Return to index: [Subject] [Thread] [Date] [Author]

RE: Overturning check

[Subject Prev][Subject Next][Thread Prev][Thread Next]
The problem is that UBC does not specifically say that when this load
combination is used the factor of safety can be 1.0. The load combination
itself implies presence of a safety factor, but I have seen reduced dead
loads used with a safety factor of 1.5 against uplift. So to many, the
presence of a factor at the load combination level may not mean it is
directly accounting for a safety factor.

Ghassem. 

-----Original Message-----
From: Ed.Haninger(--nospam--at)fluor.com [mailto:Ed.Haninger(--nospam--at)fluor.com]
Sent: Wednesday, February 02, 2000 9:06 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Overturning check




Allowable load combinations are used to check overturning.  There is no code
requirement to use a stability ratio over 1.0 for seismic.   This is
discussed
in 1997 UBC section 1629.1  The allowable stress combinations of section
1612.3
are used.  By the way, a combination 12-16-1 has been added to the UBC:
0.90 D
+ E/1.4

Ed Haninger
Fluor Daniel
Aliso Viejo, CA





"Khosrownia, Ghassem SPK" <GKhosrownia(--nospam--at)spk.usace.army.mil> on 02/02/2000
08:39:29 AM

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

To:   "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
cc:    (bcc: Ed Haninger/AV/FD/FluorCorp)

Subject:  RE: Overturning check



Bill,

Where do you get the safety factor from? I don't believe the UBC actually
gives any numbers for seismic OT. I have heard that FOS of 1.0 is adequate
for resistance against EQ induced overturning forces mainly because these
forces are not steady and they are reciprocating. What do you think?