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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

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


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?