LOWER PROFILE: Anti-bounce dampers added to London's controversial Millennium Bridge last year as part of a £5M retrofit designed to stop lateral sway have changed the crossing's elegant profile, structural engineer Arup confirmed this week.
Arup associate Roger Ridsdill Smith said the extra weight of the dampers had caused a 'realignment of the cable profiles' which was predicted by the redesign work.
As a result, the centre span is around 400mm lower at its mid- point, with smaller deflections in the side spans. This in turn means that the structure changes direction more suddenly at the piers.
A total of 29 pairs of tuned mass dampers weighing up to 2.5t each were fitted under the bridge deck across the three spans to prevent any possibility of the lightweight structure bouncing vertically in phase with pedestrian footfalls.
INFOPLUS www. nceplus.co.uk/magazine/millenium