AS3990 Maximum Permissible Stresses in Snug Tight Bolts

[DALOB]

In AS3990 there is a factor in the Bearing Stress calc for Max Permissible Stress in Snug Tight Bolts of 2.1. See below.


I was wondering if anyone can explain where is factor came from and why it is being applied to this particular calc.

Thanks,

Jason

 

[Smoulder]

Tests to failure. AS4100 commentary says failure is 4.5 to 4.9 because steel piles up in front of bolt before total failure. Safety factor gives about 2.1, and probably AS3990 doesn't push as hard as AS4100 because it's older working stress design code. Only 2.1 when end distance is large, about double minimum requirement. Otherwise equation underneath governs.