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Title: '97 UBC section 2316 comparision to 2000 IBC section 2306

There are no restrictions on the 1.6 load duration factor in the 2000 IBC.

Sorry I didn't understand your original question.

Buddy Showalter, P.E.
AF&PA/AWC

***********

From: utej(--nospam--at)attbi.com
To: <seaint(--nospam--at)seaint.org>
Subject: Re: '97 UBC section 2316 comparision to 2000 IBC section 2306

Thank you for your response.  I do realize that the 1/3
stress increase is unrelated to the load duration
factor, CD, for wood. 

My original question was trying to help determine if the
2000 IBC allows a designer to use the 1.6 load duration
increase for wood for seismic loads where the 1997 UBC
did not allow a 1.6 load duration increase for seismic
loads for fasteners in wood if mode III or IV behavior
was not exhibited nor does the 97 UBC allow for the 1.6
increase for seismic for mechanical fastenings ('97 UBC
section 2316.2).  In addition, the '97 UBC stated that
the 1.6 wood load duration factor for wind was allowed
only when members or nailed or bolted members exhibited
Mode III or IV behavior.  It appears as if the IBC lets
a designer use the 1.6 wood load duration factor for
wind or seismic with no restrictions.  Is this correct?

Also, '97 UBC section 2316.2 states that when using the
1.6 wood load duration factor increase for either
earthquake or wind, it should not be combined with the
1/3 stress increase in section 1612.3 (this applies to
both the basic and alternate load combinations).  The
IBC appears not to have limitations on the use of the
1.6 wood load duration factor as the 1997 UBC.
> Here's my response to this posted in Oct. 2001. The archives show the full
> discussion.
> **********
> The 1/3 stress increase is totally unrelated to the load duration factor for
> wood. The 1/3 stress increase is a load combination adjustment factor that
> accounts for the reduced probability that two or more loads, other than dead
> loads, acting concurrently will each attain its maximum at the same time.
> such
> adjustments are applicable to all materials, but it unfortunately got
> incorporated on the resistance side of the equation rather than the loads
> side.
> it has been moved from the resistance side of the equation in ASCE 7 (and
> IBC)
> to the load side of the equation in the form of a 0.75 adjustment (inverse
> of
> 1.33). so, you are still permitted the adjustment, but it's now taken on the
> loads in accordance with IBC 1605.3.1.1.
>
> The ASCE 7 Commentary section C2.4.3 and NDS Commentary section 2.3.2.3 has
> more
> detailed discussion of this for those interested.
>
> HTH
>
> Buddy Showalter, P.E.
> AF&PA/AWC