HSS Column / Chord Splice

[TTUengr51]

I'm currently working on a 160' tall lattice tower structure that is to be constructed of HSS shapes. The tower is similar to the towers used on a free-fall amusement park ride.

The dilemma I'm having at this point is my main column splice. Since it is a tower structure, the columns are seeing both high compression and tension loads. One of my design goals is to keep the outer faces of the structure clean, thus I cannot use an end plate connection. Welding is not an option either since erection speed is a priority, and I'm concerned about weld quality in the field. I've considered an interal splice plate and putting field installed bolts in shear, but am getting a large amount of bolts. This connection is a concern due to the possibility of excessive "play" in the connection.

I've seen some pictures of a similar structure in which a large steel block is attached to the two interior faces of the tube and high strength bolts connect the blocks in tension. My concern with this connection is the tension stress concentration on the two attached faces and any eccentricity this would placed on the tube. It's basically an asymmetric end plate connection.

At this point I'm hoping to get any ideas or suggestions...your help will be greatly appreciated!

 

[EdStainless]

It would be good to see a picture.
The system that I ahve seen used involves shop welding (and inspecting) special end pieces to the column. The end pieces are preped for connection. Yes, it takes a lot of bolts. Load distribution, torsional loads, saftey factor, all add up to a bunch of hardware.

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[TTUengr51]

Thanks for the reply.

 

[TTUengr51]

Here's a link to the picture I was trying to describe above.

http://home.comcast.net/~ridgetopphoto/Wonderland_Tower3.jpg

Thanks

 

[EdStainless]

I am guessing that the tower in the picture has solid fill in the ends of the tubes and large pins in them. This would carry the load, the bolts just keep the joint together.

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Rust never sleeps
Neither should your protection

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[TTUengr51]

I'm not sure I understand by the large pins. You're saying that the inside of tubes are filled solid, but I don't get where pins come into play. It looks like to me that the only thing fastening the joint together is the 4 bolts on the 2 exterior faces of the tube.

 

[gtaw]

I've seen splices similar to this on towers of tower cranes. The HSS usually have plates welded inside the tube. The lower tube has a plate and pin that fits into a hole in the plate of the upper tube. The bolts, four per vertical HSS column, resists the tensile loads only. The pin and sockets resist the torsion loads and the plates, beside securing the pins and sockets, resist the compression loads.

Best regards - Al

 

[EdStainless]

Thanks GTAW, I wasn't very clear.
Crane towers, I knew that I have seen these somewhere.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[TTUengr51]

Thanks guys for your help!

 

[csd72]

Or just make the horizontal brace members big enough to take out the eccentricity in bending.