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Re: Required wall attachment to a flexible diaphragm.

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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
diaphragm).








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

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


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








The 1997 UBC Section 1633.2.8.1.1 indicates the values for Rp and Ap of 3.0
and 1.5 respectively should be used for elements of the wall anchorage
system.

What are the components of the wall anchorage system that these values
apply
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