I have a structure colored in blue which we are looking directly downwards on (birdsview). Its high up in the air, and the only thing keeping it from falling down is the friction surface (red) between structure (blue) and the steel plate (black line). The reason there is enough friction to keep the entire thing together is due to bolts (grey lines) pulling the whole thing together with a strong force, which creates friction.
What I am wondering is which of these two cases, given that the force pulling them together is equal, would see the highest friction force. Case 1 only has 2 friction surfaces, but the surfaces are larger. Case 2 has 4 friction surfaces, but the surfaces are much smaller. Since friction is F= N*μ the friction surfaces might not even matter and it only depends on the force pulling it all together?