Concept
Zero force member — where it appears
A member the analysis says carries nothing under this load, which is either a reserve path for another one or material nobody needs.
Named by 2 essays across one field — each of them below, with the objects they name alongside it.
The triangle that cannot fold, and everything built out of it
A square of pinned bars is a mechanism. A triangle is not, and that single fact is the reason trusses exist and the reason they look the way they do.
The structure that survives losing a member
Every check in this collection asks what a structure carries. None of them asks what is left when part of it is gone — and two frames with the same members, the same weight and the same factor of safety can answer that question completely differently.
Named alongside it
The objects these essays reach for when they reach for this one.
Alternative load pathDeterminacyDuctilityMechanismMethod of jointsPanel pointProgressive collapseRedundancyRobustnessTension and compressionTriangulation