Zero-force members prevent a truss from becoming a mechanism -- Why?

In summary, the purpose of a zero-force member in a truss is to increase stability during construction, provide added support for changing loads, and prevent the structure from becoming a mechanism. This term refers to a structure that is not able to maintain its shape and stability, which is undesirable. A zero-force member helps prevent this by evenly distributing forces and maintaining the structural integrity of the truss.
  • #1
JakeMEng
1
0
My professor explained to us that the purpose of a zero-force member in a truss is to increase the stability of the truss during construction, to provide added support if the loading is changed and to prevent the structure from becoming a mechanism.

It is this latter point that I do not understand the meaning of. What does it mean for a structure to become a mechanism? Why is this unwanted? Why does a zero-force member prevent this?

Thank you
 
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  • #2
You should get all your answers from the definition of "mechanism".
 
  • #3
Is it like racking?
 
  • #4
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1. What is a zero-force member in a truss?

A zero-force member in a truss is a structural element that experiences no external forces or stresses. This means that the member does not contribute to the overall strength or stability of the truss.

2. Why are zero-force members important in a truss?

Zero-force members are important in a truss because they prevent the truss from becoming a mechanism. A mechanism is a structure that can move or rotate under the influence of external forces, which can compromise the stability and strength of the truss. By including zero-force members, the truss remains rigid and stable.

3. How do zero-force members prevent a truss from becoming a mechanism?

Zero-force members act as redundant elements in a truss. They provide additional support and stiffness, which helps to distribute the forces evenly throughout the truss. This prevents any one member from becoming overloaded and causing the truss to become a mechanism.

4. Can a truss still be stable without zero-force members?

Yes, a truss can still be stable without zero-force members, but it may not be as strong or efficient. The presence of zero-force members helps to evenly distribute the forces throughout the truss, which can improve its overall stability and strength.

5. Are there any disadvantages to adding zero-force members to a truss?

One disadvantage of adding zero-force members to a truss is that it can increase the weight and cost of the structure. In some cases, the extra support provided by zero-force members may not be necessary and can be considered overdesign. Additionally, the placement and design of zero-force members must be carefully considered to ensure they do not interfere with other structural elements or create unwanted stress concentrations.

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