Hidden HSS Connections

[RFreund]

What are some options for hidden HSS round connections?
I have a long run of 10" diameter round HSS that I would like to be connected to make a continuous member. This will be exposed steel and I have the impression that the Arch does not want field welding to be visible, but they do seem open to some sort of cover/access plate/hole. Will the field weld really look that bad? I could design the HSS to be hinged at the connection if that helps my options. What are some options for this situation, can some sort of insert or sleeve be done?

Thanks!

EIT

http://www.HowToEngineer.com

 

[JAE]

I'd think you could do a full pen weld and then have them grind it smooth on the outside. Wouldn't that work?

 

[msquared48]

You would have to use section of a smaller pipe as an inside backer bar if you do full pen.

Mike McCann
MMC Engineering

 

[connectegr]

You can use PJP or CJP welds. The erector should be able to provide AESS welds. What are the paint requirements?

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[RFreund]

I'll look into the paint requirements. How does this affect things?

I would have thought that PJP or CJP as you guys have suggested would be ok. I mean I don't think it would look that obvious or bad.
Are there other alternatives?

EIT

http://www.HowToEngineer.com

 

[connectegr]

The welds can be completed and ground smooth. The paint system required may have some problems with touch up. For example if the is a powder coating, field repairs are difficult to match.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[steellion]

I've used CJP welds grinded smooth on AESS HSS members several times. If you have a good welder, the end result looks good and should satisfy the architect. It's the most expensive option, but you will barely be able to notice the weld in the field if it's done correctly.

 

[dik]

I usually design HSS to 70% or 80% and then don't use CJP's... generally more economical.

I also generally provide fillet welds to 1.1 x thickness for smaller tubes... greater than code allowance, but CIDECT has info that indicates that this nearly provides CJP strength.

Dik

 

[ameyerrenke]

Short of field welding which should be able to be done and ground smooth. Plates can be welded onto the interiors of the Tube, with access holes to allow the plates be bolted together. If you can get away with a pinned connection, you could use plates connected with "box-bolts" to take the shear, this would not require any access holes, but would have the bolt heads visible. Theoretically you could do a fixed connection with the box-bolts, but it would take a lot of them, and may be more objectionable to the architect than other previously stated options.


If it was my project, and it required the cleanest aesthetic, I'd do the plates welded inside the tubes then bolted together (mainly because I have a bias against field welding), but

 

[MikeHalloran]

Show the architect a standard weld neck bolted pipe flange.
Better, drop one on his or her desk.
Then (s)he may be more amenable to a few exposed bolt heads retaining an internal doubler.





Mike Halloran
Pembroke Pines, FL, USA

 

[RFreund]

Thanks for the ideas.
Not sure which way will we end up going but atleast I've got some ideas. I realize now that there will be a fair amount of torsion on the pipe as well which my make internal plat and bolting more difficult than I previously realized.

A couple of follow up questions:

If your going to put in an access hole, you would still have some sort of visible interruption of the surface of the HSS; so from an aesthetics point of view isn't this the same as having a weld there? (Sure this is probably a question for the Arch)
If the weld and the access hole are the same aesthetically and say welding or an internal plate / bolt connection were possible, I suppose it comes down to cost. Any ideas on which is more costly (welding vs internal plate/bolts)?

Is it possible to use a sleeve which fits inside each pipe and is then "box-bolted" or maybe even slot/plug welded? I could see this being semi difficult to align in the field, maybe.

Thanks again!

EIT

http://www.HowToEngineer.com

 

[ameyerrenke]

As far as aesthetics, ask the architect, he may be able to give you the direction he wants very quickly.

As far as cost, its highly dependent on if most of the parts are pre-fabbed and bolted on site, or if there is going to be a welder on site already. If this connection is the only one a welder is coming on site for, it would be very expensive. Otherwise there is less material involved so it could be cheaper if a welder will already be onsite. You'll have to consider coating/painting as well.

I think all of the options are going to be semi-moderately difficult to align in the field. An experienced installed should be able do them with minimal issue though. I'd lean away from the sleeve personally.