Homework SourseSelect the lightest rectangular Douglas fir section for the
Select the lightest, rectangular Douglas fir section for the cantilever beam of 8-ft span that will carry a uniform load of 300 lb/ft
Select the lightest, rectangular Douglas fir section for the cantilever beam of 8-ft span that will carry a uniform load of 300 lb/ft
Solution
total length of the beam is 8 feet
total load 300 lb/ft
for 8 feet 8*300= 2400 lbs
convert into N
2400*4.45=10680N
from the standard tables
Area = 10.875in2 = 67.96
I = 47.635 in4
bending stress 900 MPa
to check for shear
f= 1.5V/A
1.5*10680/67.96
235.72 MPa
hence the design is safe for shear loading
