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Re: Basement Wall Cracking[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Basement Wall Cracking
- From: Jim Kestner <jkestner(--nospam--at)somervilleinc.com>
- Date: Thu, 24 Dec 1998 07:39:16 -0600
The position, pattern and width of the cracks make me believe the cracks
are structural in nature. Your comment about the pattern being "like the
tributary area load
Are there drawings of the original construction? The wall height seems low, which makes me think that this is a home and not a commercial structure. If it is a home, it is standard practice (in this part of the country) to use plain concrete (unreinforced) to span that distance. How do the stresses check out for the unreinforced section? Are there unusual loadings at that point on the outside of the structure? What type of material did they backfill with? Is the drainage adequate?
Your idea of the rebar (if any) being misplaced is a reasonable one. Over the years, I have discovered that there may be so many possibilities for the reason why something cracked that it is difficult to speculate on exactly what the cause may have been. About the only thing you can do is suggest several possibilities unless you carry the investigation far enough to actually find out.
Jim Kestner, P.E.
We have a basement wall in a building that has been in service since 1977. The problem is that it has cracked along a 55 ft section close to one corner. Wall clear height 8'-0"Wall thickness 8"Main 2.5mm crack at 5' above floor slab.Length of main crack about 14'Crack width maximum 2.5mm Bifurcating cracks run off at about 30 degrees to contact floor and ceiling slab respectively about 20' away. Crack width decreases from the 2.5mm to 0 over about 20' each end of main crack. There are other secondary cracks but the main pattern is so much like the tributary area load distribution for a two-way slab. ____________________________________________ \ / \ 1mm /0.5mm \ / \ / \ 2.5mm / 1mm \-------------------/- - - - - - - - - - - - - - -- - - - - - - / \ \ / 1mm \ \ / \ \ / \ \ / \ \________________________________\________ The scales are grossly out of proportion but the pattern is as shown. 5'-0" dimension on bottom half. My numbers suggest that if the wall rebar was in the centre of the wall instead of at the inside face then I can expect about 1.5mm crack width? This, from elementary geometry means an out of plane deformation of about 7mm, which is not much different from tolerances for waviness etc in concrete. Would appreciate any comments or ideas on what could be causing this in an otherwise sound wall for the remaining perimeter.
- Basement Wall Cracking
- From: vicpeng
- Basement Wall Cracking
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