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Re: Axial Tension in Masonry

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I'm looking at the COMMENTARY on ACI-530-88 (and I assume the newer version is the same), para
6.4:

"If axial tension develops in walls due to uplift of connected roofs or floors, the walls must
be reinforced to resist the tension."

Lew
===========================

Michael D Zaitz wrote:

> Think about this one,
>
> The masonry code ACI 530 does not allow masonry to resist axial tension.
>  Any strength in axial tension is neglected.  Now the problem.  TAke a
> 60 ft x 30 ft CMU wall structure with trusses spanning the 30 feet.  If
> you have a low pressure, say 15 psf for net uplift, that would give a
> force of 225 lbs per foot of wall.  Typically a bond beam is provided at
> the top of the wall for anchoring a plate to allow anchorage of the
> trusses and would weigh approxiamtely 60 lbs per foot.  Now we have 225 -
> 60 = 165 lbs of force remaining.  How would you resist this force
> considering axial tensile strength is neglected?  Typically in south
> georgia (not at the coast)  additional anchorage is not provided.
> Recently we have been adding vertical reinforcement in the wall taking it
> as far down as needed to get the required dead weight (of course
> contractors have complained.)  Any ideas?
>