I was looking through AISC Design Examples Version 14.0 page IIA-104 and I am stumped on where the 4.5 and 1.5 values are coming from in their calculation for Znet at the top of the page. Can someone help me out on this one?
moment arm from the bolts to the center line of the angle. 4.5 in to the outer bolt set and 1.5 in to the inner bolt set. Subtracting out the bolt hole area from the plate area for the net Z.