Beam connection to corner of square tube column
Beam connection to corner of square tube column
(OP)
Does AISC have any recommendations of how to connect a beam connection to the corner of square tube column? I have a W12 intersecting a through TS6 column. Thanks in advance!!





RE: Beam connection to corner of square tube column
I've used a single plate welded to the column, like a single plate shear tab on a W column. I don't know if its aisc recommended or not. Also, I've used this on smaller beams, but I bet you could make that detail so it works.
regards,
chichuck
RE: Beam connection to corner of square tube column
RE: Beam connection to corner of square tube column
RE: Beam connection to corner of square tube column
Any eccentricities should be based on the diagonal dimension.
RE: Beam connection to corner of square tube column
RE: Beam connection to corner of square tube column
I would consider a bearing seat for erection purposes only, but not the top flange connector, as the connections at the top and bottom could impart unwanted moments to the column - unless you are trying to make a moment connection.
Mike McCann
MMC Engineering
RE: Beam connection to corner of square tube column
RE: Beam connection to corner of square tube column
Mike McCann
MMC Engineering
RE: Beam connection to corner of square tube column
What is supposed to happen when you need through plates in each direction for a tube or pipe connection? It seems to me that you wouldn't get a lot of benefit out of just running the plate with the lesser load back into the other plate and butting against it.
Answer(s)
09/01/2000
It's an amusing detail to say the least. Unless you're at the end of the HSS, I suppose you need a really short welder to crawl down into the HSS!
Seriously, though, the AISC HSS Connections Manual covers both single-plate (shear tab) connections, which are made with a plate welded directly to the face of HSS (i.e., without a slot), and their more expensive cousin, through-plate connections, which are made with a plate that penetrates the face of the HSS. It is expressed in that publication that the conventional single-plate connection should be used whenever possible. The design procedure covers all limit states, including those to ensure that the column face is adequate without the need to extend the plate through the wall and make it a through-plate connection.
Through plates are expensive because they are difficult to fabricate, so avoid them if you can. And you almost always can. Avoid them especially when opposite through plates would intersect each other inside the HSS. If the plate isn't continuous to the other HSS wall, I can't see what good it does to extend it inside. It may actually do harm since you would have to hack up the wall of the HSS to make that kind of connection.
Charles J. Carter, SE, PE
American Institute of Steel Construction
Chicago, IL
RE: Beam connection to corner of square tube column
The HSS Connections Manual indicates that a single-plate shear connection can be used if the following HSS wall slenderness ratios are satisfied:
1. Rectangular tubes: b/t < 253/Fy0.5
2. Round tubes: D/t < 3300/Fy
Are these limitations alone enough to satisfy the requirements or must one also evaluate the wall for punching shear resistance? Do the HSS requirements also apply to ASTM A53 steel pipe? How about to large-diameter round and large-sized rectangular HSS?
Answer(s)
As noted in the HSS Connections Manual, the slenderness limits assure that local distortion caused by the shear tab will be insignificant in reducing the column strength of the HSS. However, even when the slenderness limits are met, there are HSS wall limit states that should be checked. See Table 4-2 for the applicable limit states (shear at weld and punching shear.) Table 4-3 gives the rationale behind the limit states.
The HSS Specification (Section 1.2.1) specifically lists ASTM A53 steel pipe as approved for use under the HSS Specification. As such, the HSS equations are applicable to ASTM A53 steel pipe. The HSS Specification also applies to the limits of ASTM A500—a maximum periphery of 64". For example, a rectangular HSS 20x12 is right at the limit. Also keep in mind that as you get bigger, it does become more difficult to meet the slenderness requirements about which you asked.
Keith Mueller, Ph.D.
American Institute of Steel Construction
And another:
Which is more economical to specify—shear tabs or through-plates when connecting a wide-flange beam to a HSS column?
Answer(s)
Conventional shear tabs will almost surely be less expensive than through-plates. The main issue is the cost associated in making through-plate connections compared to using single-plate shear connections on both sides of a tubular column. The best way to confirm this is to ask your fabricator for a comparison quote. In general, through-plate connections are not the preferred shear connections for tubular columns because of fabrication cost. Note that through plates may become necessary if the HSS wall is slender or if the punching shear limit state requirements are not met.
