Do Block Walls Count for Lateral Sway Bracing?

10/24/2022

I have a 2 story hotel that is being converted to 13R apartments. The structure has filled block walls, and concrete slab ceilings on both floors.

My question is about the seismic bracing.

I have cored 5-inch holes for the 3-inch main that is to run the length of the building, through the block walls. The block walls are 12'-0 apart.

Can the block walls be counted as lateral sway bracing?

Or, do I need to place braces as usual, based on pipe weight?

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9 Comments

David Kendrick

10/24/2022 08:32:40 am

Is seismic bracing required in 13R?

There is a reference to hanging and bracing per NFPA 13 and to me that seems vague. Or its Absolute.

We brace sprinkler arm overs when system pressure is above 100 psi and penetrating a ceiling.

Does the bracing reference include seismic?

10/24/2022 08:33:03 am

Unless your all thread rod is 6 inches or less, I don't see where you could omit seismic bracing. I would account for it if I had this scenario, and expect the AHJ to look for it. I'm not a seismic expert though.

Todd E Wyatt

10/24/2022 08:38:51 am

Hotels are classified as Group R-1 (Residential) Occupancy Classifications (OC). Apartments are classified as Group R-2 (Residential) Occupancy Classifications (OC).

Group R occupancies are permitted to use NFPA 13R IF it meets ALL of the following conditions per 2021 IBC 903.3.1.2 :

1. Four stories or fewer above grade plane.
2. The floor level of the highest story is 30 feet (9144 mm) or less above the lowest level of fire department vehicle access.
3. The floor level of the lowest story is 30 feet (9144 mm) or less below the lowest level of fire department vehicle access.

If this "Change of Occupancy" project meets these 3 conditions, 13R may be used.

koray uluc

10/24/2022 09:09:22 am

i don't think that such installation can be used as siesmic bracing, The block holes do not fix pipe tight because of required clearance between pipe and solid wall (minimum 2" bigger, for pipes under 4" diameter) to avoid pipe brakage during siesmic movements.
in absance of siesmic bracing the pipe can move inside this large hole and break during an earthquake.

Colin Lusher link

10/24/2022 09:16:26 am

Yes, Seismic/Sway Bracing is indeed required for NFPA 13R for those who asked the question above. Pipe hangers and bracing shall be per NFPA 13, which clearly requires sway bracing.

And NO, the penetrations through the CMU wall do NOT count as sway bracing. The only condition where this would count as bracing is where a vertical standpipe penetrates stairwell floors in a multi story building; in that condition only is the penetration allowed to act as a lateral pipe support.

Randy Rathert

10/25/2022 09:00:42 am

I love the banter and reference to ( code) but it is a especially helpfull when the answers are backed by the actual section of code.
If that doesnt happen , then its just opinion.

Colin Lusher

10/25/2022 11:32:22 am

Thanks for your opinion Randy. First, NFPA 13 and 13R are 'standards', not 'codes'. And second, when I provide a response to a question here, I'm looking to point the questioner in the right direction, not to do their homework for them. And third, if you're not bringing anything to the discussion, why bother with a snarky response?

Alex

10/24/2022 10:18:25 am

Hi,

Like others have mentioned, I do not believe the CMU wall counts as sway bracing.

Thanks,
Alex

Ryan Hinson

10/25/2022 11:51:48 am

First off, is seismic protection required per the applicable building code or ASCE/SEI 7?

If it is, is the block wall considered a building structural component or not? Is all- or part of your piping anticipated to move with the concrete/block walls in the event of a seismic incident per NFPA 13 (2022) Section 18.5.13?

Per NFPA 13 Section 18.5.1.2, "the structural components to which bracing is attached shall be determined to be capable of resisting the added applied seismic loads." This direction should be coming from the cognizant structural engineer on the project...if there is one. If not, one should be consulted.

I'm inclined to say that these walls MAY be used as structural components to which bracing members can attach for lateral bracing where your main is penetrating through them (as appears indicated in the original post)...IF they are made tight by other means to make them 'tight' per Section 18.5.11.2. There still needs to be bracing assemblies used to eliminate this rattling potential of the pipe within the nominally 2" larger cored holes as indicated. Other facets of seismic protection such as placement of flexible couplings relative to bracing locations are addressed in NFPA 13 Section 18.5.

It should be noted that, "where required, the clearance shall be filled with a flexible material that is compatible with the piping material" per Section 18.4.8 and "no clearance shall be required where piping is supported by holes through structural members as permitted by 17.1.7.3" per Section 18.4.10. Section 17.1.7.3 permits holes through solid structural members to be hangers supporting system piping.

Though your walls may be sufficient for lateral bracing and vertical pipe support, they may be insufficient to withstand a longitudinal forces acting to tip the wall over. Again, a structural engineer should be looking at this.

Good luck!

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Do Block Walls Count for Lateral Sway Bracing?

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