FLUTTER OPTIMIZATION OF A DOUBLE-DECK TRUSS-STIFFENED GIRDER THREE-TOWER SUSPENSION BRIDGE BY WIND TUNNEL TESTS

Aerodynamic characteristics of double-deck truss-stiffened girders are complex, while existing research is relatively scarce. Taking a double-deck truss-stiffened girder three-tower suspension bridge as the research object, influences of aerodynamic measurements, including the ventilation rate, height of the balustrades, central slotting of upper and lower decks and central stabilizer, on the flutter critical wind speed were studied by section model wind tunnel tests. The results show that flutter critical wind speeds of original cross-section are less than the corresponding flutter checking wind speed at wind attack angles of -3°, 0° and +3°, leading to the possibilities of flutter. The height of the central stabilizer has prominent effects on the flutter critical speed, and the upper central stabilizer on the upper deck can increase the flutter critical wind speeds. The flutter critical wind speed can be increased greatly at the wind attack angle of 0° when centers of upper and lower decks are slotted, while the speed may decrease at a positive wind attack angle. The combined aerodynamic measurements of central slotting of upper and lower decks, reasonably setting the stabilizer and changing the ventilation rate of balustrades can make the flutter critical wind speeds of the bridge meet the requirements at each wind attack angle.