LARGE SCALE CONSTRUCTIONS: LONG SPAN CABLE SUPPORTED BRIDGES

Aim of the paper is to give simple qualitative evaluations of the feasibility of ex-treme span cable supported bridges. The fan-shaped cable-stayed bridge scheme and the suspension one are examined. An analysis of the statical and dynamical behaviour of these schemes is developed by using both a continuous model and a discrete one of the bridge. The structural model of the bridge is defined according to a diffused arrangement of stays and of hangers along the girder. Agreeing analytical and numerical results which are able to capture the essential features of the statical and aerodynamic behaviour of the bridge are given. It is shown that more than the statical deformability, the aerodynamic instability is the relevant technical limit to the increasing of the span length.