Bolt Pull Out from a plate (simply supported)

[strainstress]

Hello,

I am trying to figure out the maximum load I can apply on a bolt (3/8"-16 A325) in tension. The bolt is located at the center of 30" x 30" 1/4" thick simply supported steel plate. I do not care if the plate yields, as long as the bolt can take that load. What all failure mechanism should be considered for the this analysis ? Is only checking for the "bolt pull out" (shear strength*Pi*D*t) adequate for this analysis. What about the local yielding that occurs around the bolt hole. Does that local yielding reduces the bolt pull strength. How do I consider that effect in the analysis. (Since the roark's book only considers elastic analysis, using roark's forumla for concentrated load will be too conservative in this case).

Thanks alot for your help.

StrainStress

 

[cliff234]

First off, I never heard of a 3/8" diameter A325 bolt. (I have specified 1/2" A325 bolts but those are pretty uncommon as well.) Second, I never heard of the pullout limit state that you are referring to. "Pullover" is a limit state that is checked when checking tensile strength of self-drilling screws through cold-formed steel, but I've never checked pullover in structural steel connections.

 

[bkal]

I am not sure why are you checking shear strength*Pi*D*t, especially if bolt is tension - unless you are trying to check 'punchng shear' of the bolt head or the nut but I have not come accross it (I do not work in the USA); it seems as if you are trying to check thread stripping, but it should be done differently. Yielding of the plate would affect capacity of the 'assembly', and this is something that could be checked if the bolt is in tension (fan-type yield line pattern might give an estimate of the capacity).

 

[fegenbush]

cliff234 is correct. ASTM A325 does not cover 3/8" diameter bolts.

Even if you are not concerned about yielding of the plate in question, the load on the bolt will cause a prying action that will act in combination with the shear at the bolt hole. AISC 360 covers this in Chapter J. Also remember that the root area of the bolt will limit the allowable bolt load due to the reduced cross sectional area.