Improvement of aeroelastic instability of shallow π section

From an economical point of view, a two-plate-girder bridge section has been examined as a bridge section for a long span suspension bridge. The two-plate-girder bridge section of H or π section inherently does not have good aerodynamic performances, as shown by the accident of the Tacoma Narrows Bridge with H section-type bridge girder. On the contrary, in the present paper, there has been an attempt to find the possibility of the aerodynamic performance improvement of the two-plate-girder bridge section of the π section by changing the intervals between the two plate girders. With respect to wind tunnel test results, in the vortex-excited vibration in heaving vibration mode, the on-set wind velocity and the vibration amplitude decrease with interval between two plate girders, and the flutter on-set wind velocity increases. These results show the possibility of aerodynamic performance improvement of the two-plate-girder bridge section.