Grade 5 Shear Safety Factor and sqrt 3

[jimrcasper]

Per my reference the allowable shear load for a grade 5 bolts is 0.4/sqrt(3)*Fu*Root area. I am designing to an ultimate loading condition (blast loading). I understand the safety factor to be 2.5 (aka 1/0.4). Is this correct, and if so where does the sqrt 3 factor represent. Thanks in advance.

 

[trainguy]

jimrcasper,

I believe 1/sqrt(3)= 0.577 is a factor generally applied to Fy or Fu to represent shear stress, as opposed normal stress.

I'll venture to say its related to Mohr's circle, but I won't attempt to derive it using basic principles...

tg

 

[UcfSE]

1/[√]3 relates the F_y from tension to F_y for shear, based on the von Mises criterion. It is not a safety factor.

This is where the 0.6 factor comes into play with shear. 1/[√]3 ~ 0.6. If FS = 1.5, the you would have 0.4*F_y, which is what we see in the old AISC ASD steel book.