Master Shear Force Diagrams with this Helpful Homework Example

[ryanmcarthy]

Homework Statement

Hi,
I know how to draw simple Shear Force Diagrams, but I am struggling with the example in the below picture, as it has a UDL.

Homework Equations

The Attempt at a Solution

Normally for the solution, I should start the diagram at 26.7, then across and down to 16.7, then across and up to 70, then across and down to 50.

But as it has a UDL I know this changes things! How do I start the diagram, and I will have a go at doing it. Do I start at 26.7, or do I need to do something before this?


Thanks a lot

 

[ryanmcarthy]

I've come up with this, but don't know if I started correctly?

 

[pongo38]

The left half is correct. In the 5m stretch between the 10 kN load and the Reaction R2, what would you expect the change of shear force to be? The figure of -28.7 seems wrong to me. As the final result on the right is not 20 kN, you know you have gone wrong. I recommend you draw this to scale on squared paper. In that case, you should see the gradient of the graph is the same throughout.

 

[ryanmcarthy]

Thanks a lot for the relpy! I can't draw it on square paper, as I am at home and don't have a scanner (only at work).

Is this attempt better? I'm not sure if I need to go down to zero at the end though?

Thanks

 

[L2E]

That is now correct, you can check your answer here,

http://learntoengineer.com/beam?f=2,u1|8,u2|3,-10|10,-20&d=0,10!-5&m=

The SFD does have to go back down to 0 at the end. The shear force and bending moment of any beam is 0 at a free end.

 

[ryanmcarthy]

Hi,

Thanks a lot for the help!