cablestayed

A cablestayed bridge, commonly written as cable-stayed or cablestayed, is a bridge in which the deck is directly supported by cables that run from the deck up to towers. These cables are anchored at regular intervals along the deck and connected to the tops of towers, forming patterns such as fan, harp, or semi-fan. The towers primarily bear compressive loads, while the cables carry tensile forces, allowing the deck to be supported without the need for large main cables draped between towers as in suspension bridges.

Construction methods for cablestayed bridges often use cantilever techniques. Towers are erected first, and the deck is built outward from the towers in sections while cables are attached progressively to provide stability. Balanced cantilever construction and incremental launching are common approaches, enabling work to proceed with limited temporary supports and often enabling earlier opening to traffic.

Span and performance characteristics vary, but cablestayed bridges are well suited to medium- to long-span applications. Main spans between towers can range into several hundred meters, with many modern examples exceeding 1,000 meters in longer multi-span configurations. The geometry of the stays—fan, harp, or semi-fan—affects aesthetics, deck stiffness, and construction sequence. Weather and wind response are important design considerations, as with all long-span bridges.

Advantages of cablestayed designs include relatively economical construction for mid- to long spans, shorter approach lengths, and good torsional stiffness. Limitations include the need for tall towers and complex cable arrangements, which can increase maintenance requirements and demand careful wind and fatigue analysis.

Notable examples include the Millau Viaduct in France, with a longest span of 342 meters, and the Sutong Bridge in China, whose main span reaches about 1,088 meters. The modern cable-stayed approach emerged in the 20th century and has since become a standard solution for long-span bridge design.