Equipment Suppliers vs. ACI 318 Appendix D 1

[JedClampett]

Another week, another battle with equipment suppliers on providing anchorage calculations for their equipment. Why is it that they are so resistant to doing the final step in their design? We've beefed up our specifications, requiring that the supplier provide the anchorage calculations, and yet, they still resist.
Their excuses are:
* We don't do concrete.
* We don't know what your concrete structure is good for.
* No one asks us to do that.
* Lalalalalala la.
* We're just not doing it.
My point is that if the equipment supplier doesn't do that calculation, their incentive is to reduce the number of anchors, decrease the spacing or reduce the edge distance until they can't be designed. I'm not trying to get out of work, but if they're going to do the seismic and/or wind analysis, they should be responsible for the anchorage.
Is anyone else aggravated by this or even have this problem? Any equipment supplier engineers out there?

 

[slickdeals]

Charge the contractor or the owner a additional service "fee" for it and design. Less aggravation, a little more money and comfort that it has been done right. You will probably spend more time reviewing/arguing/sending emails on this silly topic than it's really worth. That time already has paid for your design and probably the cost of putting those anchors in

But if you want to stick to your specs, go for it. I don't think it is too different from a Tower Crane supplier who will design "everything" except the foundations, even if all the Geotech parameters are spelled out.

 

[abusementpark]

What type of equipment are you requiring this for?

 

[JedClampett]

slickdeals, that seems reasonable. But one issue is that our clients negotiate to the bare bones in our construction services contracts. Spending time going back and forth on anchor design is a luxury. Plus there's the issue that unless the supplier is involved in the entire design, they might leave me with an anchor that can't be made to work (load too high for the edge distance, etc.).
So let's say I do my design and the tell the contractor they need to embed 8 one inch diameter stainless steel anchors 12 inches in Hilti RE-500 SD epoxy (pretty ridiculous). They come back with an extra saying their supplier told them that six 3/8 inch anchors embedded 3 inches would work. It's nice to have that fight on the contractor side of the fence.
abusementpark, most of our problems are with FRP tanks. But I ran into an issue last week with lime silos.

 

[JStephen]

Typically, if we're checking concrete anchorage, we're also designing the whole foundation, and that involves adjusting dimensions and reinforcement as required to make the anchorage work. The two problems are not independent, and doing either part without consideration of the other has some potential problems.

If the equipment supplier normally furnishes, say, fiberglass tanks, they may in fact have zero knowledge of concrete design (for example, you may have a mechanical engineer handling the tank design who doesn't normally deal with concrete). If you are already a structural engineer, and the effect of your requirement is to make them go hire some other structural engineer to complete the foundation design that you've started, that's not necessarily an efficient arrangement.

 

[amec2004]

I have done lots of equipment foundation design, ranging from pumps, horizontal vessel, vertical vessel, stack, boiler, tank, turbine and vibrating machinery etc etc.

None of the equipment vendor did the anchor bolt design on *concrete part*. The vendor just did the anchor rod material part check. It's not realistic and not reliable to ask the vendor to do the anchor bolt concrete part design. It's simply because they are Mechanical engineer, not Structural engineer.

The *concrete part* capacity normally governs the anchor bolt design capacity.

anchor bolt design crane beam design

http://www.civilbay.com

 

[Gumpmaster]

Jed, I have the same problem as well. I think the best way to overcome this is to have a preconstruction meeting with the general contractor and provide them what you expect and will approve with regards to equipment anchorage submittals. The general needs to be aware of your expectations so they can beat their subs over the head.

On several of the projects that I've worked on, the contractor goes out and hires an outside engineer to perform the calculations. There are small engineering shops that somewhat specialize in this type of work.

Like you said, you have to have an ironclad spec and stick to it like glue. The first couple of submittals may be painful, but after that it gets easier.

