Abstract: As a countermeasure against storms for long span, particularly super-long span suspension bridges with the center span exceeding 2,000 m, there is provided a super-long span suspension bridge which can be improved of its static and dynamic wind resistance performance by applying a mass to a portion of the girder. In a suspension bridge with the center span exceeding 2,000 m, a mass application member capable of temporarily carrying a predetermined amount of additional load is provided on either side of the stiffening girder for a distance equal to 1/3 at the maximum of the center span so that a mass weighing 30% or less of the weight of the girder is temporarily applied in the mass application member in the girder on the windward side when the bridge is subjected to a storm, and cross stays are provided each at a point inward from either end of the center span section at a distance equal to 1/4 to 1/3 of the center span.

Abstract: The stiffening girder type suspension bridge according to the present invention is designed with a smaller dead load under normal conditions, and applied with a temporary dead load as an additional mass to improve the static characteristics and aerodynamic stability when the bridge is subjected to particularly violent storms that result in significant vibrations and swaying of the bridge. The present invention bridge structure is highly economical. A passage is provided in the stiffening girder at the center of its width along the direction of the bridge axis, so that a temporary dead load as an additional mass can be moved into the passage. Under normal conditions, the passage is kept empty of the load. When an imminent storm is anticipated, a given amount of liquid or solid is transferred into the passage located within the stiffening girder to temporarily apply a given amount of temporary dead load to the stiffening girder during a storm to control vibrations of the bridge caused by the winds.

Abstract: A streamlined box girder type suspension bridge comprises a plurality of towers for supporting the cables, and the center main span and side spans comprising streamlined box girders suspended by a plurality of hangers from the cables. An additional mass of an appropriate weight comprising the material which would not directly contribute to the strength of the box girder is formed as a core at the predetermined portion of the box girder in order to suppress the bending-torsional flutter arising from the streamlined shape of the box girder, and the core extends over the complete span of the bridge symmetrically and with respect to the longitudinal axis thereof.