Instability issues in extremely long-span steel cable-stayed bridges

Static and dynamic problems associated with extremely long- span self-anchored steel cable-stayed bridges are discussed, and structural countermeasures to overcome the span limitation are given. Since the load carrying-capacity of the girders is the most important concern in self-anchored cable-stayed bridges, the method of examining it is briefly explained, then the statically stable cross-sectional dimensions of girders with a span of more than 1000 meters are presented. Since wind-induced vibration is also an important issue to ensure the safety of cable-stayed bridges, dynamic problems of the girder, tower(s) and cables are explained and the aerodynamic and mechanical means to mitigate hazardous vibrations are presented.