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Can someone please explain why the support at C does not have a vertical reaction force while the support at E has? Doesn't the support at C have the same kind of pin connection as the support at E?


The rod BC is a two force member. Therefore, the forces on either end must be along the axis of the member. i.e. since the rod is horizontal, the forces on either end can only be horizontal.

The beam AGDE is not a two force member. Therefore, it can have forces on the ends in both directions.

In other words, the reason that the reactions are different does not have to do with the pinned boundary, but one of the members being two force and the other not.

If this doesn't make sense, I would suggest you look up "two force member" in your textbook.

  • $\begingroup$ I fully grasped it. Thanks for the explanation. $\endgroup$ Sep 24 '17 at 13:30

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