Gr. 8.8 Bolt Strength
Gr. 8.8 Bolt Strength
(OP)
Can someone tell mee the strength of Gr 8.8 bolts (BS 3692)? I'm looking for ultimate, yield, and shear strength.
Thanks,
Chris
Thanks,
Chris
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RE: Gr. 8.8 Bolt Strength
The grade 8.8 tells you the yield strength and ultimate stress, it works like this:-
multiply 8*8 then * 10=640N/mm^2 yield stress
multiply 8.8 *100 = 880N/mm^2 tensile stress
regards desertfox
RE: Gr. 8.8 Bolt Strength
Sorry the last equation should have been the first number 8
multiplied by 100 to give the ultimate tensile strength
ie:- 8*100= 800N/mm^2
Both these values are ie yield and ultimate tensile are minimum values.
In addition the yield stress is the stress at a permanent
set limit of 0.2%
regards desertfox
RE: Gr. 8.8 Bolt Strength
RE: Gr. 8.8 Bolt Strength
It is normal to assume about 70% of the ultimate tensile stress for the shear stress.
regards desertfox
RE: Gr. 8.8 Bolt Strength
Is the mm^2 the nominal bolt dia, or root dia of the thread
Regards
pat
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RE: Gr. 8.8 Bolt Strength
I haven't got the correct BS spec in front of me now, but
yes I think its based on the root diameter of the thread as
that would be conservative for design calculations.
In fact all the design calculations relating to tension that I have seen are based on minimum root diameter.
regards desertfox
RE: Gr. 8.8 Bolt Strength
Surely an allowable shear stress of 70% x ultimate tensile stress is much too high. This 550 N/mm2.
Generally, the shear stress is equal to 60% x yield stress. This gives a shear stress of 375 N/mm2. This stress only applies to factored loads.
If using unfactored loads, I would use half this valus, 185 N/mm2.
Regards
RE: Gr. 8.8 Bolt Strength
linslade is correct the value I quoted would be the ultimate shear stress not the normal working shear stress.
regards desertfox
RE: Gr. 8.8 Bolt Strength
corus