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Re: 2000 IBC v 1999 UBC code question

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George:

To answer your question...it is my understanding that the 1/3 stress
increase never had experimental data to back it up.  It simply was "always
done that way".  Now, the IBC has taken that option out even though the
individual referenced standards allow it (AISC, ACI, etc...)  Wood is still
allowed because it is unlike the other materials because in its design
criteria the allowable stresses are low and then bumped "up" by factors such
as 1.15 and 1.6 depending on the criteria.  This is due to the fact that
every wood member is different.  Other materials such as steel start with
higher stresses (because of the better quality control of the material) and
are reduced.

To answer your question regarding the Simpson ties...you better ask them,
but my feeling is most of those connectors are governed by the connection
(nails, screws, etc...) and the failure is in the connection to the wood.
Consequently, for wood connections, these Simpson would not need to be
reduced since the stress increase is allowed for wood.  However, if you were
using these connectors in light gauge steel design, they would have to be
reduced.

Jeff



----- Original Message -----
From: "George Richards P.E." <george(--nospam--at)borm.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, October 29, 2001 1:51 PM
Subject: 2000 IBC v 1999 UBC code question


> Fellow Engineers:
>
> I am reviewing the impact the IBC will have on how we design out West.
>
> Using 1997 UBC Alternate Basic Load Combination 1612.3.2 we are allowed a
> 1/3 stress increase for wind or seismic only loading regardless of if the
> material is wood, steel, or concrete.
>
> Using 2000 Alternate Basic Load Combination 1605.3.2 we are NO LONGER
> allowed a 1/3 stress increase for wind or seismic only unless specifically
> given in the material section.  This means wood only.
>
> First question:  Did I read this correctly?
>
> Second question, {mostly for those of you in Texas where I know that every
> home is Engineered :)} where the IBC has been adopted are you still using
> Simpson numbers or since they have also included a 1/3 increase on steel
are
> you down grading them?
>
> Thanks in advance.
>
> George Richards, P. E.
>
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