SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/eng-truss-members-axial

In an ideal pin-jointed truss, what kind of force does each member carry?

Only axial tension or compression, along the member's length.

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  1. Only axial tension or compression ✔
  2. Mostly bending
  3. Mostly twisting

Why: Each member is a two-force member: loads only at its two pinned ends. For it to balance, those forces must line up along the member, so it is simply pulled or pushed.

Huh, didn't know that: Real trusses are welded or bolted, but the pin model works well because members are long and slender.

The dad joke
Truss members are simple folks. They're either tense or compressed, never bent out of shape.
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References

Answer: Only axial tension or compression. Each member is a two-force member: loads only at its two pinned ends. For it to balance, those forces must line up along the member, so it is simply pulled or pushed.

  1. Engineering Statics (Baker and Haynes): 6.3 Trusses engineeringstatics.org/Chapter_06-trusses.html
    Because trusses contain only two-force members, these internal forces are all purely axial.
    Checked 2026-10-10.
  2. Engineering Statics (Baker and Haynes): 6.4 Method of Joints engineeringstatics.org/method-of-joints.html
    A common practice is to assume that all unknown forces are in tension
    Checked 2026-10-10.

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