Threaded rod vs Anchor for lift install info

[tomsmith]

Hello all,

I purchased a 2008 Avalanche a few months ago and found my MaxJax was having problems lifting it due to the weight. The truck weight close to 6000lbs and the MaxJax lifting capacity is 6000lbs. That's just a little too close for comfort.

I'd leave the truck on 12ton stands (2 pairs) while I worked underneath, but that only gave me enough height to get it to the first set of safety stops.

I figured I need a higher capacity lift and I'm looking at a Dannmar Admiral 9000X. This is where it get's tricky.

I used the supplied wej-it anchors when I installed the maxjax but a few of the anchors were always troublesome. 2 on either side would never fully tighten without turning in the hole. I was able pull one of them out using a 3 ton jack and reinstalled it with quickrete anchor epoxy but I never fully trusted them.

I've been reading a TON of threads regarding lift installation and it seems that a threaded rod epoxied into the concrete is a much safer and better option than wej-it or friction anchors.

I'm thinking of getting 5/8 Grade 5 threaded rod:

with some Quickrete epoxy:

I suppose the power-sert anchors would be a good option:

But they still don't seem better than the rod + epoxy solution.

According to the quickrete site:

Maximum loads are calculated for a safe ty factor of 25% of ultimate load.
A 5/8” diameter threaded rod in a 3/4” diameter hole embedded to 5 5/8”
depth will yield an ultimate load of 28,000 lbs in 3,500 psi concrete at 4
hours at 77oF (25oC).

Source: http://www.quikrete.com/PDFs/DATA_SHEET-Anchoring%20Epoxy-%20High%20Strength%208620-31.pdf

When I had my maxjax, I never removed it. I understand some people do, but I imagine the majority just leave the columns installed. Even if you used threaded rod for Maxjax, you could still tilt it enough to clear the rod and wheel it out of the way.. I think.

So, thoughts from everyone on using threaded rod + epoxy instead of wej-it / power-sert?

The threaded rod is MUCH cheaper and easier - but I'm sure there's a reason why it's not the go-to solution and I'm hoping folks can provide opinions which may help others with their lift installs.

 

[BlackTalon]

Epoxy-set anchors usually have substantially higher pull-out strengths then wedge anchors for a given diameter. Hole prep/ cleaning is extra-important, as the bond of the epoxy to the concrete is what gives you the strength.

I'd skip the quikrete though and go to www.powers.com.

 

[readhead]

We use epoxy anchors very day and they work great. The rod should be minimum gr 5 depending on the application. Most of the all thread you buy at the home center is gr2.
The main thing is clean , clean and clean again. The hole should be a minimum of 1/8" oversize and brush cleaned and blown out with air. We also clean the rod with compatible thinner.

 

[sublimate]

Even if you used threaded rod for Maxjax, you could still tilt it enough to clear the rod and wheel it out of the way.. I think.

So, thoughts from everyone on using threaded rod + epoxy instead of wej-it / power-sert?

If you did move the lift, having rods sticking up to trip over/impale you would be a deal breaker for me. You could cover them with something, but it'll still get in the way - you lose all the advantage of the clear floor when you move the column.

Also, i think on some lifts having the rod sticking up might get in the way of the arms. Maybe you could cut them off pretty low so only the thickness of the nut & washer stuck up...?

 

[tomsmith]

Readhead, when you say, "We use epoxy anchors very day and they work great.", do you mean threaded rod or actual anchors like the power-sert in my original post?

It's a real pity Dannmar doesn't make a 9k or 10k version of the Maxjax. I really like the idea of the direct hydraulic cylinders doing all the lifting vs. a chain or steel cable setup.

 

[zkdiesel]

Readhead, when you say, "We use epoxy anchors very day and they work great.", do you mean threaded rod or actual anchors like the power-sert in my original post?

It's a real pity Dannmar doesn't make a 9k or 10k version of the Maxjax. I really like the idea of the direct hydraulic cylinders doing all the lifting vs. a chain or steel cable setup.

The chain/cables just provide equalization on most 2 post lifts..... Cylinders are connected directly to the arm collums

 

[sublimate]

It's a real pity Dannmar doesn't make a 9k or 10k version of the Maxjax. I really like the idea of the direct hydraulic cylinders doing all the lifting vs. a chain or steel cable setup.

http://www.mohawklifts.com/wp/consumer/automotive-lifts/2-post-lifts/system1/

 

[A**holes Garage]

We use Hilti epoxy anchoring systems.

 

[pattenp]

If you did move the lift, having rods sticking up to trip over/impale you would be a deal breaker for me. You could cover them with something, but it'll still get in the way - you lose all the advantage of the clear floor when you move the column.

Also, i think on some lifts having the rod sticking up might get in the way of the arms. Maybe you could cut them off pretty low so only the thickness of the nut & washer stuck up...?

