What does it mean to be a zero-force member?

We have some rules to help us find these zero force members. These can be easily found by simple inspection.

All members of a truss have only one axial force. A member whose axial force is zero is called a zero force member.

We use two methods for truss analysis: Method of Joints or Method of Section

What is Zero Force Member for Truss?

Zero-Force members: These structural members support no loading and help to stabilize the truss. Two-Force members: These structural members are not subject to any applied or reaction moments and can only be loaded at two pin joints.

Also Read: Parapet Wall

Method of joints

The summation of vertical and horizontal forces for any truss joint is zero.

This method is not useful if the structure is large and requires member force in any section.

Method of section

It employs all three static equilibrium equations. We should make sure that there are no more than three members or forces unknown.

Also Read: What Is Modulus of Rupture

Solving Trusses

Solving a truss is identifying and determining unknown forces that are carried by members of the truss while supporting an assumed load. These internal forces are purely axial because trusses only contain two-force members. 

The first step in analyzing a truss structure is to determine the internal forces. The next steps include refining the initial analysis, taking into account other load conditions, accounting the weight of members, loosening the requirement that members be connected to frictionless pins and finally determining the stresses within the structural members as well as the dimensions necessary in order prevent failure.

Also Read: Contour Interval