Hollo-Bolt Experiences/HSS Splice

[bookowski]

Anyone out there using the Hollo Bolt from Lindapter or the shirkun concealed nut system for splicing HSS and have any + or - experience to share? I've got a very long and heavy HSS beam that has biaxial bending and a little torsion that needs 2 splices of with minimum protrusion. The contractor is asking about this option in lieu of a welded solution.

 

[KootK]

Given that these will be site made spices, does that mean that you'll need slotted bolt holes for tolerance / fit up and, therefore, slip critical bolting? Or is this a thing where it can be assembled on the ground and tolerances can be provided at the member ends?

Lindapter's website suggests that they'll attempt the connection design for your. If time permits, that might be a good place to start.

[sub]That's a horrible idea. What time?[/sub]

 

[bookowski]

The tolerances are at the ends. It's very lightly loaded but still a massive long section. This is one of those annoying big slider systems that want near zero deflection. Fixed glass sits on top but otherwise there is no load. So the demands are relatively light compared to the size, it's all deflection driven.

These look good, as does the shiruken. I'm wondering if they're being used in the wild though and if anyone is having issues.

 

[KootK]

Hollow Bolts certainly get used in the wild. I can't comment on the Shiruken given that this is my first time hearing of them.

Given that this is deflection sensitive, I would think that you'd want;

1) Slip critical bolting or at least the equivalent pre-tensioning or;

2) A plan to preload the joints prior to installation of the glazing to take up any bolt hole slop.

So I'd be be keen to check in with the suppliers to verify whether or not these things can be used SC. Any angular change in the members at the splices under load may well telegraph as unwelcome vertical deflection.

The hollo bolts seem to have a version that is "High Clamping Force". I like the sound of that, even if it winds up being sort of a DIY version of SC from a deflection perspective.

[sub]That's a horrible idea. What time?[/sub]

 

[XR250]

Couldn't you cut a window in the top of the beam at each connection to allow conventional bolting? Sounds like the stress is not too high.

 

[XR250]

Have any of you put a trailer hitch on a unibody car? They typically come with these cool wires with coils on the ends for fishing the bolts thru. Would not need much of a hole to use this system.

 

[bookowski]

I've reached out to hollo-bolt to get more info. For the High Clamping Force version they don't give much info other than a graph showing it's clamping force vs the regular version. I agree that given the deflection sensitive nature I can't have any slop (this is a continuous 2 span slider system, 40ft and 20ft so slop would add up quickly).

A window probably is possible. It's a 16" HSS so plenty of room for an access hole. I don't know that the fish wire would work for the vertical bolts, or at the very least it's a little tricky. Once you pull the bolt through you need to unthread the wire without the bolt dropping back down, and then hold it while you get the nut on. You'd probably lose a few to the internal hss graveyard.

The nut keeper system looks like it may be the way to go, you get all the standard aisc bolting so no relying on tricks.

 

[XR250]

I imagine you would lose a few but so be it. Mechanics magnet on a stick is helpful for holding the bolts or just jamming a screwdriver into the side of it.

 

[milkshakelake]

If your HSS is exposed to weather, the Hollo-Bolt can introduce water leaking into the beam. You can drill some weep holes into the bottom of the beam.

 

[Agent666]

The Lindapter hollo-bolts also need a 0.5mm larger hole than the fixing to be installed correctly, it's related to getting the splines to grip and not having the bolt just spin in the hole. So if site splicing and tolerances are critical you may be pushing things to get that type of precision.

The other thing is for a certain sized bolt, generally the hole required in the steel is much larger than the called-up bolt size due to the nature of the sleeve over the bolt. So this specifically needs to be taken into account with respect to the loss of the cross-sectional area for member design, and spacing and edge distances for detailing the connection.

https://engineervsheep.com

 

[azcats]

The Nexgen2 is another blind bolt with ICC ESR evaluation. Different mechanism than the hollo bolt.

I don't suppose these HSS are large enough to add a hand access hole and put bolts inside on an interior flange? I saw that once on some large diameter (30" IIRC) pipes and it worked pretty well in the field.

 

[MegaStructures]

I've used Hollo Bolts several times; the steel workers have hated them every time. Welding seems to be the preferred solutions for the workers I've asked that have tried both. It's unfortunate, because I think the Hollo Bolts are pretty cool, I was excited when I first found them, since we have to splice long spans of HSS often.

Windows for standard bolts sound like a good practical solution. I have considered doing that myself, but don't feel that I am smart enough to determine the reduction in member capacity caused by adding the window...

“The most successful people in life are the ones who ask questions. They’re always learning. They’re always growing. They’re always pushing.” Robert Kiyosaki

 

[GC_Hopi]

MegaStructures: My experience has been the same as yours. Contractors simply refusing to use Hollo Bolts but wanting to field weld every where and everything. Often the excuse is "they are out of stock" then I call the sales rep and they say we have those in the warehouse across the street from your project.