Zero force member

In the field of engineering mechanics, a zero force member refers to a member in a truss which, given a specific load, is at rest -- neither in tension nor in compression. In a truss a zero force member is often found at pins (connections within the truss) where no external load is applied and three or fewer truss members meet. Recognizing basic zero force members can be accomplished by analyzing the forces acting on an individual pin in a system.

"NOTE: If the pin has an external force or moment applied to it, then all of the members attached to that pin are not zero force members UNLESS the external force acts in a manner that fulfills one of the rules below."

1. If only two members meet in an unloaded joint, both are zero-force members.
2. If three members meet in an unloaded joint of which two are in a direct line with one another, then the third is a zero-force member.
3. If two members meet in an unloaded joint and the line of action of the load coincides with one of the members, the other member is a zero-force member.

External links

* [http://www.vcity.ou.edu/demoModules/analysis/truss/truss.htm Truss Overview]
* [http://em-ntserver.unl.edu/NEGAHBAN/EM223/note12/note12.htm Another Truss Overview]

ource

Engineering Mechanics Volume 1: Equilibrium by: C. Hartsuijker and J.W. Welleman