Adhesive anchors for large loads? 3

[IJR]

dear pals

I use chemical anchors(those in Hilti catalogs and sometimes my own) but always use them with contempt. Bad habit, I dont like to trust them very much

Now you have a serious beam reaction and a reinforced column to attach a steel beam with this reaction to. The column is already cast and the beam is to attached at a very bad elevation from where you can see friends down below with a birds eye view(joke to emphasize importance). How do you go about attaching anchors there. Hilti catalogs would have nothing for some 30 tons(66 kips) of reaction.

I need you to share your experience on this issue

respects
ijr

 

[JedClampett]

For heavy and/or critical loads I like to use Drillco Maxi Bolts (

http://www.drillcogroup.com/index_html).

These are "undercut" anchors, meaning a special tool is required to bell out the bottom of the drilled hole. Hilti also makes a competing product.
This type anchor is very strong and reliable if installed correctly. We used them in Nuclear Power Plants for retrofits if that means anything.
I would still put in extra bolts for an extra factor of safety or in case of a bad installation.

 

[flamby]

If it is a column, can you drill through and through and install threaded rebars? It can cut your cost and worries.

Your joke was very descriptive and hilarious!

 

[IJR]

flame

Drilling through a column means chopping off some more rebars. I have used your technique many times when I have a wall or a beam to anchor to, but I am scared to death when I have to drill through a column. Where I live seismic events pop up often and columns do all the falling and shattering and remind you of each detail you have missed in your new and old designs.

Also drilling through a thick column would require one of them expensive carrots(those used to extract undisturbed samples from existing concrete) and an even more expensive guy.

Got anything else besides drilling through

respects
ijr

 

[ccw]

Hi IJR,
Is this structure like a flag pole with a cantilevered yard arm (like a street light) or can the beam be terminated with a pinned end joint? Does it have another support on the other end? I was thinking about a steel sleeve around the column where the cover takes the local compression and/or shear from the sleeve

I have seen reinf cast. columns tightly wrapped with steel wires to prevent siesmic spalling and spewing of the cover on the compression stroke. This would be taking that concept to new heights!

 

[IJR]

ccw

To further the discussion, you can go on and talk on steel sleeve around the column. What I have is a round reinforced column which I will use to support steel beams. The connection between the two is a simple shear connection, but the shear is very large.

And the column has been cast.

I have elected to use anchors with epoxy resin, many in number and spaced carefully apart, anchors will be tailor made. The anchors will attach a thick steel plate to the column and I will then weld the beam to the plate.

Threaded rebars and steel sleeve is what I have to learn a bit more about-especially the techniques used.

respects
ijr

 

[measure]

IJR,

Some of these epoxy anchors are not recommended for "hot" environments. The connection may be critical in a fire.

Regards,

Measure

 

[ccw]

Hi ijr,
Thanks for the additional information. I think the main difference between my steel split sleeve or girdle and your steel plate would be that the sleeve would distribute the 66 kip back into the column more evenly. After the sleeve is tightened around the column, several small anchors or set screws would be attached through the sleeve into the column radially, each a few inches deep into the cover, careful to miss cutting any buried rebars. This would be done just to assure that the sleeve did not slip down the column when the 66 kips was applied. Beam hangers could be prefabbed to the appropriate split sleeve pieces.

Of course, the girdle would be more expensive to make and install.

Three further questions: Are you concerned with the post-beam attachment seismic strength of the column? What is the diameter of the column? How close to the top is your beam connection?