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Re: Load Paths

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Bill,
I looked at it - it is the old hybrid shearwall. They have just introduced a new light-gauge steel panel similar to the Hardy Panel and this may resolve your issues related to out-of-plane forces. I understand your concern, and you can limit your H/t ratio by trying to analysis out-of-plane buckeling - it's just that with few have done a sucessful analysis and there is nothing in the ICBO Seismic Design Manual that covers this. I just don't have faith in it as our last debate suggested that the king-post supporting openings in excess of 8'-0" won't work in bending. However, there is not recorded information of failures even if the numbers in the strong direction don't calculate out. I don't have a problem stamping my work as I figure that the Seismology committee is anything but an expert on light frame construction and has done more harm than good to the methodology. The answer is simply to compare prescriptive conventional framing to engineered design. The walls can be designed to 10-feet in conventional construction but may not calculate in full-compliance. So regardless of whether your stamp is on the project or not, there is a strong argument probably coming from NAHB-RC to support taller walls subject to out-of-plane forces. Go figure - I trust my judgement first before I trust the opinion of the Seismology committee on out of plane forces - they have been known to be wrong :>) As to potential liability, one way or another you end up fighting them using the conventional construction argument in your favor. The issue is life safety and major structural damage - the same prevention that is suppose to be protected by conventional construction.
Dennis


Bill Allen, S.E. wrote:

Dennis -

There was no attachment to the message but a link to a jpg file on my
website. Don't worry, it's safe to open a jpg as you know.

Here's the link again: http://www.allendesigns.com/images/strongwall.jpg

I understand your argument about items in a wood framed structure which adds
to the stability and are not usually considered in the analysis, I'm just
not willing to put my stamp on that kind of detailing. After all, if
something does fail, what's my defensible position?

Anyway, look at the picture and we can talk more.

Regards,
	
T. William (Bill) Allen, S.E. (CA #2607)	
ALLEN DESIGNS	
Consulting Structural Engineers	
http://www.AllenDesigns.com	
V (949) 248-8588	 .	 F (949) 209-2509	




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