Hexagonal Geodesic Domes - Bridges


Most of the material about bridges that used to be on this site has now moved - to: http://suspensiondomes.com/.

This page indexes the few resources that still remain here.

Tensile bridges are the largest clear span structures in the world.

In the following diagrams, only the white struts are intended to be capable of sustaining compressive loads - all other elements are tensile.

Hyperboloid bridges

Hyperboloid bridge

The hyperboloid is a simple tensile structure, which I believe has - or should have - substantial significance for bridge builders.

The hyperboloid is one of the two "doubly ruled" structures. Its surface consits entirely of straight lines, the roles of which can be conveniently played by cables. The degree of central constriction can be varied - by placing cables at different angles.

Practical constructions often consist of two sets of cables - one twisting to the left, the other twisting to the right.

The cables can be woven togther, using rectangular or triaxial weaving patterns.

Also, the two sets of cables can sometimes be placed at slightly different angles to the main axis of the bridge - so that neither set of cables is quite straight. This causes the two concentric sets of cables to press into each other dynamically.

As far as I know only one hyperboloid bridge has been constructed:



Hyperboloid towers - on the other hand - are more common.

Segmented hyperboloid bridge

This consists of a series of hyperboloid strutctures chained together.

It represensts the principle of distributing the compression elements along the length of the bridge - rather than concentrating them at each end as is done in a suspension bridge.

There are pros- and cons to doing this.

As far as I know the best-known segmented hyperboloid structure is a tower in Russia: the [Shukhov tower].

Aspension bridges

Another approach to constructing large-span tensile structures exists. This has its roots in "Aspension" structures - an idea which originated with Buckminster Fuller.

Just as dome designers appear to have neglected "suspension" principles, so bridge designers appear to have neglected aspension designs.

Simple segmented bridge

This is one of the simplest segmented bridges I can think of.

Face-bonded octahedral bridge

Here's a design based on the idea of face-bonding octohedra.

Twisting hexagonal bridge

This bridge has a more complex design. It offers a significant unobscured central aperture.

Twisting hexagonal bridge

This bridge has a more complex design. It offers a significant unobscured central aperture.


Tensegrity tube bridge

Tim Tyler | Contact | http://hexdome.com/