So, I have a large thick (8”) concrete slab on which a metal farm type building was attached. The building came down in last years hurricane, and when it did, the end truss bases snapped the corners off the slab. Broke off a triangle maybe 24” on a side. What’s the best fix so the repaired corners have the strength to hold new building bases? Is the concrete bond going to be enough? Are there things I can do to increase he strength of that bond? Drill and epoxy rebar into the existing slab?
im not a concrete guy, but yes i believe you will need to drill and epoxy rebar in to the existing slab, and then tie it on the rebar that will be inside of your future corner pours.
JB weld and ductape you can probably put some anchors in there if you don't want to epoxy the rebar in there.
I would dig into the ground a place the columns in concrete or on a footer, then pour the broken pieces after. I wouldn't depend on a repaired floor to hold the structure of the barn. This will take the weight of the building off of the repaired concrete slab.
You had no perimeter footing in that slab? Only 8” of concrete at the perimeter? It failed for a reason. Address the failure, which I would imagine include beefing up the perimeter footing....particularly the corners where it broke loose, and then put it all back together with new steel dowels, epoxy, and possibly a rebar cage of sorts to really anchor the corners... Might not be a bad idea to consult with an engineer. Have them run calcs for you and repair according to their recommendations. That way you’ll have a record of the repair as per engineer specs.
As Rico said, it was designed incorrectly. It should have had a turn down slab. I'm working on a new building for the KY Air National Guard and I think there is an example on my drawings at the office. If so I'll take a picture and post it in the morning.
What he said. Metal building are lightweight structures. Footings are sized to resist wind uplift and moment forces. Gravity (live and dead loads) are not usually the critical load.
100% agree with above ...and if the new building is a typical pre-engineered building there are going to be considerable horizontal reactions at the bases. The metal structures do not want to stay up on their own and require a "tie" at their base. I've used up to dbl. #9 rebar connecting base to base in the past but more typical now is running 20' #6 "v's" out from the bases into the slab center. The new building shop drawings will call these loads out. Kindly disregard if not a pre-engineered building but if frost is an issue in your area you may have found the source of the failure.
Here's a page full of different concrete slab ands footer details. While none are exactly what yours should have been, A at the top left corner fits the bill closest. For buildings as you describe I've seen the A detail but it doesn't typically have the bottom spread footer part or the cold joint at the top. It would be a continuous pour with typically #4 or 6 rebar. I'd draw you the detail but it's too early in the morning Here you go...the exact detail I was looking for.
Ok, so with some digging around the corners there’s definitely depth below the slab thickness like Kelly’s drawing above. That makes the broken piece more like a three sided pyramid that broke off than a flat triangle off a slab. I assume rebar pinning to tie the corner fill-in is still the call? Fiberglass rebar work in this situation? Steel rebar out here is a problem in the making...
Pete, you might be OK with doweling. Here's a good resource to get you started...it's what we use. Might be overkill but could also be good insurance against a recurrence. https://www.hilti.com/content/hilti...n-centers/anchors/anchors-rebar-doweling.html
Pete, you might get by with less doweling if you run diagonals down from about 2/3 of the way up the corner column down to slab and anchor to the original slab securely. Both sides of the column, all four corners.
Seems like everyone agrees on the rebar doweling or studs. How about the bond itself? Are there bonding agents I could apply to the existing side to make the patch stronger? Wetter mix and vibrate it so it bites better into the old? Wet the existing side first or leave dry?
