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Anchor Reinforcement

Anchor Reinforcement

Anchor Reinforcement

Generally when I do a structural design with MEP equipment, I require the Contractor to design the anchorage and provide the calculations for review. I usually have a note that stipulates the equipment pad sizes need to be coordinated with the anchorage calcs regarding thickness and edge distance requirements. Most of the time there's no problem with this approach however a few times the anchorage calcs show that anchor reinforcement is needed (either for tension or shear). My position is that the reinforcement is needed by the anchors and not because the concrete foundation/equipment pad is inadequate structurally. Therefore, it should be designed by the Engineer providing the anchorage calculations. However, I've gotten into countless arguments with Contractors and their Engineers who feel the reinforcement should be designed by the Engineer doing the foundation/equipment pad design. Does anyone have any thoughts on this or can shed light on what they consider is the responsibility of the anchorage designer vs the foundation designer? If I know that reinforcement will likely be required I make that note in the drawings but most of the problems come from smaller equipment that I didn't expect anchor reinforcement to be needed. Thanks!

RE: Anchor Reinforcement

First of all, you're pretty lucky that the suppliers are taking on the anchorage design. I would say that if they're assuming supplementary reinforcing, they should add it. But I have a feeling that the anchorage supplier thinks that she/he's creating a conflict with the building designer plus they just don't want to do it.
But if you're seeing the design in the submittal phase, you've got the hammer. You can:
  1. Reject the submittal based on the lack of the supplementary reinforcing.
  2. Tell the contractor that they can either have the supplier add the reinforcing or they can use an alternate means to increase the anchor capacity.
Personally, I would thank my lucky stars that the supplier's designer is taking this on and add the reinforcing. We have a devil of a time getting them to do this. Sometimes you can be right, but the job is still getting delayed.

RE: Anchor Reinforcement

For me this is probably one of those 'choosing your battles' situations. I'd agree that it's their anchorage that needs it and in theory they should design it.

That said, when I'm in similar situations I usually make a half-hearted attempt to get the other engineer to design the rebar and then end up doing it myself. I already didn't have to run through the worst of the anchorage calcs and sizing a couple bars doesn't take much effort. Probably takes more of my time to argue with the contractor and other engineer than to just do it.

See this kind of similar to anchor bolts for pre-engineered buildings or other structures. Generally those guys will design the anchor bolts for the steel failure mode and leave the concrete failure modes up to the EOR. They see it as part of the foundation design. I see it as part of their anchorage design. I lose every time.

RE: Anchor Reinforcement

@JedClampett - I will say that most of the time the Contractor will either have their own in-house engineer provided the anchorage design or they will hire an outside engineering firm to do the design. Rarely do I see the supplier provide the anchorage calcs although it is not uncommon. I agree it's always a fight over who's responsible and it causes unnecessary delays.

@MrHershey - I agree, I think I'm at the point to where I'll provide the design and rebar to keep the project moving. I just don't want the Contractor to come back with a change order. I'll have to figure out a way to word the response to make it clear we're doing this at the request of the anchor designer.

RE: Anchor Reinforcement

Change order is sometimes an argument. Assuming that the added bar isn't outrageous and obviously would have been needed, I'd stick to the argument that they could have made their anchorage work with a couple extra bolts or a few extra inches of embedment and chose not to. That's a cost-savings effort on their part. Which is totally fine, I'm all for saving money. But if they want to double down and put in a change order for the bar that was added due to their cost savings then they're getting back-charged for the engineering effort.

We typically see contractors do their own anchorage as well. Not in-house usually, but will farm out to someone. Occasionally we'll do that kind of work for contractors. Not the sexiest or most interesting work, but usually fairly headache-free and can do decent financially.

RE: Anchor Reinforcement

In my neck of the woods, the suppliers won't do the calculations and the contractors aren't smart enough to price having the task done by others.

Quote (Mr. Hershey)

See this kind of similar to anchor bolts for pre-engineered buildings or other structures. Generally those guys will design the anchor bolts for the steel failure mode and leave the concrete failure modes up to the EOR. They see it as part of the foundation design. I see it as part of their anchorage design. I lose every time.
My all time pet peeve. The building suppliers know they can wait you out. The GC has their building and all that's keeping them from putting it up is that pain in the backside EOR.

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