Hello everyone,
I have a question regarding through-plate connections on square tubing (HSS). In order to have this type of connection, a slot must be cut on the piece of material. The slot must have perfect rounded ends. This is usually accomplished by either drilling one hole on each end of the slot, or thermal cutting. I have seen this done also by cutting it by hand with torch and then using a pencil or dye grinder to smoothen the ends. Usually, once the plate is put through the slot, the plate does not fill the entire slot. In other words, there is an empty space, where the radiuses of the slots are. So we have four radiuses once the plate is through. The connection then gets fillet welds on both sides. My question is this, is there any information anywhere that says is it necessary to weld the radiuses? Does the plate has to be welded all around, or can the radiuses be left open? I know many places leave these areas without weld for two reasons. One is because the the welding symbols is only for fillet welds on both sides, and not all around. Two is because if welded it may create undercut on the corners. To weld or not to weld?
Any imput is always appreciated. Thanks.
Ram_
Hello Ram, when Safeco Field was built in Seattle, WA. there was a lot of concern and talk about wrapping the ends of connections similar to those you are describing. Many of the subs on the project were told to wrap and others weren't. I do not know if they ever really decided one way or the other. I do know that there was concern with having stress risers that would promote cracking if the corners(ends) were wrapped. I know this response may not have helped you directly but it might shed a little light on the reasoning behind why some of the fabricators weren't wrapping corners. Good luck and I'll be interested to see some of the other responses. Regards, aevald
I've never heard of this practice, but to answer your question, I would think that it would be the EOR's decision. On all structural jobs I have fabricated in my going on 31 years that have had through plates, we've never radiused the ends of the slots. We square cut the slots 1/8" longer than the plate at each end and weld the plate all around. We don't have any problems undercutting the edges of the plate. Slotting tube walls is an absolute last resort for us. There are other less expensive ways to make the same connection. We always wrap corners when we use through plates, but we never wrap the corners of a standard shear tab unless it's galvanized. We always carefully check for undercut, but it's not been an issue.
We have done as Scott described. Usually only pierce the tube wall just enough to get the plate through...no oversizing of the slot.
Hello Gentleman,
I came across some information on the AISC LRFD Specifications for Steel Hollow Structural Sections, Novemeber 10,2000, pg 27, section 2.
Design requirements
2.1 Effective Area of Tension Members
Single gusset plates are welded in longitudinal slots that are located at a centerline of the cross-section. Because welding around the end of the gussetplate is not recomended, the net area at the end of the slot in the HSS will be less than the gross area, as illustrated in Fig. C2.1-1
As you can see, it is not recommended. But it does not mean it can not be done. At the same time, I have not been able to find exactly why is not a recommended practice. I will keep you posted. Thanks
Almost universally here the slot dimensions are given on our drawings as larger than the through plate; large enough that welding is not possible. We get a reasonable radius but not necessarily a semi-circle. We burn without drilling the ends of the slots. We weld each side but do not wrap the ends. Never been an issue as far as I know. Have I missed something somewhere in D1.1 or AISC documents? I will follow this thread to see what you guys think.
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