From the abstract:
It is ... demonstrated that the ultimate failure of the bridge was in fact related to an aerodynamically induced condition of self-excitation or ``negative damping'' in a torsional degree of freedom. The aeroelastic phenomenon involved was an interactive one in which developed wind forces were strongly linked to structural motion. This paper emphasizes the fact that, physically as well as mathematically, forced resonance and self-excitation are fundamentally different phenomena.
