Question on a certain calculation

[jenofstructures]

I have a question on a certain calculation in the
Design of Anchor Reinforcement in Concrete Pedestals by Widianto, Patel and Owen.... I found it in google and I also uploaded this on the link below,

my question is that on page 14 of the article, there's a formula involving the bearing area:

Abrg = 0.866*2^2-5/4 * 1.25^2

i know that "2" came from the anchor head, and "1.25" is the diameter of anchor, but where did they get the "0.866" and "5/4" respectively?

thank you in advance!


Poems are made by fools like me, but only God can make a tree. engineers creates wonderful buildings, but only God can creates wonderful minds

 

[JedClampett]

There's a typo in the formula and it affects the answer. It should be pi/4, not 5/4. The bearing area of a 1.25 diameter bolt with a heavy hex head is 2.237 in^2.
As far as the .866, I don't have the formula in front of me, but that must be the factor to calculate the area of a hexagon.

 

[chichuck]

I can confirm JedClampett's statement:

for a Hexagon, A = 0.866*d^2

d = distance across the flats.


chichuck

 

[jenofstructures]

thank you very much

Poems are made by fools like me, but only God can make a tree. engineers creates wonderful buildings, but only God can creates wonderful minds