Modeling Cables in RISA-3D

One of the support questions we get most often is, “How can I model a cable element in RISA-3D?”

Cables that are straight and experience only axial loading can be easily modeled. When modeling structures with cables (such as guyed structures) the cables can be modeled as tension only and doing so will ensure that the member will not take any compression.

Click the link below to our RISA-3D Help File. Search 'Tension/Compression-Only Members'. 

In addition to setting the member as tension only, it is necessary to utilize a weightless material so that the transverse cable member deflections are not reported. To do this, you can create a new material and set the density to zero.

Note: If the cable weight is removed, it should still be applied elsewhere on the structure as a point load. If you do not do this then the cable deflections (other than the axial deflection) will be reported as very large since it is the cable action that keeps a guyed cable straight.

Lastly, if the design requires a cable prestress, thermal loads can be used to create the pre-tension of the cable. See Prestressing with Thermal Loads to learn how to do this.