Find reactions at supports and bending/shear/axial diagrams

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SUMMARY

The discussion focuses on calculating reactions and forces in a frame subjected to uniform loading, specifically a total force of 100 kN. The vertical and horizontal components of the loading are determined to be 60 kN and 80 kN, respectively. The vertical reactions at the roller and pin supports are calculated as Vr = 160/3 kN and Vp = 170/3 kN, respectively. The conversation emphasizes the importance of resolving forces into components to analyze shear and axial forces effectively within the structure.

PREREQUISITES
  • Understanding of static equilibrium equations (Fx=0, Fy=0, M=0)
  • Knowledge of reaction forces in structural analysis
  • Familiarity with free body diagrams and their application
  • Ability to resolve forces into components (axial and shear forces)
NEXT STEPS
  • Study the method of sections in structural analysis
  • Learn about shear and moment diagrams for beams
  • Explore the principles of static equilibrium in frames
  • Investigate the effects of point loads on structural members
USEFUL FOR

Structural engineers, civil engineering students, and anyone involved in analyzing forces in frames and beams will benefit from this discussion.

gacb17424
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Homework Statement


0aac393504.png

Force by uniform loading = 20(5) = 100kN
Vertical component of the uniform loading = 20(5)(3/5) = 60kN
Horizontal component of the loading = 20(5)(4/5) = 80kN
vertical reaction at roller support = Vr
vertical reaction at pin support = Vp

Homework Equations


Fx=0, Fy=0, M=0

The Attempt at a Solution



Finding reactions[/B]
Horizontal reaction is only at pin support. Let it be Hp. As Fx=0
Hp=80-40=40kN (to the left)
So I take moment at pin support first so as to find out Vr
Vr=[40(1)+50(3)+60(7.5)-80(2)] / 9 = 160/3 kN (upwards)
take moment at roller support to find Vp
Vp=[100(2.5)+50(6)-40(1)] / 9 = 170/3 kN (upwards)

Attempt to find out the equations for diagrams
for the left part of the frame (free body)
9f4498861d.jpg

Resolving Vr into two component
let the one perpendicular to frame be Rp, Rp = 32 kN
the other one along the frame be Ra, Ra = 128/3 kN
distance from roller be x
Axial force = Ra = 128/3 kN
Shear force = 32-20x,
M=32x-10x2

But for the middle part and right part of the frame, how do I consider the free body? and the segments divided by the point loading?
I tried thinking to cut at the top-right corner to consider the right part of the frame as a free body but then what should I do for the segment between the P2 loading and the corner?
The middle part is even more messy to me.
Thanks!
 
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The idea behind the free body is that you can separate a particular member from the rest of the structure as long as you include the loads at the ends as well as any loads applied directly to that member.

You've started your calculation of the reaction forces and moments with the sloped member on the left of the frame. Figure out which loads from the sloped member are transmitted into the top member, thence to the vertical member on the RHS of the frame.

Remember, the frame as a whole remains static, so the individual members must be static as well.
 
SteamKing said:
The idea behind the free body is that you can separate a particular member from the rest of the structure as long as you include the loads at the ends as well as any loads applied directly to that member.

You've started your calculation of the reaction forces and moments with the sloped member on the left of the frame. Figure out which loads from the sloped member are transmitted into the top member, thence to the vertical member on the RHS of the frame.

Remember, the frame as a whole remains static, so the individual members must be static as well.
Thanks for your reply! Before I proceed, I want to make sure something.
In my calculation for the left body, I resolve vertical reaction into two components. One is used to find out the shear force and one is the axial force along the beam.
Is my concept here correct? If this is the case, how do I balance Rh here?
a6bd24c976.jpg
 
gacb17424 said:
Thanks for your reply! Before I proceed, I want to make sure something.
In my calculation for the left body, I resolve vertical reaction into two components. One is used to find out the shear force and one is the axial force along the beam.
Is my concept here correct? If this is the case, how do I balance Rh here?
a6bd24c976.jpg

You've calculated the reactions on the sloped member in a coordinate system which is aligned with that member. What you need to find is how these forces are transmitted into the other member(s)of this frame. IOW, you need to find the components of the forces which are aligned with the other member attached to the sloped member.
 

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