Abstract: Steel truss girders are a common structure type for long-span suspension bridges.The flutter stability of this structure type is poor.Therefore,aerodynamic optimization measures are usually adopted to increase the criti- cal wind speed of the flutter.In this investigation,based on a long-span steel truss girder bridge located at a mountain area,the wind tunnel tests of the section model were conducted to detect the critical wind speed of the flutter,and the influences of the general aerodynamic measures including the central stabilizer,the horizontal sta- bilizer and the stabilizer under the top lateral bracing on the critical wind speed of the flutter were discussed.It is found that the general aerodynamic measures have attack angle effects on the critical wind speed of the flutter.Therefore,isolated aerodynamic measures are proposed,which include the isolated horizontal stabilizer,the grat- ing horizontal stabilizer and the isolated stabilizer under the top lateral bracing.The results show that these isolated aerodynamic measures can improve the attack angle effects to a certain degree,thus increasing the critical wind speed of the flutter.

Key words: steel truss girder, flutter, optimization measure, attack angle effect, isolated improvement