Abstract
Structural characteristics of the Old Tacoma Narrows Bridge which was collapsed in 1940 by wind was exactly investigated for both the eigenvalue calculation and the flutter analysis to grasp natural frequencies and the torsional flutter response characteristics of the Bridge. It was found from these numerical simulation analyses that 1st symmetric torsional flutter might have been presented if a pair of center stays was not broken, although 1st asymmetric flutter was excited in the Bridge. It was also found that 1st asymmetric torsional flutter, which was the same flutter mode in the destroyed Bridge, seemed to be induced in case that a pair of center stays was broken and that lower wind velocity less than 19m/s acted on half length of either side span.
