RE: Unblocked Plywood Diaphragm Deflection Calculation

• To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
• Subject: RE: Unblocked Plywood Diaphragm Deflection Calculation
• From: "Jeffery Seegert (x 485)" <jbseegert(--nospam--at)matrixti.com>
• Date: Wed, 19 May 1999 13:42:29 -0400
```Deflection ={(5vL^3)/(8Eab)}+{(vL)/(4Gt)}+ (.188Le)+{[(sum(DX)]/(2b)}

v = shear in the diaphram (plf)
L = total width of diaphram (ft)
E = 1.7 e 6 Douglas fir-Larch No 1 2x8's  (psi) see Table 23-I-A-1 of
1994 UBC Volume 3
A = area of top plate (in)
b = diaphram depth (ft)
G = 90,000 (psi) (for Exterior C-D or C-C Grade Panels) see table 23-2-J
of 1994 UBC Volume 3
t  = .298 (in) see table 23-2-H of 1994 UBC Volume 3
e = .031 x 1.2 =.037  see Table 23-2-K; 20% increase for non-structural
I)
D = 1/32 (in)
X = (ft) average distance between chord splices (usually 20')

There are four different areas that contribute ato diaphram deflection.
They correspond to the four sections in the formula above.
They are as follows:

Deflection  = bending + shear + nail slip + chord splice slip

______________________________________________________________________

-----Original Message-----
From: David L. McCormick [mailto:DLM(--nospam--at)eqe.com]
Sent: Wednesday, May 19, 1999 10:16 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Unblocked Plywood Diaphragm Deflection Calculation

Let me know if you hear anything directly from anyone?

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