Anchor Reinforcement
Anchor Reinforcement
(OP)
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. I posted this question in the ACI (code) issues section but am posting here as well. Thanks!






RE: Anchor Reinforcement
I don't see how the anchorage reinforcement (or the anchorage for that matter) could be anyone's responsibility but the guy doing the foundation. (Especially if it is post-installed.) In fact, I'm not sure if I've ever left the anchorage design (with or without reinforcement) to a vendor/contractor.
RE: Anchor Reinforcement
RE: Anchor Reinforcement
The equipment manufacture is responsible for their attachment to the base structure if thru the course of their calculations they find they need anchor reinforcement by nature of the name they should be designing it, if their anchor reinforcement design needs to rely on development with the in place bars then that should be clearly noted in the shop drawings and reviewed by the base building design engineer. They should really be providing the connection loads as well for base building engineer to review the adequacy of the structure as more often than not we're working off of a stock spec sheet from very early in the design life of the building.
RE: Anchor Reinforcement
RE: Anchor Reinforcement
Been in your situation before and more often then not the person on the manufacturers end didn't know how to design anchorage reinforcement and was simply putting numbers into Hilti Profis and it not working unless he/she checked the "reinforcement" box in the program. Took a week of back and forth with for them to admit that. Usually ends with us up-sizing the pad by a couple inches to get an edge distance to work because the unit size wasn't really going to change.
RE: Anchor Reinforcement
RE: Anchor Reinforcement
RE: Anchor Reinforcement
I'm from a different world. In the design I do, we design everything based on the certified equipment drawings (from a vendor that has been selected). In fact, we use to do it based on as-builts....but those days are long gone.
I'm not sure I understand how your process is working anyway......how do you provide reinforcement for a already poured foundation? It sounds to me like this is a post-installed anchor situation. I can see providing reinforcement all over the place in a worst case design approach you are describing.....but that would be highly wasteful in most foundation designs.
RE: Anchor Reinforcement
Sometimes they come back and hire us to do the design.
Regardless, I've never needed, or have been asked for anchor reinforcement. Having never fielded that question, I would probably just tell them to provide an anchor that doesn't need it or tell me what they need and I'll draw it with some sort of CYA note about "design by others".
RE: Anchor Reinforcement
If anchor bolts are furnished by the general contractor or the owner, we specify bolt size, extension, loads, and everything below the face of the concrete is designed by others.
My bigger concern with stuff like this is not so much arguing about who designs it, but failing to have that discussion and both parties assume the other party did it.
RE: Anchor Reinforcement
Usually the Contractor hires a 3rd party engineer to provide the design but I agree, it's likely they don't know how to provide the design and start pushing back.
Typically these are for new construction only where the foundation hasn't been poured yet so reinforcement can be added and/or the foundation modified.
Right now I'm to the point where I will provide the design just to avoid any further delays (and potential claims from the Contractor). I'll likely need to word my response in a way that clarifies I'm doing this at the request of the Anchor designer so the Contractor can't come back with a change order.