Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Required wall attachment to a flexible diaphragm.

[Subject Prev][Subject Next][Thread Prev][Thread Next]

These values apply to all components of diaphragm to wall attachment
including wall ties, sub-diaphragms and continuity ties.

The values should be modified per 1633.2.8..4 &5.  For wood components
these values may be reduced by WSD factor (1.4) and 0.85, if framing member
sizes have a minimum of 2.5 inch net actual thickness.

By taking all the above noted factors into consideration, this value will
reduce to 0.65Wp for wood members 3x or larger.  This value includes the
near source effects as well as better classification of soil type.  The
corresponding 1994 UBC value woudl be 0.45 Wp (for the middle third of

"From the desk of Joe Otto" <jmo_engineering(--nospam--at)> on 08/26/99
02:35:53 PM

Please respond to seaint(--nospam--at)

 To:      "Seaint@Seaint. Org" <seaint(--nospam--at)>            
 cc:      (bcc: Niaz A. Nazir/EQE)                            
 Subject: Required wall attachment to a flexible diaphragm.   

The 1997 UBC Section 1633. indicates the values for Rp and Ap of 3.0
and 1.5 respectively should be used for elements of the wall anchorage

What are the components of the wall anchorage system that these values
to?  Is it the attachment of the wall to the diaphragm.  Or does this also
include the subdiaphragms and cross-ties?

if hx = hr ==> Fp = ap*Ca*Ip/Rp*(4Wp)
               = 1.5 * (.44*1.2) * 1.0 / 3 * 4 * Wp  = 1.06Wp

This seems high to me.  If anyone could take the time to clarify/confirm
this, it would be appreciated.

Thanks in advance.

Joseph M. Otto, PE
Ireland Engineering
Fremont, CA