Pullout boxes - shear capacities 1

[Just Some Nerd]

Hi guys, having a little bit of a wonder regarding calculation of shear capacities of the reo in a pullout box is (for use in a jumpform application). Looking at manufacture's design guides are bit odd to me - for example Reid's design guide seems to dip into AS4100 bolt/pin connections by including the 0.62 factor seen in clauses 9.2.2.1 and 9.4.1, but with a phi of 0.6 which seems to come from AS3600 for fixing. I've also heard of using phi = 0.36 (I think a doubling up of 0.6 from AS3600 and some other clause regarding an additional 0.6) but nobody seems to be able to point to me where that additional 0.6 is pulled from. Using 0.36 makes enough sense to me, just would like some guidance as to where numbers are being pulled from and/or why Reid seems to mix and match.

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Why yes, I do in fact have no idea what I'm talking about

 

[sdz]

"0.62 factor seen in clauses 9.2.2.1 and 9.4.1"
Do you mean
Vf = 0.62 fuf kr(nnAc + nxAo) in 9.3.2.1 and,
Vf = 0.62 fyp ns Ap in 9.5.1

This is a factor for shear distribution over a circular cross section and is not a capacity reduction factor. phi=0.8 then applies in both cases to get the design capacity.

 

[bugbus]

The 0.62 factor is to convert the ultimate tensile strength to an ultimate shear strength, it's not related to the shape of the cross-section.

 

[Just Some Nerd]

The 0.62 factor is to convert the ultimate tensile strength to an ultimate shear strength, it's not related to the shape of the cross-section.

Correct.

Perhaps a better way to rephrase my question is more along the lines of asking what the correct value for converting tensile yield/ultimate tensile stress for typical 500N rebar compared to the 0.62 given from the bolt grades in AS4100.

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Why yes, I do in fact have no idea what I'm talking about

 

[bugbus]

For yield it should be closer to the 'theoretical' (von Mises) value of 1/sqrt(3) = 0.58, 0.6 is probably close enough.

I would not rely on the tensile strength of the reinforcement, just the yield strength.

 

[Just Some Nerd]

Thanks bugbus. I wasn't relying on the ultimate strength, it was just being used for 4100 is why I mentioned.

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Why yes, I do in fact have no idea what I'm talking about