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Re: URM Building per UCBC

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It is not uncommon to shotcrete interior or exterior faces of URM walls under similar circumstances, however this typically will
involve some foundation strengthening.

Steven A.
Los Angeles


lrhauer(--nospam--at)earthlink.net wrote:

> I am engineering a seismic retrofit to a one story URM building in seismic zone 4, using the special procedure of the current UCBC, Appendix Chapter 1 and I am stumped on a couple of things someone out there might be able to help me with.
>
> First, the 2 exterior 13" thick URM walls have an adhered veneer of about a 1" thick portland cement backing applied to the face of the 13" URM, and then about a 3/4" veneer applied with a mortar bed, in other words, no veneer ties. since it is an adhered veneer without ties, it would seem to me Section A113.t of the UCBC does not apply. Am I correct??
>
> Second, I have one interior 13" URM property line wall which had very low mortar tests with an average Vto of about 15 psi. I can drop these from my other tests since they are the lowest 20%, but I am concerned over Section A106.3.3.4, item #2 requiring "Individual unreinf. masonry walls with Vto consistently less than 30 psi shall be entirely pointed or removed". Repointing doesn't seem to make sense since it will only effect the outer 3/4" of masonry and I think the mortar strength is low throughout the thickness of the wall since it is an interior wall. Removing the wall is uneconomical. If I meet the h/t requirements of 16, provide wall anchors at the top to the roof, and introduce a lateral resistive element such as a plywood shear wall directly in front of and parallel with the wall, can I do away with the pointing/removal requirement, or is the logic such that the wall is a hazard in its present condition?
>
> Any enlightenment would be appreciated.
>
> Larry Hauer S.E.
>
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