IBC 06-Table 2306.3.1

[WWTEng]

The question I have is about the allowable shear loads shown in this table. I just want to make sure that these are actual allowable values and do not need any reduction for shear loads on the diaphragm due to wind. I was talking to another engineer and he indicated that he divides these numbers by 2.0. I couldn't find anything in the footnotes that suggests doing that.

The other question I have is about the thickness limit for structural I grade. The table lists panel thickness of up to 15/32. There is no listing for 5/8 & 3/4 thick panels. Why is that?

Thanks,

 

[woodman88]

If you read the section on Wood Diaphragms (Section 2306.2 in 2009 IBC or Section 2306.3 in 2003 IBC, sorry but I do not have a copy of the 2006 IBC) you can increase the table loads 40% for wind design.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[msquared48]

Whereas if seismic controls the design of the walls, you have to apply the 2h/d factor for shorter walls. Perhaps he uses a lot of shorter aspect walls and just reduces by .5 as a matter of course.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[woodman88]

In regard to your thickness of shear panels in shearwalls question, in my opinion, the minimal increase in shear of larger than 1/2” plywood/osb on shearwall is over shadow by the large increase in shear allowed by adding shear paneling to each side of the wall.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[RWW0002]

I would guess that his 2.0 factor comes from the fact that NDS SDP for Wind and Seismic tables (from which IBC 2306.3.1 is derived) gives shear panel capacity as a nominal shear capacity which must be divided by an ASD reduction factor of 2.0. IBC 2006 gives shear capacity as allowable shear capacity (thus the values have already been reduced.)