He's talking about a standard floor plate 2 post lift. Those are not portable. They are normally fastened to the floor with anchors that stick up from the floor. The anchors are inserted after the lift is in place and driven down until the nut is to the face of the foot plate. The nut is tightened until the anchor sets. You may have a 1/2" or so of the threaded end sticking up beyond the nut but it does not interfere with the arms.

 

[wssix99]

According to the quickrete site:

Maximum loads are calculated for a safe ty factor of 25% of ultimate load.
A 5/8” diameter threaded rod in a 3/4” diameter hole embedded to 5 5/8”
depth will yield an ultimate load of 28,000 lbs in 3,500 psi concrete at 4
hours at 77oF (25oC).

This stuff is not safe to use. You'll see the disclaimer on the right side of the page: "• Not for overhead anchoring. Not for sustained long-term loads."

Epoxy is a funny thing and that it behaves differently for sustained and pull-out loads (like you'd see with a car up on a lift for a while) vs. short term loads and impacts. This stuff will creep on you, which you do not want: http://www.designnews.com/document.asp?doc_id=220176&dfpPParams=ind_183,aid_220176&dfpLayout=article

You can get industrial epoxies that will stand up to these loads. I recall that Hilti does make some - but you have to check the fine print in the data sheets to make sure they are rated appropriately. I'd look for "overhead" rated epoxy, which will probably fit the need.

 

[laser3kw]

The rod should be minimum gr 5 depending on the application. Most of the all thread you buy at the home center is gr2.

this ^^^^^^

 

[rockwithjason]

You have the wrong brand of stud anchor. Wegits are **** and have been since the 80s. They supply them because they are cheap. Get redhead brand ramset anchors and you your problems will be solved.

 

[A_Pmech]

If the lift is rated for 6k lbs, I don't see the issue. The lift isn't going to fail at 6001 lbs. Lifting equipment is usually designed to a minimum safety factor of 3:1.

 

[tomsmith]

If the lift is rated for 6k lbs, I don't see the issue. The lift isn't going to fail at 6001 lbs. Lifting equipment is usually designed to a minimum safety factor of 3:1.

Yep, I realize that it would have been designed to handle at least 7000lbs, but I just don't feel comfortable under it. Plus, I found the arms to be a little short - I can get the front arms on the recommended host point, but then then rears are maybe 6-8" away from the rear hoist point. On a normal car, not had any probs, but on a truck, the arms were a little short.

I'd hate to have it drop on me and all you guys shake your heads and say, "What was he thinking going above the manufacturers rated weight capacity??"

 

[RivennHewn]

Interesting changes coming to the construction industry regarding epoxy set anchors.

Where we have been required to have a special inspector verify our installs, the new code requires the installers to be certified.

No longer will contractors be able to install their own anchors without certification.

This is due to failures, and lack of skill/prep/execution of installs.

I believe this will apply to building plans under the 2012 code

http://www.concrete.org/Certificati...cation Program&cert=Adhesive Anchor Installer

 

[RivennHewn]

I guess I should say that this is due to the American Concrete Industry (ACI) needing another way to generate income, and lobbying whoever to require the certification that they are selling.

Rant over.

 

[JohnnieMo]

I also have an Avalanche and have stayed clear of the Maxjax for that reason. I'm curious how this works out for you.

For what it's worth I weighed my Avalanche 4x4. 6130lbs.


Sent from my Passport

 

[readhead]

RH, we have run into the inspection requirement recently. We are doing a three story building right now and have to schedule inspection for someone to watch us install the epoxy and the anchors. We have been installing our ledge angle for the decking with a couple of wedge anchors so we can keep moving and then spend a day installing anchors when the inspector is there. What a pita. Plus the owner has to pay for the special inspection.

 

[tomsmith]

I also have an Avalanche and have stayed clear of the Maxjax for that reason. I'm curious how this works out for you.

For what it's worth I weighed my Avalanche 4x4. 6130lbs.


Sent from my Passport

Yay, another Passport and Avalanche owner! I love my Passport

I couldn't find a Canadian retailer who sold the Dannmar Admiral 9000X so I reached out to Dannmar directly. They put me in contact with GES, who are pretty highly reviewed here, and they are lookig into shipping and customs options for me. I'm a little dissapointed because having it shipped from the US to Canada is going to cost me at least $1000 extra than if I could just buy it from here..

 

[JohnnieMo]

I'm looking at Liftking here in Calgary. The lifts aren't 'mobile' like the Maxjax but they are priced well. Might be jumping given the Canadian dollar though.

The passport is awesome. It's really well done.

Sent from my Passport

 

[David C]

If you are concerned about your wedge anchors, which is not only reasonable but prudent, you should do some research before proceeding.

