It's been a few years since I've done any statics problems...
The following is an example from the book "A timberframer's workshop". In this example, it shows that a snow load is uniformly distributed on the roof at 30 lb/sq. ft. While I understand the mathamatical calculation they used to recude the uniform load to 1800, 3600, and 1800 at points U1, U2, and U3 respectively, what I am not comfortable with is why they distributed the loads like this. When they multiply 6X300 = 1800 = U1, is that 6 feet from the left side, or from the middle? Would there also be load from the show at the far left and right points(L1 and L3). The sum of forces and moment calcs are no problem, but it's just understanding this load distribution that's got me a little confused...

Should be "load from the snow" not show. Too bad the edit fundtion still doesn't work.

Hi Brad,

You are correct to think that in the "equivalent" point load case outlined above that some of the load should be heading directly to the support points thereby reducing overall load applied through the frame, however the "equivalent" point load case presented in the calculation is not the same as the uniform load case and results in quite different bending moments and shear distributions.

For example, bending would be approximately 3 - 4 times higher and shear would be 10 - 20 times higher for the uniform load case, depending on the degree of fixity assumed at each of the joints. Axial loads (tension and compression) are much the same.

Regards

Ken Hume