SAP2000 does not have a designated truss element, but truss elements can be modeled using frame elements with end releases as described in the following sections.

Approach 1

The frame element becomes a truss if there are moment releases at both ends and a torsion release at one end, and there are no end offsets or joint offsets. This approach works well for isolated truss members. When multiple such members are connected together, the end releases must be coordinated to prevent numerical instabilities or the approach described in the next section should be used.

Approach 2

If your structure is a true truss (i.e. all member are truss members that carry only axial forces), it may be convenient to use the following modeling approach:

• Use only a single member between connected joints.
• Specify M2 and M3 releases at both ends of all members and torsional release at one end.
• Make only translational DOFs available for the analysis by specifying the Space Truss option on the Analysis Options form available via Analyze > Set Analysis Options > Set Solver options.

This approach will eliminate the need to specify different end releases separately for each member. Also please note that even members with end releases still resist their own self-weight by a flexural resistance.

See Also

• Frame FAQ, section "Is there a truss element available in the SAP2000 program?"
• Available DOFs