 

[JedClampett]

JStephan, I can guarantee 100% of the time that once the load gets into my foundation, it can take it. The moments and shears are large with respect to anchorage, but small in comparison to our minimum foundation designs.
amec2004, I guess it's time to crack open that ACI 318 and learn about concrete anchorage. Or hire a structural engineer to do these calculations. If you locate the lugs, size the anchors and specify the number, you've restricted my options in a way that I can't provide any meaningful input. If the anchorage won't (or can't) work, what are my choices? The concrete is usually poured by then, so I can't increase the size of the foundation for increasing edge distances. My issue is that unless the aspects of anchorage design are appreciated by the equipment supplier, I end up the bad guy.

 

[JStephen]

JC, just for reference, in our work, the most common issue along these lines isn't the anchorage strength of the bolts, but rather the bolt forces themselves, usually the forces associated with internal pressure, tank failure or frangibility requirements, rather than wind or seismic loading.

For industrial work, the foundations and anchorage in the foundation are usually designed by others. We'll specify size and layout of bolts and loads associated with them. I don't recall any issues with this approach, other than the overall bolt force being higher than expected on occasion. Our work generally involves cast-in-place bolts, and that may simplify the situation.

 

[wannabeSE]

Jed,

Perhaps you can add a table of anchor capacities in the specifications. The table could include typical anchor sizes, embedment, minimum spacing and edge distance (for full capacity), and conservative tension and shear capacities for design. Also, have the specifications give the equipment supplier an option to calculate the capacity per ACI 318.

 

[dhengr]

Jed:
As much as we all dislike the convoluted and overly complicated ACI318, app. D, there probably isn’t anyone better able than the EOR to design and check the anchor bolts. Sad, but true. Spec. cast in place anchor bolts ONLY, and remind the G.C. and their equipment suppliers that foundation conc. usually gets placed fairly early in the bldg. process. So you need their footprint, A.B. size and grade, location dimensions, all loads induced by the equip. or on it, vert., lateral, wind and E.Q., any vib. considerations, etc. before found. design and Struct. drawings going out for permitting. They probably can’t design the A.B’s. to keep you out of potential trouble, so you better do it. But, if they want to sell the equipment they have an obligation to provide the needed design info. in a timely manner. This is the age old communication problem btwn. disciplines or trades. Their equip. doesn’t get installed for a year after the A.B’s. are placed. So, why do you have to know anything about their equip. until a week before it gets installed. Or, don’t bug us with the details now, our plumbers will cut through that there beam when they install the piping, so don’t worry bout it.

 

[amec2004]

OK, here is my replies to multiple posts above

>> amec2004, I guess it's time to crack open that ACI 318 and learn about concrete anchorage. Or hire a structural engineer >> to do these calculations.

You have to tell them your foundation geometric size and how it is reinforced for anchor bolt Anchor Reinforcement. That normally won't be available during early stage of project. For the time you are are arguing with the vendor or exaplaining to their hired PE you already get the calc done by yourself.

>>but rather the bolt forces themselves, usually the forces associated with internal pressure, tank failure or >>frangibility requirements, rather than wind or seismic loading.

For tank it shall be wind or seismic governing.
For pump it may be nozzle load governing, espcially when there is trasient or thrust load

>> For industrial work, the foundations and anchorage in the foundation are usually designed by others.

Yes. It's by Structural engineer.


>>Perhaps you can add a table of anchor capacities in the specifications. The table could include typical anchor sizes, >>embedment, minimum spacing and edge distance (for full capacity), and conservative tension and shear capacities for
>> design. .

That's not practical as it may end up with the very little ancgor bolt capacity and not useful.

In anchor bolt design, the combinations of different edge distance of all 4 edges, embedment, anchor reinforcement, concurrent imposed tensile and shear forces etc is unlimited. It's impossible to make such a look-up table.

>> Also, have the specifications give the equipment supplier an option to calculate the capacity per ACI 318

Eqipment suppliers just do the anchor rod material part cpacity check and know nothing on the concrete part. That's what their software can do and they don't know concrete.

anchor bolt design crane beam design

http://www.civilbay.com