Dave,
Being in the same seismic country as you, yes, we are finding that our seismic load levels have decreased in general. However, due to the relatively arbitrary nature of the old “zone” method, our structural team is not uncomfortable using the new lower values. Also keep in mind that some lateral systems have greater detailing requirements than previous codes (depending on your SDC), thus increasing your “R” value and decreasing the seismic force level.
HTH,
Doug Mayer, SE
Structural Engineer
TaylorTeter
Partnership
7535 North Palm Ave., Suite 201
Fresno, CA 93711
(559) 437-0887 Ph.
(559) 438-7554 Fax
From: Dave Adams [mailto:davea@laneengineers.com]
Sent: Friday, June 06, 2008 9:44 AM
To: seaint@seaint.org
Subject: Seismic loads using ASCE 7
Happy Friday, everyone!
One of the things that we are sort of struggling with here (old “zone 3” country) is that we are finding seismic loads via ASCE 7 wind up being less (sometimes uncomfortably) than what we used to calculate using the 1997 UBC. As a result, we’ve sort of adopted our own internal “company minimum seismic coefficient” that we are comfortable with. Are most people discovering the same thing and what are your thoughts?
Thanks!
Dave K. Adams, S.E., P.Eng.
LANE ENGINEERS, INC.
979 N. Blackstone Street
P.O. Box 1059
Tulare, CA 93275
Direct Line: (559) 688-5263
Direct FAX: (559) 688-8388
E-Mail: davea@laneengineers.com
Web: www.training4engineers.com
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