moment coefficients, the Glauert-Den Hartog criterion for galloping, and flutter derivatives. The experimental results obtained with the wind barrier in place are compared to those acquired at empty bridge decks without the wind barrier. With respect to steady aerodynamic loads, the wind barrier generally increases the drag force coefficient, which is particularly exhibited for the streamlined bridge deck. The lift force coefficient of the bluff bridge deck is influenced the most by the wind barrier. Influence of the wind barrier on the pitch moment is particularly exhibited for positive wind incidence angles. The wind barrier does not influence the galloping sensitivity of the studied bridge decks, as the Glauert-Den Hartog criterion is positive in the entire range of investigated wind incidence angles. It however deteriorates the dynamic stability of all the studied bridge decks with respect to torsional flutter. This observation is particularly exhibited for the streamlined bridge deck. While the empty streamlined bridge deck (without the wind barrier) is dynamically stable with respect to torsional flutter, it is sensitive to torsional flutter with the wind barrier in place. The wind barrier deteriorates the dynamic stability in torsional motion for the semi-bluff and bluff bridge decks as well, but to a lesser extent than it is the case for the streamlined bridge deck.

Bridge decks ; Roadway wind barrier ; Aerodynamic forces and moments ; Galloping ; Flutter ; Wind-tunnel experiments

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