Adding Equipment to an Existing Building

[Brooklyn2012]

I have a building that was designed 30+ years ago for two reactors. Only one was installed. The owner wants to install the second reactor. Does the building need to be seismically evaluated for the current building code?

IBC Section 102.6.1
A building or portion of a building that has not been previously occupied or used for its intended purpose in accordance with the laws in existence at the time of its completion shall comply with the provisions of this code or the IRC, as applicable, for new construction or with any current permit for such occupancy.

Has anyone encountered this situation before?
Is this clause relevant to this topic?

How did your project handle the situation?

 

[WARose]

I've dealt with this sort of thing before. If the new reactor is identical to the design reactor....you are probably ok.

I think there is a clause in the IBC that if you are not changing the design gravity or lateral load by 5 to 10%....no alteration is necessary. You could probably make your case with that.

In my case, I contacted the local code official for his buy in.....and he agreed. You may want to do the same. Although let me warn you: if he/she goes against you....everybody will be griping that you contacted them in the first place. So be ready for that.

 

[milkshakelake]

According to ASCE 7-10, the answer is most likely yes, the building will need to be seismically evaluated to new code. Unless the reactor is isolated from the rest of the building. I'm not sure about IBC provisions, but the ASCE one is used where I practice.

11B.3 STRUCTURALLY DEPENDENT ADDITIONS

Where an addition is not structurally independent from an existing structure, the addition and alterations to the existing structure shall be designed and constructed such that the entire structure conforms to the seismic force-resistance requirements for new structures.
EXCEPTIONS: The entire structure shall not be required to comply with the seismic force-resistance requirements for new structures where all of the following conditions are met:
1. The addition complies with the requirements for new structures.
2. The addition does not increase the seismic forces in any structural element of the existing structure by more than 10 percent unless the capacity of the element subject to the increased forces is still in compliance with this standard.
3. The addition does not decrease the seismic resistance of any structural element of the existing structure unless the reduced resistance is equal to or greater than that required for new structures.

 

[gte447f]

milkshake, that clause from ASCE 7 seems to be applicable to building additions. I don't think that is the case for the OP. The OP's case may still have to conform to current code (not sure), but I don't the section of ASCE 7 that you cited is applicable.

 

[phamENG]

From my response in the Seismology forum (which you should red flag yourself and have deleted to prevent having multiple threads going):

I haven't dealt with it, but it certainly sounds like it applies directly to your situation.

It makes sense. The reason we can keep using things that have been around for a while that 'don't meet code' is because they've proven themselves already. Structurally speaking, the building code is concerned first and foremost with reliability. Can we rely on these materials to do a job if they are arranged in this way? Because we're installing new, untested materials, we take certain measure to ensure they will work through testing and inspections and safety factors. Well...if a building has been doing a job for 50 years, we don't have to be as rigorous in our statistics. We already know that this material is above a certain threshold regarding strength, so it changes the calculation a little. The IBC/IEBC doesn't do a great job of dealing with this directly, but accomplishes it circuitously.

Now, if the building was never used for the purpose...we don't have that history of knowing that it can do it. Sure, the building hasn't collapsed, so that's something, but it hasn't not collapsed while also loaded with the second reactor. Since we don't know, we fall back on the 'new construction' reliability requirements. To meet that, we have to treat it as if it were a new building.

 

[milkshakelake]

I guess some more context is needed from OP. I used to design chemical plants that had heavy equipment everywhere. Sometimes we'd just add the equipment and not worry too much about overall seismic of the structure because of the 5% rule (I think it was 5% where I worked, might've been a company standard, though ASCE says 10%). But if it's a small building or mat foundation with just one or two pieces of equipment on it, we'd consider it a significant change and design the whole thing for seismic.

Since the building was already designed for a reactor, but under old codes, I'd think that a re-evaluation is needed. A reactor would be a significantly heavy piece of equipment, unless the building is full of heavy equipment everywhere.

 

[Brooklyn2012]

Thank you all for your responses. I agree with all of the comments regarding additions.

In this case, the building was designed for 2 reactors. Only one was installed. Now we want to install the second one. So, it is not an addition.

We are not increasing the seismic demand beyond that as originally designed.

 

[phamENG]

Right, but if the old design is no longer deemed sufficient or reliable - whether it's because seismic loading has increased or our understanding of the system used has improved - you can't use it.

 

[Brooklyn2012]

But if the equipment had been installed in 1995, we would not be having this discussion. And it would be fine.

I have submitted a formal request for interpretation to ICC.

I will post the response when I receive it.

Thanks again for your participation.