Lesson 1, Topic 1
In Progress

Structural Form #2 – Cables

Abdulaziz July 21, 2020

Cable structure, Form of long-span structure that is subject to tension and uses suspension cables for support. Highly efficient, cable structures include the suspension bridge, the cable-stayed roof, and the bicycle-wheel roof. The graceful curve of the huge main cables of a suspension bridge is almost a catenary, the shape assumed by any string or cable suspended freely between two points. The cable-stayed roof is supported from above by steel cables radiating downward from masts that rise above roof level. The bicycle-wheel roof involves two layers of tension cables radiating from an inner tension ring and an outer compression ring, which in turn is supported by columns.


Cables are far more efficient than beams – the same amount of material will carry a much greater load. The problem, however, is that a cable only works in tension, and so the load must be in line with the cable. Thus cables are not as useful, and hence not as popular, as beams. The most famous examples of cable structures are suspension bridges, where the main cable supports many hanger cables,

Golden Gate View At Dusk
Golden Gate View At Dusk

Another form is the cable stayed bridge where the cables connect directly to the deck.

Design revealed for world’s longest and tallest cable-stayed bridge *

The triple-towered, double-decker crossing will feature the longest continuous cable-stayed deck in the world at 3.2km, surpassing both the Millau Viaduct and China’s Jiaxing-Shaoxing Sea Bridge. 

Bridge (https://www.bridgeweb.com/)

Cables have the unique property that the shape of the cable changes as the load changes, so that the cable always carries tension only.

Because cables change shape to suit the load (always carrying the load by tension and never by bending moment, shear or torque), we give cables a special name – funicular structures. We will use the concept of funicular structures later in this course.

Aerial top view of cable-stayed Suspension bridge and Highway road with green forests in Finland.
Aerial top view of cable-stayed Suspension bridge and Highway road with green forests in Finland.