slenderness - wood - bending

huangyhg

slenderness - wood - bending
i have a question about the slenderness requirement  for bending in ansi nds 97'... page 17
my span is 10 ft. = 120 in. = lu
member subject to bending = 2x6 = 1.5x5.5
effective length for lu/d > 14.3 is le= 1.84*lu = 220.8 in
slenderness ratio = rb = ((le*d)/(b^2))^(1/2) = 23.23
rb recommended less than 50.
@ rb = 50 a 2x6 can span 46.5 ft?????
does this sound right?
something seems off.... maybe i'm missing something.
check out our whitepaper library.
use (l/d1) or (l/d2) whichever is larger.  the slenderness ratio may not exceed 50 except that during construction it may not exceed 75.
l/d1<50    l/5.5<50    l<275 inches or 22.9 ft allowable length
a 2x6 will probably never span 46+ feet.  there's more to it than that of course.  that requirement was developed mroe for large glulam beams though it applies also to sawn lumber, according to my donald breyer book p 6.18.
thanks boo and ucf...