Checking/retrofitting existing flat slab that someone put a big hole

[AskTooMuch]

Existing flat slab (no beams) done in the 50s, supported by 4 concrete columns with capital. It was supporting an equipment. It got replaced by another equipment and someone just put holes about 2 feet dia in the middle strip, cutting rebars to allow pipe to go thru. It was fine I guess cuz it hasn't collapse. All these happened many years ago.

Now we'll be replacing this equipment again. Any good resource to check/retrofit this hole that did not have extra reinforcement per ACI?

 

[mk3223]

It was fine I guess cuz it hasn't collapse. All these happened many years ago.

IMO, for the Company's safety and operability, the concrete support might have been evaluated periodically for the operation in the past. as for the new project to replace the equipment, the structure should be reviewed per new equipment and the current Code requirement. You may review the old engineering records and to retrofit the supports as necessary.

 

[AskTooMuch]

I plan on contacting Simpson strong tie about installing something like this. But if it's not economical for this work to involve 3rd party vendor, anyone has done this kind of retrofit using steel plates hilti epoxied with threaded rod?

 

[STrctPono]

AskTooMuch,

You're on the right track with the externally applied carbon fiber reinforced polymer system. I've done this several times for holes put in bridge decks. The material is expensive (lb for lb) but overall, that will be your easiest and cheapest option. The applicator will need to be certified by the manufacturer to install their system. They will need to roughen the surface to CSP3 prior to application of the CFRP. Not sure about Simpson Strong Tie but FYFE Engineering staff can even help you design and detail it if you need help. You just need to specify their product... (I have no affiliation with FYFE or any other FRP manufacturer).

 

[AskTooMuch]

Fyfe engineering support is free as long as I specify their FRP product?

Our internal construction can't install this if they're not product certified? We've used different vendor products before (epoxy grout, hitli, etc..) those didnt require certification to install.

 

[Settingsun]

Anyone designing for free is doing it to sell their product. Their certification will state it's based on their product's parameters and void if you substitute (IME). Certified installer are to minimise their risk: installation goes bad (cost cutting customer) and the fingers point in all directions.

 

[Ingenuity]

Back in the early days of FRP in North America (mid 90's), FRP manufacturers used to provide comprehensive training for their certified applicators. Field tech's went through 1 week of classroom and field training.

Today - not so much. I did the Simpson ST training and it took about 1 hour. Wrapped a 10" carboard sono-tube and did a quick quiz.

FRP has definitely become a commodity and all (?) major manufacturers (Fyfe, SST, Sika, BASF) will sell their materials so all-and-sundry and then provide the certification as a service to the sale.

As a results some installations are considerably less than stellar.

 

[STrctPono]

Fyfe engineering support is free as long as I specify their FRP product? Our internal construction can't install this if they're not product certified?

Correct. You certainly want an experienced installer. It's honestly not that hard but there are some nuances with surface prep, saturation techniques, installation and smoothing to remove air bubbles, testing that you don't want someone that has never done it before.

Epoxy grouts understandably don't need certification. But injectable anchoring adhesives do technically require an ACI certified installer.

If you don't want to use FYFE, you can always study and learn ACI 440.2R, design it yourself and provide inspection.

Today - not so much. I did the Simpson ST training and it took about 1 hour. Wrapped a 10" carboard sono-tube and did a quick quiz

That's pretty bad! Certainly commoditizing the industry. Bond critical applications are quite a bit different than contact critical. With the introduction and push for FRP anchors for flexural applications I would think that this would keep the industry in the hands of experienced applicators. However, I was pretty taken back when I saw that Sika introduced a pre-saturated FRP. They are certainly catering to the DIY contractor. All of the specs we write require certified applicators with accompanying resumes.