Any chemical anchoring system used should have a current ESR report number. Read this report several times. Some above expressed concern about overhead loading which you should research. Note also that epoxy anchors lose capacity with temperature. And it doesn't take much increase in temperature to result in reduced capacity. A hot day with full sun on a concrete slab would be sufficient to markedly decrease load capacity. Hilti makes an acrylic chemical anchoring system as well as other concrete systems. You might research these too. I suggest you use a Hilti or Simpson product for any post installed concrete anchor. I do not suggest you use whatever is available in your local hardware store.

While you express concern with your wedge type anchoring system you may have failed to consider the capacity of the column base plate supplied with the lift Co. the grout below the BP, or the actual concrete strength, thickness, and reinforcing.

I would not, ever, get under one of these lifts installed on a 4" concrete slab on grade. I realize that if there were many failures that they would be reported and the industry would have to respond. However 4" is just too thin of a footing. Additionally you will find that for any of the ICC approved post installed concrete anchoring systems, 4" of concrete is not sufficient thickness and installation of anything but 1/4" and 3/8" diameter AB's is not allowed in 4" conc. slab on grade by most current building codes.

The statement that ACI generates income for requiring testing of anchor bolts is not really helpful. The certification of anchor bolt inspectors as well as the test proceedures is not done by the ACI though they do sell books. (I am not a member of the ACI or PCI either).

I have seen all types of anchor bolts fail under pull testing. It happens and this is why testing and inspection are required. Remember these anchor bolts are used in all types of applications, in schools, hospitals, as well as other buildings. The testing and inspection requirements are to protect the health and safety of the public, not to enrich the ACI.

 

[RossABQ]

Best post ever on the subject, David!

 

[readhead]

David brought up some excellent points. Our people have been trained and as I mentioned before cleaning everything before installation is a huge issue.

Check the expiration dates on the tubes also. I have seen tubes for sale that are three months expired.

Follow the manufactures instructions to the letter and be aware of temperature.

If installed correctly this stuff is magic. We are using fewer wedge anchors. We are seeing more and more where the concrete guys are not installing anchor bolts and the engineer has us installing epoxy anchors. After you have seen anchor bolts pulled out of the concrete I can see where this makes sense.

 

[RivennHewn]

The statement that ACI generates income for requiring testing of anchor bolts is not really helpful. ACI doesn't require testing. Engineers do. Special inspectors get paid to verify.


The certification of anchor bolt inspectors as well as the test proceedures is not done by the ACI though they do sell books. (I am not a member of the ACI or PCI either).

Please follow link: http://www.concrete.org/Certificati...cation Program&cert=Adhesive Anchor Installer

A common mis-practice of installing wedge anchors is just cranking them down tight, but not torquing them to proper spec.

Added note: Hilti does make a wedge anchor that meets spec at 2" embed depth.

 

[readhead]

RH, you are correct about wedge anchors. When we get into critical connections with wedge anchors we are required to torque to spec and then the special inspector checks them with his wrench.

People talk about how construction has become so expensive. They have no idea how much these special inspections cost, which adds to the overall cost of a project. We had to do one full pen weld on a project last week and because of where we are an inspector had to be flown in. The inspection fee for that one three hour weld was $2,600.

 

[RivennHewn]

Readhead,

I'm not sure how everybody else handles special inspections, but on our projects the client sets up a contract with the inspection company.

The client gets billed directly.

The cost does not go thru our company, or incur overhead charges.

I have done jobs were the fees for special inspections have topped $100K

 

[readhead]

All we do is line up the inspection with the owners rep or GC. We do the same thing as you do. We make sure everybody understands up front that we do not pay for inspection yet I will bring it up at the pre con meeting and everyone is surprised and no one has made any plans.

 

[tomsmith]

What kind of Hilti epoxy have people used in the past? I can't tell the difference between HIT-HY 200-A and HIT-HY 200-R.. I also don't know what the '500' does vs the '200'

I had a look though the Hilti site and it's pretty technical - most of the stuff probably makes sense to an engineer which I'm not..

I had a read through

https://www.hilti.ca/medias/sys_master/documents/hca/9125126012958/ASSET_DOC_LOC_3220858_APC_RAW.pdf

and saw that a 3/4 to 1 1/2 threaded rod would have a yield strength of 45k PSI. That seems plenty strong to me. That being said, the info is, like I said, way too technical for me.

Not that I'm an idiot but structural engineering is not my space. Want to know about C++ programming and Java development? I'm your guy. I get that reading tech spec documents is important, but that would akin to me asking a non-programmer to read through a programming guide to understand try-catch exceptions rather than just explain how it's an error handling mechanism to prevent a program from halting when something goes wrong.

My concrete is 12" thick, fibre and rebar reinforced. I believe it's 5400psi according to the concrete engineer that poured it.

 

[BlackTalon]

Best thing you can do is call Hilti. They have people to help you sort it out.

