vortex-induced vibrations affect the stability

Question

How do vortex-induced vibrations affect the stability of long bridges?

Answer 1

When wind flows near a bridge, it slows down when comes in contact with its surface and forms boundary layer. At some places, this boundary layer gets separated from the bridge body owing to excessive curvature. And then it leads to the formation of vortex which revises the pressure distribution over the bridge surface. The vortex made may not be symmetric around the bridge body and different lifting forces are formed around the body. And the effect is the bridge body’s motion subject to these vortexes shall be transverse when compared with the incoming wind flow. So as the frequency of vortex shedding reaches near the natural frequencies of the bridges, resonant vibrations begins, the amplitude of vibrations depend on the damping in the system and the motion of the wind relative to the bridges. Such oscillations may “lock-on” to the system and lead to hazardous amplification and fatigue failure.