Sergio Zoruba, Ph.D.
American Institute of Steel Construction, Inc
RE: Beam connection to corner of square tube column
RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke
RE: Beam connection to corner of square tube column
RE: Beam connection to corner of square tube column
In case the connection attracts bending moments and axial force, with/without the column is having the similar actions on the other sides you may need to think about how the load paths are to be. Sometimes you may be forced to cut off the connected area of the column and replace with properly designed column piece integrated with connections. When this is required and concrete filling is essential, you need pay attention to any detail.
Load path at the connections which includes the plate surfaces of columns are very important, whoever selects the connection and make decisions on the entire system this has to be the focus at front.
Hope it helps
Ibrahim Demir
RE: Beam connection to corner of square tube column
RE: Beam connection to corner of square tube column
RE: Beam connection to corner of square tube column
You need extend the column leave some distance ( at around width of the wall ) to get this flexibility required and close the top of the column with a plate. Or you need to design the beam depth not to introduce rotations ( or introduce for very small rotation) at end connections. This option might be expensive due to the large depth calculated for the beams.
The flexible end connections were given for a limited rotation at connections, and this rotation needs to be checked for each application normally. However, I often see that they are mostly ignored by engineers unfortunately.
While the connection rotates it pulls the top of the connection and push the bottom into the column and the wall change the shape, deflects within the yield criteria (yield line analysis), and restrained by the perpandicular walls. Therefore, you need to control stresses within the hook law or allow some yielding. All these are the design issues you need to go through.
Hope it helps.
Ibrahim Demir
RE: Beam connection to corner of square tube column
When worrying about distortion of the tube wall, as long as the tube wall is not a slender element and you are not detailing for moment connections you should be ok (see page 10-158 and 1-93 of 13th AISC Manual). In any case, I doubt that a 6x6x1/4 tube has enough stiffness to attract significant moment, and I assume that your beams have been designed as simple spans.
I am concerned about a couple of issues regarding your detail. With a 6" tube, it will be difficult to get weld on the double angles where they meet the tube because of the corner radius of the tube. I think this detail may be difficult to construct. In the 13th AISC Manual they tabulate values for workable flat dimensions. As long as the tube wall is not a slender element, you can use a shear tab connection, which would be easier to fabricate, see page 1-93 of the 13th AISC Manual. If you stay within the guidelines of AISC, you should be fine with single plate shear connections and not have to worry about yield line analysis.
Regarding the beam comming in to the corner of the tube, I think this would be a very difficult to slot the tube at the corner. I recommend a bent plate welded to the wall of the tube and then you can bolt the outstanding leg to the beam web since this is much easier to fabricate.
I don't know what your loads are or what the unbraced length of the column is, but a 1/4" wall thickness seems a little on the thin side. With complicated connections, I would recommend 5/16" minimum.
RE: Beam connection to corner of square tube column
Moving on then...My involvement was detailing the beam and column lengths and the connections. My direction was "design the connections for A325N bolts to develop half the maximum beam shear per end." I assumed from this that the connections were from simple beam analysis.
I have sent the architect (and I hope he sends to the engineer) questions regarding the overall stability of the framing and the lack of rotational stiffness in the connections, particularly at the column tops.
I was hired by the fabricator who chose the slotted detail. He's making the parts in the next few weeks so we'll see how wisely he chose.
The angle clips are 2 1/2" x 3 1/2" x 3/8" 6" long. I'm asking the fabricator to weld three sides of the angle clips - top, side and bottom. Neglecting the vertical side, there could be 5 inches of 1/4" weld for each angle but if I count on only 8" total I would expect those 8" to hold about 32kips. The maximum shear per beam end varies from 18.5 to 35.5 kips. We added beam seats for the 35.5 kip loads.
All in all I think we will be OK but I'm looking forward to the architect / engineer's review of my drawings.