Beam-Column Constructability - Base Plate on Both Ends

[Redacted]

Hi there,

I am thinking through a steel beam-column detail that will be anchored to baseplates on both ends.

From a construction point of view, I am trying to visualise how I can get it to work.

Essentially if the contractor installs the post-installed anchor bolts on both sides there won't be enough space to fit/slide the beam in.

In situations like this, is the construction sequence as follows?

- Contractor marks anchor bolt locations on both sides
- Contractor installs the post-installed anchor bolts on one side only
- Steel beam with the base plate pre-welded is lifted into place
- With the steel beam in place, the contractor installs the post-installed anchor bolts on the other side (which would require injecting the epoxy through the baseplate hole and inserting the anchors through the base plate holes?)

Is this a fine approach or is there a better way to construct this or a detail that I should be considering to counteract this issue?

I built in about 4" of tolerance into the placement by including an allowance for 2" grout on either side, although this isn't enough tolerance to avoid clashing with the anchors.

The beam-column is subject to quite a high axial force.

 

[MIStructE_IRE]

Can you do an end plate one end and a pocket detail on the other? Pocked can be grouted up once beam is installed.

Since you have end bearing on both ends, what are the bolts doing anyway?

 

[Redacted]

Hi MIStructE IRE,

The beam-column is more on the column side taking an axial compression load of 1120kN.

I guess the purpose using the HILTI anchors was to mainly just keep it in place during construction and to provide redundancy in case the build-out failed.

I had applied a tolerance eccentricity of about 50mm to the axial force and applied that as a moment to the end connections as well, which I had designed the anchored base plate connections for.

Although now you have me wondering if that was necessary and if it would just be easier to encase the ends in concrete...

 

[MIStructE_IRE]

Sorry.. i misread it and thought it was just a beam!

In that case I’d probably insist on your currently proposed detail too depending on how the axial load is transferred into the beam. If there’s any way you can do a pocket on one side then it would be more practical to build.

 

[271828]

I'm assuming the axial force is always compression.

The sequence seems feasible to me. I would make the base plate holes larger than normal to make the second set of adhesive anchors easier to install. Use plate washers with standard holes; if there is any member end shear, then weld the plate washers to the base plate.

 

[Redacted]

@MIStructE IRE thanks

@271828 Yes the strut should always be in compression.

Good point about the oversized holes.

 

[dik]

The grout works fine... for tighter fits, I often include steel shim plates for steel to steel tight connections.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

For post installed anchors, you don't need much clearance... if preinstalled then the oversized holes help as well as making sure the anchor rods are weldable.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dhengr]

Redacted:
I’d cast thick/stiff mounting plates into the faces of the conc. walls. These would be designed to take all of the reaction forces and moments from the end plates on the beam. And, they would either be tapped for the beam end bolts, with sufficiently long threads for the bolt loads, or they would have sufficient matching nuts secured to their back sides (within the conc. wall) to accept the bolts from the beam ends. A reasonable beam length tolerance could be made up with some shim plates to fill a small gap in length.

 

[rather_be_riding]

Mounting plates as per above would assist or you could use threaded inserts like the Hilti HIS-N products. Cast them in, come along and drop your beam in and bolt it up. Simple.

 

[Ingenuity]

I think the OP's situation is that the concrete walls are EXISTING, so cast-in plates are not an option. OP to confirm.

 

[rather_be_riding]

@Ingenuity - very possible. I wasn't entirely sure on that point myself. Post installed threaded inserts will still work in that case though.