Shear stress resisted by a bolt

[fonseh]

Homework Statement

In this problem , why the author use (30x10^3) /s = VQ / I only ? Shouldnt it be 4(30x10^3) /s = VQ / I

Homework Equations

The Attempt at a Solution

I said so , because the board at the centered is connected by 4 bolts , 2 on the left and 2 on the right . The faces on the right also resisted by the same arrangement of nails , right ?

 

[PhanthomJay]

Homework Statement

In this problem , why the author use (30x10^3) /s = VQ / I only ? Shouldnt it be 4(30x10^3) /s = VQ / I

Homework Equations

The Attempt at a Solution

I said so , because the board at the centered is connected by 4 bolts , 2 on the left and 2 on the right . The faces on the right also resisted by the same arrangement of nails , right ?

Where did the 30x10^3 come from? Regardless, your method is wrong. In determining Q for bolt shear, either you use the top right board full area, or the top left board full area, or the middle and 2 bottom areas divided by 2 ( this last method not recommended, but may help conceptually with your understanding).