by Archer40 » Thu Mar 29, 2018 1:06 pm
Don’t want to mislead anyone, but I tried to resolve this question based on my understanding, the answer may not make sense, hope Coach or anyone else can review and verify, this is just for discussion:
Step 1, find out the maximum allowable moment:
S= M/Fb
S(section modulus) = 3.5” x 11.25” x 11.25” / 6 = 73.83 in3
so M=Fb x S =1200 x 73.83 = 88, 596 # in = 7, 383 #ft
Step 2, Find out the linear load on the beam:
M = w x L x L/8
So, w = M x 8 / 10’ x10’ = 590.64 #/ft
Step 3, based on the 80psf load, find out the spacing of joist:
Spacing = 590.64/80= 7.383 ft center to center
I really hope that I won't have this kind of question in the exam, too complicated!!