# Determining bolt diameter.

## Homework Statement

We were provided with the dimentions and specifications for a highway sign, and given assumptions for weight and wind forces acting on it. Firstly, we had to calculate the reactions at the base. And then draw stress blocks and Mohr's circle for four points on the base of the section.

Now I need to determine a suitable bolt size and orientation for the base plate supporting the sign. I'm a bit unsure of how to do this. I basically just need to make a reasonable assumption (say, four bolts) and test what size diameter bolt I would require in order to be sufficient (using manufacturer specs as a guide to their tensile and shear strength, and a factor of safety of 1.5).

But I'm getting myself a bit muddled. In the normal textbook problems it's simple because the force is provided. But I don't know whether I use the stresses from my stress blocks to determine the force on the bolts? Or just my reactions? We can ignore bending of the base plate, I just need to know where I get my values for my forces from?

tau = V/A
sigma = F/A

See above.