Preliminary design of very long-span suspension bridges

The feasibility of very long-span suspension bridges is analysed. The relation between the geometrical parameters, the load and the material characteristics is first discussed in order to find out the limit value of the span length. An iteration procedure is then proposed to study the main aspects of the structural behaviour in the deflection theory. The results of a numerical investigation allow to state that the behaviour of a very long-span suspension bridge, both in terms of stresses and deflection, is similar to the behaviour of an unstiffened cable, the contribution of the girder being negligible.