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How do I model tension only members?

In many cases, tension only members such as cables, or compression only members can be adequately modelled with a single bar element and using the Tension / Compression Only piecewise linear bar material.  

Attributes > Material > Tension / Compression Only (Bar)

Please see the help for more information:

Help > Help Topics > Contents > Modeller Reference Manual > Chapter 5 - Model Attributes > Material Properties > Specialised > Piecewise Linear Bar Material Model (inc Tension / Compression Only)

Where elements other than bars are to be used tension or compression only behaviour can be modelled using joint elements at a connection (Eg. cables modelled with multiple beam elements to allow cable sag and the associated geometrically nonlinear behaviour to also be taken into account). See the following help topic for more information regarding the modelling of cables:

Help > Help Topics > Index > (click) "How to ..." > (click) "How to model cables"

Key considerations when using joint elements for this purpose include the geometry of the model, selection of appropriate mesh and material attributes, and calculation of appropriate joint stiffnesses.

Joints defined for this purpose will have different properties according to loading conditions; this requires repeated updating of the stiffness matrix and a nonlinear solution is therefore required. 

Superposition of load is not applicable in nonlinear analyses. It is therefore important to ascertain if the use of tension-only members is appropriate. Does the total loading on the structure lead to compression in members which cannot support such a load? Certain individual loadcases may appear to cause compression, but when combined with dead loading and other permanent or coexistent loads, compression may not be possible.  If it is necessary to adopt a nonlinear tension-only approach, a full nonlinear loading procedure will need to be adopted since superposition of loads is not valid. 

Use the links below to obtain advice on generating tension-only members:

Tension only between point features Tension only between edges of surface features Tension only between faces of surface features

Joints: Mesh | Geometric attributes | Material attributes | Spring stiffnesses | Supports | Loadcase properties

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