# Bending Moments

• Mar 18th 2009, 10:33 AM
88engine
Bending Moments
Hi all
I'm a trainee studying Civil Engineering at College.
I am stuck on a few things and will fail my course by the end of the week if I do not get this done...

I have a problem where I have to draw shear force diagrams and bending moment diagrams. I have done the loading diagram and the shear force diagram but am completely stuck with the bending moment diagram.

The beam is 10m long with a 92.5kN force acting up on the left hand end, there are 2m to the 40kN/m UDL which lasts for 4m, then there is 2m to the next upward force of 77.5kN then a further 2m to the end of the beam which has a 10kN downward force on the end. I have calculated it on each metre, therefore I will end up with 10 points to plot on my bending moment diagram and each metre has been given a letter; A to K.

I hope I have explained this well - if not I could scan a copy in but this may take me a couple of days and I don't really have a couple of days to play with.

I have got my calculations right along the beam to the point where the 77.5kN force comes in (so I have 2 more calcs to complete then I can draw the bending moment diagram. I have no idea what to do with the 10kN force on the end. The following calculations are what I have used:

A = 0
B = 92.5 x 1 = 92.5
C = 92.5 x 2 = 185
D = (92.5 x 3) - (40 x 0.5) = 257.5
E = (92.5 x 4) - (80 x 1) = 290
F = (92.5 x 5) - (120 x 1.5) = 282.5
G = (92.5 x 6) - (160 x 2) = 235
H = (92.5 x 7) - (160 x 3) = 167.5
I = (92.5 x 8) - (160 x 4) = 100
J = (92.5 x 9) - ***STUCK***
K = (92.5 x 10) - ***STUCK***

As you can see I do not know what to do with the last 2 calcs. The last one needs to come out with 0!

ANY help will be taken with so much thanks - as I'm a trainee, if I fail this course I will also be sacked... please help.

Thanks for your time and in advance of any help or guidance.
88engine