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When the bridge was tested before its
opening its builders, Arup, discovered that as more people walked on
the bridge it began to wobble from side to side. The "Millenium
Wobble" was cured by fitting dampers to the bridge.
Most of the dampers can only be seen
from underneath. The V shaped struts (known as chevron bracing)
that you can see in this photo are an important part of the
damping. The points of the chevrons meet above the cross-members and
are slightly offset from each other. Joining them is a sort of
shock-absorber called a fluid-viscous damper. There are 37 of
these along the length of the bridge. Each side of these dampers you
can also see heavy weights suspended on large coil springs. These
are called tuned mass dampers and help to stop the deck of
the bridge bouncing up and down. There are 26 pairs of these.
Additional damping was also provided at the southern approach ramp.
You can find out much more detailed
information from
Arup's own website. |
