Trusses

Trusses are support members that are joined together at the ends. The function of a truss is to transmit loads to a support joint. In this section, we will analyze a simplified version of planar trusses called simple trusses, which consist of two-force members connected by frictionless joints/pins.

Truss Assumptions

The main assumptions for trusses and truss structures are:

1. All loading is applied at the joints.
2. The weight of the truss is negligible.

Because of these assumptions, all trusses are two force members, with the forces on the truss acting along the axis of the member.

Two Force Member

A two force member is a rigid body that has two forces (no moments) acting on it in two locations. Assumptions of two force members (for equilibrium to hold):

1. |F_A| = |F_B|
2. F_A
3. F_A

Zero Force Member

Zero force members are members in a truss structure that experience no force. They act as support trusses to add stability, but are not load bearing. There are 2 cases where zero force members occur:

1. Two noncolinear members share a pin with no support or external forces (Zero force member example, left)
2. Two colinear forces with a third noncolinear force on a pin (zero force member example, right)

Insert content here from TAM 212 reference page - Free Body Diagrams - Rigid Bodies - Trusses section. This has a really good analysis of eliminating zero force members to simplify the structure

Truss Analysis: Joints

Truss Analysis: Sections