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Re: Wood interior wall studs

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1.0 for the people on the floor, 1.6 for the additional "impact" for the bodies diving off the stage. Sorry haven't designed any mosh pits lately.

Joe
----- Original Message ----- From: "Haan, Scott M POA" <Scott.M.Haan(--nospam--at)poa02.usace.army.mil>
To: <seaint(--nospam--at)seaint.org>
Sent: Friday, July 13, 2007 1:56 PM
Subject: RE: Wood interior wall studs


Do you design a mosh pit floor with Cd=1.6 or 1.0?

-----Original Message-----
From: Joseph R. Grill [mailto:jrgrill(--nospam--at)cableone.net]
Sent: Friday, July 13, 2007 12:50 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Wood interior wall studs

"impact" being an important descriptive word, therefore, 1.6 Cd.


----- Original Message -----
From: "Andy Heigley" <aheigley(--nospam--at)jgaeng.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Friday, July 13, 2007 1:45 PM
Subject: RE: Wood interior wall studs


Actually the 5 psf is due to HVAC.

Here's and excerpt from the IBC Handbook:

"According to BOCA/NBC, the requirements of this section, reproduced from
the 1999 BOCA/NBC section 1606.9, are intended to provide sufficient
strength and durability of the wall framing and wall finish, so that a
minimum level of resistance would be available to nominal impact loads
that
commonly occur in the use of a facility and to HVAC pressurization."



Andrew Heigley, PE



-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan(--nospam--at)poa02.usace.army.mil]
Sent: Friday, July 13, 2007 4:25 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Wood interior wall studs

I think the 5 psf is intended for people slam dancing on the walls - not
for
pressure from HVAC.  The IBC has the 5 psf in the Live Load section. The
97
UBC says the 5 psf is "L" and does not need to be applied with wind or
seismic.

I would use the 1.15 Cr and 1.0 for Cd for the 5 psf.

-----Original Message-----
From: Joseph R. Grill [mailto:jrgrill(--nospam--at)cableone.net]
Sent: Friday, July 13, 2007 12:16 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Wood interior wall studs

There is also repetitive member increases in bending.  15% usually, but
the
code allows 50% if a wind load.
Joe Grill

       ----- Original Message -----
       From: Jordan Truesdell, PE
<mailto:seaint1(--nospam--at)truesdellengineering.com>

       To: seaint(--nospam--at)seaint.org
       Sent: Friday, July 13, 2007 1:07 PM
       Subject: Re: Wood interior wall studs

       I do a lot of wood, and here's my take:

       The 5psf should be at a Cd of 1.6.  Why? Unless I have an
intentionally pressurized room (which is not the case here), there is no
possible way that common construction techniques can _maintain_ that kind
of
pressure differential over an extended period of time, and if you have a
constant load (say, a commercial kitchen with doors that seal
tight...right...) making the pressure differential then the HVAC engineer
should already be providing makeup air in that area.  The building code
can
call it a "live" load all it wants, but the actual duration of load will
never reach 10 years in the 50 year design life of the building.

       Roof live load should be given a Cd of 1.25; snow is 1.15.

       I don't recommend a loadbearing wall of 10' in height be made of
2x4s. Why? Because the walls will not be sheathed before the floor joists
are
set into place. The code limits the L/d ratio to 75 for construction, and
a
10' 2x4 has an L/d of 80. The contractor cannot build the wall unless he
plans on bracing every stud without violating the code.

       And, for the record, I agree with Don that 2x4s 10 feet long look a
lot like spaghetti. And as a bearing wall they give me the willies. My
answer
to such a request is normally to do it as designed, or provide another PE
to
seal off on the change with full calculations, and provide me with a full
release of liability should anything happen.  I've never been taken up on
the
offer.


       Jordan


       Andy Heigley wrote:

               Everyone:

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               Thanks for your responses...

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               Here are my responses to some of your questions back:

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               *       I would design for LL and LLr if the wall were
supporting both the floor and roof loads.

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               *       I am designing to ASD.

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               *       I guess I'm a little leary of using the Cd of 1.6
for
this reason.  The duration factor is applied to both bending and axial
capacities.  Applying 60% more to the allowable axial stress makes a huge
difference.  And if you have a 4 story building, for example, you are
going
to be approaching the capacity of the stud just due to DL and LL...  you
then
add a "little bit" of short term horizontal loading to the stud and
increase
the capacities by 60% seems non-conservative.

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               *       Scott:  I haven't found the rated wall design
reduction factors you've mentioned.  Can you tell me the code section that
is
in?

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               *       10'-0" high 2x4's... exactly why I initially called
for 2x6 stud walls, but the GC is flipping out about it... I get the old,
"I've been doing this for 30 years, and never had to do this before"...

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               Andrew Heigley, PE

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               <!--[if !supportEmptyParas]--> <!--[endif]-->

               <!--[if !supportEmptyParas]--> <!--[endif]-->



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