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Re: Unbonded Seismic Bracing

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I think Dr. James Kelly of UC Berkeley knew who is specialized. I read UC Berkeley tested some and installed by some company to retrofit. I was in the class of Dr. Kelley's about this project.

vicpeng wrote:

Thanks Karl, however, my mail wasn't clear.  I'm interested in hearing from companies that have used the "unbonded brace" system in their retrofits.  I was incorrectly comparing it to friction damper systems as a similar method. But having said that, who manufactured the braces you used?  Here, there is also no prescriptive guide to the use of the damper systems, however, we have the code "out" that testing can be used to justify the system(s).  The developers and manufacturers here have their own data etc, and the few that have been installed have satisfied the respective Clients.  BC Building Corporation, Concorde University, etc have used the friction damper systems. Ed Haninger has corrected my impression of the brace, and I immediately finished reading the first of the articles i started on.  So I'm slightly wiser (?). 
Thor A Tandy  P.Eng, MIPENZ
Victoria BC
e-mail: vicpeng(--nospam--at) 
----- Original Message ----- To: 'seaint(--nospam--at)'Sent: Thursday, October 17, 2002 9:58 AMSubject: RE: Unbonded Seismic Bracing
 Yes, we did a  retrofit on a two story steel braces building damaged by the Nisqually Earthquake in Seattle. We inserted calibrated friction dampers calibrated for each individual brace.There is a firm in Tacoma WA who did the design.(there is nothing in the building codes that would give you  guidance on how to do it).-----Original Message-----
From: vicpeng [mailto:vicpeng(--nospam--at)]
Sent: Thursday, October 17, 2002 9:15 AM
Subject: Unbonded Seismic Bracing
I am reading articles about "unbonded seismic bracing" developed by a Japanese researcher, followed up by a New Zealand engineer, and subsequently used for an upgrade to the Psychology & Geography block at the University of Christchurch.  I understand that it has recently been accepted in the US as an acceptable bracing system.  It is essentially a "friction" type bracing (?).  I haven't finished my review of the detail, but it may be a rival to current friction dampers. Does anyone have on-site experience with this type of bracing? 
Thor A Tandy  P.Eng, MIPENZ
Victoria BC
e-mail: vicpeng(--nospam--at)
fn:Chung-Soo Doo, Ph.D.