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MT-TL tension pull out and shear slip resistance

Posted by Tony Hover 2 years ago
MT-TL tension pull out and shear slip resistance

Hi,

I'm looking at using the modular MT systems, and I came across the MT-TL twist lock and bolt for channel system (attached). In this catalogue, the ASD design limit for tension and shear are 1125 and 1010 lbs, respectively (for MT-TL M10 OC). Just wondering if these actions should be combined, because the bolt shaft itself is much stronger, and from a design perspective, I want to confirm if the tension pull out and the shear slip resistances are independent, and therefore does not need to be checked in combination.

For example, if my demand on these bolts in tension and shear are 1000 and 900 lbs, the tension and shear capacities are acceptable ( 1.0 (Fail). Just want to confirm that the latter combined case does not need to be applied.

Thank you.

twistlock,MT-TL,Strut
Support Systems file 0
MT-TL tension pull out and shear slip resistance.pdf492.84 KB
2 Replies
Posted by GHINA KABBARAover 2 years ago
Hilti Verified

Hi Tony,
The tension and shear allowable loads would need to be combined to check the capacity of each component separately. If the twist lock is not within the allowable limits the system might fail regardless of whether the bolt itself fails or not.


Combined loads check,Modular support system
1 comment on this reply
Posted by Tony Hover 2 years ago
Hi Ghina, thank you for your reply but just want to follow up with a question to confirm as I'm still unsure if this is the case. Just want to confirm if the shear in slip and the tension pull out for the twistlock are independent of each other. My assumption is that the pullout would increase the grip/friction between the twistlock and the strut channel, thus the slip in shear should be better, would it not? For example, for MT-TL M10 ASD (page 51 of the Modular Support Systems Technical Guide), tension pullout is 1125 lb, and shear is 1010 lb. In the catalogue, it's not asking to check the combined capacity, it simply provides a table with the shear and tension. If my tension load is 1000 lb and the shear load is 900 lb, is it therefore acceptable? If we do have to use the combined action, it seems a bit too conservative and I'd opt to choose another system over the modular system with twistlock.
Posted by GHINA KABBARAover 2 years ago
Hilti Verified

Hi Tony,
Would you mind sending us an e-mail at CA.EngineeringTechnicalServices@hilti.com so we can assist you better.

1 comment on this reply
Posted by Tony Hover 2 years ago
Thank you and happy new years