Hello, All these timber sizing questions..... I know this is a lot but for you all who are adept at this help would be greatly appreciated.
I am having a little trouble with how to proceed on this formula to find allowable bending force.
S=M/F
I have not derived S but know its formula to be bd^2/6. A transverse section such as (8")(12")^2/6= 192in^3.
An example: (Longleaf Pine) I want to size a simply supported beam. The tributary area is 220 ft^2 (10'X 22').
DL= 174 lb/linear foot
LL= 1000 lb/linear foot
TL= 1174 lb/linear foot
W= 22' x 1174= 25828 lbs
V (Shear)= W/2= 12914
M (Internal Moment) = WL^2/8
= (1174 lb/ft)(22')^2/8
= 71027 lb/ft
I think I now have M and S, so I can calculate F
f =actual bending stress
S=M/F
f=M/S
f= 71072lb/ft / 192in^3
f= 370lb/ft/in3
Now, first of all how many errors are in this? Is there a table to cross reference f with? And lastly is it best to solve for f this way or use a table (if there is one) to find S?
