Load Duration for 5 PSF Interior Partition 4

[L_Bey]

I'm designing an interior wood bearing wall to support 3 floors and a roof, as well as the standard horizontal load of 5 psf. The code does not specify exactly what this horizontal load is, and how it should be combined with other loads. Since this is a wood wall, the duration factor of the horizontal load also makes a significant difference in design. We've generally assumed that the horizontal load is to account for general internal pressure effects such as opening doors as well as any lateral loading from leaning on the wall.

If the interior wall load is treated as a transient load, and given a duration factor of 1.6 for a 10 minute duration, it would seem like it shouldn't apply in full combination with other live loads. But if it is combined at a 1.0 factor with floor live loads would the 1.6 duration factor still be correct for the stud design?

How have other people handled interior wood bearing walls with wall pressure?

 

[msquared48]

Dik...

Years ago I worked on the design of the prison in Monroe, wa. The walls were precast concrete, and all the connections had to be hidden. The connections were not as flimsy as you describe, but when you have all the time in the world, things do happen.

Mike McCann, PE, SE (WA)

 

[dik]

I seem to recall one of Ron's comments... meaner than a junk yard dog that chews concrete... or something of that ilk.

Dik

 

[Celt83]

L Beyer:
you may want to double check your stud capacity assuming you've got about a 9'4" stud height and 2x4 SPF#2 your allowable load would only be about 1,677 lbs considering the 5 psf as a live load and 2.0 duration factor.

We used to look at this as a internal wind pressure with Cd of 1.6 and have recently started considering it as a live load we found some commentary that is is there to capture incidental loads. I could see an argument that the wording of the 5 psf load in IBC makes it sound like in the absence of any other load it needs to carry 5 psf laterally not necessarily in tandem with the design loads, the clause seems to really be in place for non-load bearing partitions so someone leaning or bumping into them doesn't cause them to fall over.

http://files.engineering.com/getfil..._Post_Capacity_NDS_2005_-_Lateral_as_Live.pdf

 

[Jerehmy]

We have the 2006 IBC commentary which states the following for Section 1607.13:

"The minimum lateral live load is intended to provide sufficient strength and durability of the wall framing and of the finished construction to provide a minimum level of resistance to nominal impacts that commonly occur in the use of a facility, such as impacts from moving furniture or equipment, as well as to resist HVAC pressurization."


Maybe this will help your decision on Cd.

 

[L_Bey]

Celt83 - we're definitely using double studs for the bottom 2 floors - there's just no way to get the capacity we need in a 2x4 wall without. It was more of a question of have we considered the loads appropriately and do we need to drop the stud spacing as well.

 

[Celt83]

Jerehmy:
We've used that commentary to rationalize Cd of 2.0 and treating it as full DL+LL and full lateral LL rather than using the 0.75 factor for two transient loads in the past.

L Beyer:
Gotcha we've had a few walls here that pushed to LSL's especially in the 5 story wood jobs that are getting more common, unless we can get buy in on 2x6 interior walls early.