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RE: Seismic Loading on basement walls

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Currently there are no building code requirements regarding seismic soil forces on walls.  That does not mean it does not exist.  There is commentary contained in NEHRP Resource Paper #12 found at:
This has been a topic kicked around at the BSSC for quite some time.  We can't agree to a building code requirement.  But just because we can't resolve this into a building code does not mean that there is good data to characterize the problem. 

Regards, Harold Sprague


From: vicpeng(--nospam--at)
To: seaint(--nospam--at)
Subject: RE: Seismic Loading on basement walls
Date: Tue, 21 Sep 2010 06:09:57 -0700

Hi Gary.


Current code with seismic climatic data implies that seismic must be addressed for all “engineered” structures and elements, however, as far as I am aware Part 9 does not yet have that requirement.  That said, a 9’ wall becomes an engineered component and seismic must now be addressed.  Seems to me that it won’t be a significant issue in your jurisdiction.  Care must be taken in which EQ model to use.  For certain walls, Monookabe is very conservative and should be used with discretion.  OTOH there is discussion at present here in BC on the loads being developed on parkade walls by the 2006 code requirements and there is, as yet, no agreed resolution …


I’ll check and see if there is any progres with the committee working on it.


Thor A. Tandy P.Eng, C.Eng, Struct.Eng, MIStructE, MSCSE
Victoria, BC




From: Gary L. Hodgson and Assoc. [mailto:design(--nospam--at)]
Sent: Tuesday, September 21, 2010 4:49 AM
To: seaint(--nospam--at)
Subject: Re: Seismic Loading on basement walls


Fellow Listers,
I am hoping that some one who lives in shakey country can help. All of a sudden seismic design of residential basements walls has arisen here in not so shakey Ontario.  A fellow engineer called me as he had his sealing of drawings of a residence with 9 ft high basement walls questioned by a member of the BMEC (Ontario quasi government body, the Building Materials Evaluation Commission).  Beats me why such a person would even be involved because usually the local municipal building department only reviews such drawings.  The Ontario Building Code has a section on "housing and small buildings", i.e. under 600 sq m and 3 stories or less ( a presciptive section) which allows plain concrete basement walls up to 8 ft high. As soon as the wall is more than 8 ft high, it has to be approved by an engineer. Hence this problem arose.  He did call for reinforcing, but he wasvquestioned on seismic loading. I am hoping some of the helpful members can point me in the right direction to publications on this or give some advice.

On 9/14/2010 5:51 PM, Joseph R. Grill wrote:

From my previous post I will say that all the licensing issues appear to have been worked out.


The steel stack that I am working on is not tall being less than 50 ft.  There are some breech openings in the stack near the base.  The openings are round and will be “stiffened” due to horizontal pipes the same diameter of the opening that will be welded to that location.  I have to go to my “archives” located in my not so clean garage to locate a reference that I only think is there.  I had to reduce the archived library some time back.  Anyway, it has been quite some time since I have done a stack design and I am looking for a reference/example of reinforcing breech openings.  I have some pages from ASME with some stack design requirements, but it doesn’t (at least the portion that I have) say a lot about the breech reinforcement.


I will say that in doing some very quick ballpark calcs, I’m not sure the reinforcement is all that critical in my case.  If I take the portion of the stack between the breech openings (without stiffeners) and check compression stresses from gravity and wind. The stresses appear to be o.k.  that would even be with assuming the width of the compression element does not increase due to the circular nature of the opening and being unstiffened.  Anyway, if anyone has some a reference, example or help in general, I would certainly appreciate it.



Joseph R. Grill, PE

Verde Valley Engineering, PLLC

email: VVEng(--nospam--at)


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