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Statics Forces Problem (Trusses)

  • #1

Homework Statement



I was doing a problem with my friend (the image that is attached to this) and when looking up a solution online... It said that the forces at reaction supports B and C are 5 kN in the y direction...


Homework Equations





The Attempt at a Solution



We thought that since these members are trusses, all the force from the external loading... is 15 (10 + 5) and that the reaction supports in the y direction at B and C should be 7.5. Where did we go wrong?

Thank you! :)
 

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  • #2
SammyS
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Homework Statement



I was doing a problem with my friend (the image that is attached to this) and when looking up a solution online... It said that the forces at reaction supports B and C are 5 kN in the y direction...

Homework Equations



The Attempt at a Solution



We thought that since these members are trusses, all the force from the external loading... is 15 (10 + 5) and that the reaction supports in the y direction at B and C should be 7.5. Where did we go wrong?

Thank you! :)
What is the reaction force at A ?
 
  • #3
If it is a truss... Do we still account for the reaction force at support A in the y direction?

If this was the case and I took the moment at A I would get :

-1*(10) + -2*(5) + (2-0.707)*By + (2+0.707)Cy = 0
=> 1.293*By + 2.707*Cy = 20

And for the sum in the y direction of the system:

Ay + By + Cy = 15

(Assumption) Since Cy = By:

By = 5
Cy = 5
Ay = 5
... Ok... I just solved it... :P

Thanks Dude. :D
 

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