To: "Seaint list (E-mail)" <seaint(--nospam--at)seaint.org>
Subject: storage racks with partially restrained moment connections - wind frame analysis in high seismic zones
From: "Haan, Scott M." <HaanSM(--nospam--at)ci.anchorage.ak.us>
Date: Fri, 16 Mar 2001 14:56:01 -0900
In high seismic zones is using a wind-frame analysis an acceptible
approximate method for analyzing a moment frame? Is it an acceptable for
storage racks in wholesale retail warehouses in high seismic zones?
This is an approximate method for partially restrained moment frames, where
the beams are designed as simply supported and are large because of the
positive moments. The lateral force moments in the frame are then
calculated with an approximate portal method assuming a rigid frame.
The primary problem I see with it is that the gravity hogging moments on the
end columns are neglected and are not combined with lateral moments. Also
beam gravity fixed moments are not combined with lateral force moments.
Also the earthquake axial loads from overturning are ignored [baseplate
fixed end moments do not add up to overturning moments].
I had a couple guys down in California tell me when they walk down an aisle
in a Home Depot, they run and another prominent designer tell me there was
no racking damage after Northridge. A nickel for some opinions.
Scott M Haan P.E.
Plan Review Engineer
Building Safety Division http://muni.org/building,
Development Services Department,
Municipality of Anchorage
phone: 907-343-8183 fax: 907-249-7399