The dampers are placed where they are the most effective, at the position of largest dis- placement for the principal modes both for the free dampers, and for the anchored damp- ers. The design chose from the outset a slen- der light structure susceptible to perceptible vibrations, but controlled by dampers for each of the significant modes. Very extensive stud- ies, using modal, and step by step methods, were used in the design phase, to predict the acceleration from wind turbulnece and pedes- train steps. However the real structure and the model are inevitably different, with local fric- tion and secondary continuity. After construc- tion the vibrations of the structure were mea- sured and compared with the predictions. This confirmation of the frequencies of the modes permitted in turm the confirmation of the masses in the damping devices. D
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