Clamp connection

[Joeymin]

Hi all,

I would like to calculate for clamp connection detail as I attached. But I dont know where to start. Could somebody help me?

1. Plate thinkness
2. Bolts

Have a good day.

 

[Agent666]

I don't think you uploaded the right attachment? (it appears to just be a floor plan?)

 

[Joeymin]

Sorry. I uploaded again.

 

[Agent666]

Have you looked at lindapter clamps, these appear to do exactly what you are after but are a commercially avaliable solution and have been tested and have design capacities. Likely cheaper and more reliable than trying to fabricate something yourself. Saves you some design time also. They are more or less avaliable world wide.

 

[Joeymin]

I know. My client has this materials and design from Korea. They just wanted me to check it is workable here in USA.

 

[Agent666]

Well the obvious point is the fact that there is nothing retaining the brackets/bolts onto the flange. There's no real clamping action like the lindapter clamps or a common plate between the members like the lindapter ones to retain the bolts relative to one another.

For example if the round bar is larger in picture what would occur, the clamping of the top plate would pivot down & be based on a knife edge, similarly if the round bar is too small or if you tighten and deform plates it could only bear on the flange edge. There's no details of what is welded /connected to each other, so it's hard to say otherwise how it's intended to work.

If in doubt you are allowed to say no. I personally can see issues with the concept without even throwing any numbers at it. So that alone makes it a no go in my opinion.

 

[Ron247]

I have done similar connections in the past. I am not addressing the load magnitude or specifics of your situation. In your detail, the bolts are too far away from the beams. Typically, we tend to put the bolts almost against the flange. The bolts will have an eccentric load that creates bending in the bolt. The farther from the main steel, the more bending you have. The Sx of a bolt is not much. So even an extra 3/4" of arm is a big deal.

I tended to use a single plate across the entire bottom, not 2 independent pieces. Then I attached whatever I needed (the W8x40) to the solid plate. Your 2-piece setup bothers me.
In my method, the single plate is made the same width as the WT flange, therefore minimizing the eccentricity. In your 2-piece system, the moment arm on the WT is still large because your W8x40 flange is so much wider.

I too recommend Lindapter, but if you must make you own, be very cautious. Years ago they were using these all over a local plant and someone told the contractor's to do it like this and handed them a drawing someone else created for a specific case. Just like yours, it showed the bolts being 10" apart. That is what people used even when the flange was only 6" wide. This leads to a huge moment arm on the bolts. The detail was correct for its original application, but not for all the new applications that came along. The reason I know is that I was handed the same detail and told to use. I did not use it as shown but made my own. I made sure mine showed the bolts relative to the edge of flange and not center to center. I used a single plate as their example did, but mine was thicker. I saw several in the plant that were not my responsibility that had almost a 2.25" arm from edge of flange to center of a 3/4" or 1" bolt. Luckily, most were not that heavily load.

 

[oldestguy]

What's wrong with just bolting the flanges together and no plates. Maybe with washers?

 

[Ron247]

I asked the same thing years ago and was told the original designer of the building would not allow any altering of the bottom chords. They knew future loads would be attached to the bottom chord. They would only allow clamp loads and that is it. These loads may be present for 3 years and the entire hanging gizmo may be taken down and replaced with a totally different one. Eventually, someone would have torched, welded, slotted or damaged the bottom chord over time.