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RE: Tiltup Bottom Connections

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Thanks Fred.  But with all due respect to the code and the groups studying failures, according to Sec. 2302 of the l927 U.B.C. engineers are supposed to design buildings to support all loads that they will encounter;  I don't think that has changed.  If one turns off their computer long enough to do a free body diagram of the wall with a lateral force applied, they will see that it has to have lateral resistance at the only two places where it comes in contact with horizontal members: at top and bottom.  Therefore you should consider how that force is taken care of at the bottom as well as the top.  It is pretty easy to make sure that force can go into the slab in most instances at little expense; and if that can't work, another load path can be devised.  I am not going to wait until enough failures are properly documented to close my eyes to what I learned as a sophomore in college.
-----Original Message-----
From: Fred Turner [mailto:turner(--nospam--at)]
Sent: Tuesday, February 20, 2007 9:50 AM
To: seaint(--nospam--at)
Subject: Tiltup Bottom Connections

Jake & Richard,
I suggest you read "1994 Northridge Earthquake Buildings Case Studies Project, " CSSC 94-06. Case 1.15 by Bob Lyons and Ken Gebhart compares the performance of three tiltups and has a brief description of the influence of panel base fixity on the wall-to-roof connection demands. It concluded that lateral bearing against earth at panel bases permitted excessive deflections at the roof. It suggests that further study of this matter be conducted. While there were no failures at the panel-foundation interface in these buildings, base fixity appeared to contribute greatly to panel anchor forces and to overall performance. Copies are available from the Commission for $50, but the report is also in most earthquake engineering libraries at major universities.
By the way, SEAOC recently formed a Post-Disaster Performance Observation Committee to more systematically collect and evaluate performance to assist practicing structural engineers. If you are interested, I'd be happy to connect you to them.

Fred Turner, Staff Structural Engineer, California Seismic Safety Commission, a public policy advisory agency, Turner(--nospam--at), 1755 Creekside Oaks Dr. #100 Sacramento, CA 95833 Phone: 916-263-5506 Ext. 227 or 916-263-0582 Fax: 916-263-0594