Which of the rules for zero-force members specifies that a colinear load defines the status of non-collinear members?

In the context of statics and the analysis of trusses, the second rule for zero-force members states that if two non-collinear members meet at a joint that has no external load or support reaction, then both of those members are zero-force members. This rule helps in simplifying the analysis of trusses by allowing engineers to identify and eliminate certain members from consideration, as they do not carry any load under the given conditions.

When a collinear load is applied to a joint, it impacts the status of the non-collinear members connected to that joint. Specifically, the application of a force along the line of action of one member means that any member connected at that joint but not aligned with that force can be classified as a zero-force member, provided there are not other load conditions present. This enables engineers to streamline calculations and analyses by focusing only on those members that are actively carrying loads.

Understanding this rule is essential in structural engineering as it lays the foundation for effective and efficient analysis of truss systems, allowing for clearer insights into load distribution and member importance.