Stability check

Simple rules that keep a truss stable, and how Truzme tells you when one can move.

Last updated 2026-09-24

Keep it stable

Three rules, and a structure built with them will almost always solve without trouble:

• Triangulate. Every panel a triangle.
• Hold every node in both directions. At least two members or supports at every node, not in a straight line.
• Use one pinned support and one roller. And don't point the roller straight at the pin.

Why these work, and every way a truss can still move, is explained with pictures in Truss stability.

Every structure in that file breaks one of these rules on purpose — a good way to see each failure on its own, and fix it.

When something's still wrong

Truzme checks all of this on every edit, with no button to press. The moment a structure fails, the toolbar's stability icon flags it.

Some failures are harder to spot: the supports look right, and the structure still isn't stable. Open this one and click the stability icon to open the Stability panel — it shows exactly why:

Equilibrium

Action + Reaction = 0

Underneath all the specific checks, there's one real test: add up every external force on the structure — every load and every support reaction — and the total has to be exactly zero, in both the horizontal and the vertical direction. That's equilibrium: whatever pushes has to be pushed back exactly as hard.

Hover a load or a reaction to highlight it on its own, so the sum can be checked one force at a time instead of all at once.