fixing a moment end plate connection in site.

[malikasal]

in one of our PEB projects, the columns were fabricated with 30mm less than the required overall depth, so now there is a 30mm gab between the end plate (welded to rafter) and the column flange.
the suggested rectification is adding a 30mm plate to act as a filler and eliminate the gab.

what effects will this plate have on the connection capacity??




ôIf you don't build your dream someone will hire you to help build theirs.ö

Tony A. Gaskins Jr.

 

[dik]

It should have little impact. Check with the PEB supplier. They are the ones responsible for changes to their building. Modifications could void any warranty.

The extra grip on the bolt could affect the torquing.

Dik

 

[Whoopdedo_LSU]

I would butter weld material to cover the gap or cut the rafter back and make a splice.

Dik is right though, it's on them.

 

[Agent666]

Depending on code, some codes have a reduction to bolt shear capacity with filler plates over a nominal thickness (6mm in the case of our NZ code).

So review if your local code has something similar. From memory the reduction is something like a fixed 15% reduction in our steel code. But usually shear is easily accommodated in end plates as bolting is primarily sized based on tension, however can be an issue as affects any tension/shear interaction in the bolts if bolts are designed to the limit.

 

[BridgeSmith]

As Agent666 wrote, there is a reduction to the shear capacity of the bolts for "filler plates". In the AASHTO Bridge Design spec, there is a formula for the reduction based on the thickness of the filler plate. I'm not at the office, so I can't give you an exact reference, but you'll have to go by your governing code provisions anyway.

 

[T_Bat]

Agreed with the above - in AISC code there are (2) options that you can apply - see J.2.(a) & (b). You can take a reduction in shear based on the filler thickness (AISC provides a reduction of 1-0.154*(t-6) where t=filler thickness is SI units). OR design the weld of the filler plate to take any shear so it is transferred to the filler plate then into the column with no reduction in bolt capacity.

If this is a moment connection - I'd also suggest the fill plate be of sufficient length and width to make sure the yield lines will develop similarly to the original design. Maybe at least match the endplate dimensions?

 

[wannabeSE]

Why not reject the column? If the depth is off by 30mm, I’d be concerned about the columns moment capacity.