Cables, Cable meshes

The entire bridge construction illustrated is hung on the two braced pylons. The span of the roadway between the foreshore bridges is 250 m.
The entire bridge construction illustrated is hung on the two braced pylons. The span of the roadway between the foreshore bridges is 250 m.

The cable elements allow the calculation of any cable structure following the theory of large deformations.

They can be combined with beam, area and solid elements and can be calculated in the state 'slack' or prestressed.

A special feature of cable structures is that the final system geometry results from the balance between the cable forces and the outer loads.

Together with the additional module 'FEM Dynamics' challenging problems of nonlinear cable dynamics can be solved.

Cable meshes

This example illustrates the problems of shape determination, calculation and dynamic analysis of cables.

First of all, the flat cable grid is 'pulled' into the desired geometry by specifying deformations.

For instance, one could raise the four central nodes:

Mesh geometry after raising the central nodes
Mesh geometry after raising the central nodes

Alternatively, the three edge nodes could be raised

Mesh geometry after raising the edge nodes
Mesh geometry after raising the edge nodes

Dynamic analysis requires the existing cable forces to be integrated into the system as these have a significant influence on the vibrational behavior of the system.

4th Eigenmode with the cable forces from prestressing and dead load (1.46 Hz)
4th Eigenmode with the cable forces from prestressing and dead load (1.46 Hz)