Beam To Beam Moment Connection ??

[TekEngr]

I have a 1.5m overhang with concrete and decking sheet. Main beams and secondary are on same level so moment connection needs to made between the main and secondary beam (Cantilever Structure.jpg). I have two options for connection.
1. Fin plate in between and flat plate on top and bottom (Con type-1.jpg)
2. End plates on both sides (Con type-2.jpg)
Is the behavior of type 2 connection same as type 1 ??
I am using IDEASTATICA for analysis of connection and both are working.

 

[CANPRO]

Can you shop weld the overhang side to the main beam? Are you the steel fabricator on this job? If so, I'd check to see what the preference is for erecting the steel...either option can be made to work, but there might be some external factors which would drive the choice of connection type.

 

[WARose]

I've typically done "Option-02".....with a couple of differences: cope the web back to where that end plate isn't needed (i.e. it connects direct directly to the girder web with a standard clip angle connection (welded to the girder)) and I do the same thing on the other side (as a means of taking out the torsion; unless you are accounting for that another way). And I do a full-pen weld (flange to flange; in the field) on both sides of that girder.

 

[CANPRO]

I think the bolted flange option is probably cheaper as it avoids site welding. Also, if your beam sizes aren't the same it can complicate the flange to flange weld.

Another thought on cost saving measures - depending on the loads and your girder capacity, you might be able to get away with a backup moment connection on every 2nd beam instead of every beam. If you only have a few of these, probably not worth it, but if you have dozens of them it might make sense to look into it.

 

[DenverStruct]

Are you sure you cannot put the orange beam below the blue beam?

 

[dik]

Canpro's suggestion if common with the 'stubs' welded to the beam and the back span beam designed for the moment connection... also seen the backspan beam flange butt field welded to the main girder. Normally no need for CJP welds.

Dik

 

[mike20793]

I'd want all my weld thrus to be complete pen welded, even if something else would work. Use the plate if you can, but complete pen weld thrus are common in my area.

 

[WARose]

I think the bolted flange option is probably cheaper as it avoids site welding.

I agree....but I suggested the second option because I thought "option 01" would created a problem as far as top of steel (TOS) elevation goes. Not sure if the concrete guys could address this while forming.....but i've never had deck sitting on something like that before. (I.e. the bolt heads.)

 

[dik]

I'd want all my weld thrus to be complete pen welded, even if something else would work.

You pay quite a premium for that, in particular, if they are field welded. Your seal, your call...

Dik

 

[mike20793]

That's true dik, but I agree with WARose. Most often the plate will cause a conflict with top of steel and composite deck or joist bearing or something else that's usually not worth coordinating out. If you can make the plate work, by all means do it, but in my area, the common detail is all welded, especially if the deck is being attached directly to the beam and girder.

 

[TekEngr]

Site welding is difficult due to some reason.
I am also intrested in option 1 but only issue in this connection is top bolt head,  these bolts head will creat problem at site for fixing the floor decking sheet.
Any one can suggest how i can fix decking if i choose option 1??
Floor Decking is 65mm thick and sheet rib height is 22mm.

 

[CANPRO]

Bolted flange plates are a fairly common detail, the deck issue must have been dealt with before...but to be honest, it’s not something I’ve given much thought to. I’d think the deck would roll up and over the plates/bolts fairly easy in the weak direction of the deck. I suppose you would lose a little bit of concrete cover at that location. With 22mm deck and 65mm of concrete it shouldn’t be too much of an issue.

What is the design moment? You might be able to use a reasonable size flush end plate - beam has an end plate and a short section of beam is welded to the main beam with an end plate.

If the overhang is only 1.5m, you should be able to shop weld those to the main beam.

 

[spieng89]

I lean towards canpro in that top bolts shouldn't be that much of an issue for the deck to go over especially since according to your pic the flutes would be running perpendicular to the connection and there is a good chance the bolts would be within the flutes. If not the ~3/4" push up should affect the deck too much

 

[Mjkkb2]

In my market the standard would be a combination of the two - shear tab/plate with bolts for gravity and a full penn direct weld of flanges for the moment. Not the most economical for sure but common and works well. I thick either one would be acceptable with option 1 to be the most economical. Especially since judging by only 4 bolts being needed to develop the flange force, the full penn weld's capacity wouldn't be utilized.

 

[T_Bat]

I have designed flange plated connections where we weld a deck support plate to the underside of the bolted flange plate or butt welded to the beam flange. Nothing big - 1/4" thick with at least 3" of overhang to give deck bearing and a place to attach down to.