Analysis of Multispan Suspension Bridges

Multispan suspension bridges can be exactly and conveniently analyzed by the writer's method, which was derived by means of finite difference calculus with due consideration to the flexure of towers. The method can be applied to bridges with any number of spans, irrespective of whether the cables rest on movable saddles or are anchored at tower tops. Results are shown of analyses made on a 5,000 m five-span bridge with a 1,500 m center span and on a 3,220 m four-span bridge, both tentatively designed for the crossing of the Inland Sea of Japan. The four-span bridge with a rigid A-frame center tower has considerable stiffness and other merits. Bridges of this type can be of great advantage if used at sites where the construction of a rigid A-frame center tower is feasible.