Abstract
Coupled flutter oscillation of a very long span suspension bridge is numerically investigated by complex eigenvalue analysis of 3D frame model under various wind load conditions. Conclusions are as follows:
1) Complex eigenvalue analysis for flutter problem may solve uncertainties of ordinary methods.
2) Usually selected bending and torsional modes do not always develop into the critical flutter mode.
3) Selberg's estimation always gives the lowest critical wind speed of coupled flutter, although there is difference in the appeared flutter normal mode. Therefore it can work as a conservative index of coupled flutter in the wind resistance design procedure.