 

[wssix99]

I would not, ever, get under one of these lifts installed on a 4" concrete slab on grade. I realize that if there were many failures that they would be reported and the industry would have to respond. However 4" is just too thin of a footing.

If you don't want to get under one of these due to the fastening systems, that's fine but if you are worried about the strength of the concrete - you shouldn't be. The depth requirement is there for the fastener and bending capacity of the concrete. You are correct that you can't properly fasten these lifts to shallow concrete - but they do not need a "footing." (Creating a "footing" will often make for a weaker floor for certain types of lifts.)

If you think about how a concrete floor supports the weight of a parked car; the entire weight sits on the four tires' contact patches. The lifts have bottom plates that are larger than a car's tire contact patches, which spread the load out. It's entirely possible that the floor may see less peak loading from a car up on a lift than it does when the car is parked off the lift.

 

[David C]

Tom Smith,

The building code requirements for design of concrete anchor bolts got very complicated about 10 years ago. It is almost impossible to design AB's by hand calculation and for that reason Hilti and Simpson, (and probably others) provide proprietary computer programs to do the design.

A correct answer to your question is not simple and is beyond the scope of a post on this web site or the ability of most of the people who post here. This is in addition to any liability issues that would be assumed by anyone actually capable of answering your question appropriately.

From your post it appears that you are an expert in your field why not consult with an expert in this field. The design would probably take a few hours for someone experienced in the computer programs, something you could presumably afford. After all it is (only) your head, and what's that worth. You would need to provide him with lift design information and as-built information on your concrete pad footing, size, thickness, and location of steel reinforcing.

Installation of post installed anchor bolts is not trivial either. If it isn't done correctly they will not hold. Even if you pull test your anchor bolts, which is required by codes in most jurisdictions, a successful test does not in and of itself, prove that the installation was done correctly, or that you won't have a failure. The test helps, is commonly required and done, but it does not fully test the capacity of the anchoring system. The reasons are to complicated to go into here.

FYI, the fact that you have a 12" thick pad footing is great but the actual performance of the pad footing would depend upon it's size and reinforcing. Fibre does not do much for footing strength and you almost certainly don't have 5400 psi concrete.

Mr. WSIXX,

I don't undestand what you are saying. Sometimes people have a good point in mind but the written expression of it does not explain their thoughts. If what you are saying is that the capacity of the lift attachment system is dependent upon: lift column and base plate design, anchor bolt design, pad footing design, and preparation of the soil below the footing, I agree completely.

However a 4" structural slab on grade can not be designed to support the loads imposed by the lift such that: it would comply with current codes, or I would get under it.

I do not agree with your statement Creating a "footing" will often make for a weaker floor for certain types of lifts.). Maybe you have something in mind that is not well explained but I can't imagine what it might be.

In your statement: If you think about how a concrete floor supports the weight of a parked car; the entire weight sits on the four tires' contact patches. The lifts have bottom plates that are larger than a car's tire contact patches, which spread the load out. It's entirely possible that the floor may see less peak loading from a car up on a lift than it does when the car is parked off the lift. you neglected that eccentric loading is imposed by the lift arms on the lift column. This creates a moment in the lift column, column base plate, and concrete slab or footing. The concrete slab or footing, is not solely in compression as you suggest. If what you said were correct you would not need anchor bolts. This is for two post lifts, you are more correct for 4 posts lifts, especially if the post bases are not anchored to the concrete slab.

 

[wssix99]

Mr. WSIXX,

I don't undestand what you are saying. Sometimes people have a good point in mind but the written expression of it does not explain their thoughts

There is a common misconception that 2 post (or 4 post lifts) require a "footer" just to deal with the vertical loading. This is not the case for a typical slab on grade situation. The worry is that some folks stray away from a perfectly safe and strong situation by attempting to put in a lift "footer," which if done incorrectly, can introduce a unsafe and weak situation. (If moment resisting capacity is lost.)

If what you are saying is that the capacity of the lift attachment system is dependent upon: lift column and base plate design, anchor bolt design, pad footing design, and preparation of the soil below the footing, I agree completely.

My example is a simplified one, addressing only the vertical loading of the lift and compression strength of the concrete. This is what most people think of when they get confused that lifts need footers. (Getting in to more details on an NFL day could have eaten in to peoples' beer buzzes.)

There are moments imparted on the slab, but a 4" unreinforced slab is plenty strong to take that with a good margin of safety. (This is consistent with what manufacturers recommend for medium duty < 5 ton lifts.)

If the slab was elevated, reinforcing would be required. However a slab-on-grade takes advantage of the continuous support of the earth beneath it to resist the bending forces.

^ That being said - full disclosure - I did reinforce my garage slab for bending, but that was only because my fill underneath is of questionable quality and could develop voids beneath.

 

[Overhaulin63]

Sorry I moved my question to a more current thread.