AN ACTIVE PROTECTION SYSTEM FOR WIND INDUCED VIBRATIONS OF PIPE-LINE SUSPENSION BRIDGES

In recent years some large pipe-line suspension bridges, managed by an Italian chemical manufacturer, presented excessive oscillation amplitudes due to wind. Although some passive type measures are available which have proved to be fairly efficient, the problem of protection of the serviceability limit state of these structures (or, in the worst cases, of the ultimate one) is still open to further research and alternative proposals. The particular working conditions of active control immediately dictate the following main characteristics of preliminary design: i) the relative structural simplicity of the feedback scheme and its components, ii) robustness of control, adoption of project and management strategies which permit efficient intervention even given unfavourable initial conditions and with relatively low costs, iii) possibility of an autonomous energy source.