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Re: Strength Design of Masonry Wall (per UBC)

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The T.21-J compliance requirement appears to apply only to the in-plane seismically loaded piers.  By your email, this is not your case, so the strength-level capacity of the wall is 4,137lbs, while the allowable capacity is about 2,944 lbs (I don't know the M/Vd ratio).  Looks right to me.
V. Steve Gordin, SE
Irvine CA
----- Original Message -----
From: Bill Allen
Sent: Monday, July 02, 2007 14:19
Subject: Strength Design of Masonry Wall (per UBC)

I would like a confirmation that I’m looking at out of plane shear strength correctly.


Wall thickness = 8 in. (nominal)

Solid Grouted

F’m = 1,500 psi

b=12 in.

d=5.25 in.

Ae=91.2 in2 (from the equivalent solid thickness)

#6 bars at 8”

Temp. & Shrinkage horizontal steel


Mu/Vud >1, Cd=1.2, Vm(max)=63CdAe=63(1.2)(91.2)=6,895 lbs.

Vm=CdAe√F’m)=(1.2)(91.2)√(1,500)=4,239 lbs. < 6,895 lbs.

Vs = 0 since ρn = 0 (no shear reinforcement)

Vn = 4,239 lbs.

φv = 0.6

φv Vn = (0.6)(4,239) = 2,543 lbs.


Is this right?


If so, shear is limiting my design using strength design and it didn’t come anywhere close using working stress design.




T. William (Bill) Allen, S.E.


Consulting Structural Engineers
V (949) 248-8588 F(949) 209-2509