Which members in the truss are zero force?

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Discussion Overview

The discussion revolves around identifying zero-force members in a truss structure, specifically focusing on the conditions at Joint C, which has four members connected. Participants are exploring the rules and reasoning behind determining zero-force members in truss analysis, particularly in the context of an upcoming exam.

Discussion Character

  • Homework-related, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions the identification of zero-force members at Joint C, noting that it is unloaded and has two non-collinear members connected, yet neither is identified as a zero-force member.
  • Another participant asserts that having four members at a joint means a zero-force member cannot be identified based on the standard rules.
  • There is agreement that Joints E and K are loaded due to reaction forces.
  • A later reply suggests that equilibrium calculations would still leave four members and a force at Joint C, implying uncertainty about the effectiveness of such calculations in identifying zero-force members.

Areas of Agreement / Disagreement

Participants generally agree that no zero-force members can be identified at Joint C due to the presence of four members, but there is uncertainty about the implications of this and the effectiveness of equilibrium calculations in this context.

Contextual Notes

The discussion highlights limitations in the rules for identifying zero-force members, particularly in cases with four members at a joint, and the dependence on specific conditions that may not be fully addressed in the participants' contributions.

DiamondV
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Homework Statement


Okay, I need help quick, exam in few hours, I won't be able to reply to this later.

http://puu.sh/lQeXl/42907b0a12.jpg

In my lectures notes this is given. In the example shown with it, the one on the right in particular. Look at Joint C, it is unloaded, it also has to members connected to CG and CH both of which are non-collinear, but neither is zero force? I know technically there are 4 members connected to Joint C but I have no rule for 4 members so I just thought maybe we just ignore the other two(sounds weird) No other info about zero force members was given.

Also one more thing, Joints E and K, they are loaded due to the reaction forces correct?

Homework Equations


N/A

The Attempt at a Solution


N/A[/B]
 
Last edited by a moderator:
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DiamondV said:
no rule for 4 members
That simply means you can not identify a zero-force member there.
DiamondV said:
Joints E and K, they are loaded due to the reaction forces correct?
Correct

Good luck with your test ! :smile:

--
 
BvU said:
That simply means you can not identify a zero-force member there.
Correct

Good luck with your test ! :smile:

--
So I would have to do out the equilibrium calculations to find if there are any zero force members connected to a joint with 4 members.
 
Don't think that will help: then you still have 4 members (and a force). But I'm not an expert, so not sure.
 

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