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Re: Unreinforced foundation walls and PE/SE debate

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On 1 Feb 2005 at 9:46, Don wrote:

> Stan wrote:
> "Don't you use the soil pressure and calc. the masonry wall
> stresses? If you do, you find that reinforcement is required
> for any height of fill."
> Not necessarily.  Especially with a larger house, there is a
> significant dead load placing the wall in compression.  In areas of
> lesser wind loads, most of this dead load may always be there.  This
> compression plus the minimal tensile capacity of the mortar joints
> provide some bending capacity. So, even if an engineering analysis
> were performed, a wall of a given height and thickness, unreinforced,
> can withstand  a certain height of fill/lateral load.  I believe that
> this analysis, plus tons of empirical experience, resulted in the
> foundation wall tables of CABO, now IRC.
> PE/SE:
> I am a PE only (not "only a PE"), licensed in several east coast
> states.  I took the civil exam, and answered every structural-related
> question I could find.  It was the first year I heard of the SE exam
> being offered, but I wanted the flexibility of being able to proctice
> both civil and structural. Good thing, because I have done both.  I
> now (for the last 5 years) practice structural only, and am intrigued
> by the SE license/tests.  I do not think it would benefit my practice
> significantly, but may add weight in a conflict between two engineers,
> especially at the legal level.  So, finally to my question:
> Could someone please expalin to me what the three tests are, how long
> they are, how difficult they are, and what SE states require which
> tests?  Could you please reply directly to dbryant61(--nospam--at) as I am
> in digest mode.
> Thanks,
> Don

Don et al,

What Stan wrote is true, i.e., calculations indicate that most 
basement walls do not withstand lateral soil pressures without 
vertical reinforcing.  What Don says is also true ? in Ontario, the 
prescriptive part of the code for houses and small buildings allows 
up to 8'-0" basement walls without reinforcing, provided that the 
soil height does not exceed 7'-7", for an 8" concrete wall, or 6'-0" 
for a 10" block wall.

Many thousands of homes have been built with unreinforced concreted 
and masonry basement walls.  However, my experience has been that 
some of the masonry block walls do not stand up under certain 
conditions, e.g., poor soil, water pressure, vehicle loading.  
Consequently, I never approve masonry walls for basements.  Besides, 
they trap water in unfilled cells and leak.  

I am also careful about long walls and gable end walls in concrete 
with little vertical load.


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