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type 5 non parallel irregularity in buildings

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moonela

Civil/Environmental
Jun 28, 2023
1
Hello, I am looking for a solution for type 5 non parallel irregularity. another solution instead of 3D modeling to response below comment:" The structure has a Type 5 horizontal structural irregularity (nonparallel system) per ASCE 7-16 Table 12.3-1. Please clarify how the requirements of §12.5.3 and §12.7.3 are met. Include calculations."

If anyone have experience about this type of irregularity in wood building please guide me.
 
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It sounds like the author of the comment wants some assurance that you understand those provisions, you have a 3D model which accounts for the manner in which the diaphragm distributes the loads to the LFRS, and you have combined the loads from the orthogonal directions properly.
 
It's been a while since I've looked at this but isn't the method of concurrently considering 30% of the orthogonal direction load in addition to your 100% primary direction load a way to deal with this? If so, I'd spin a version of your lateral calcs that gives some kind of nod to that.

Of course, in my heart of hearts, I'd really like to respond to the reviewer with "Surely, given the uncertainties involved in light frame building design, this level of rigor is ridiculous?". That would get you nowhere of course. So don't attempt that.
 
KootK said:
Surely, given the uncertainties involved in light frame building design, this level of rigor is ridiculous?".

I am sure many of us have dreamed of writing this response lol.

If its a rigid diaphragm building with any eccentricity of mass/stiffness then 100% / 30% for orthogonal effects can (and should) be reflected in the design of all the lateral resisting elements.

If its a flexible diaphragm building you can still have some elements that participate for loading in each orthogonal direction. For example a shared shear wall compression or tension chord.

I regularly do the 100%/30% combination on these corner elements.
 
I have always wondered what the code intended with requiring a 3D representation of a diaphragm, specifically a wood diaphragm, which to my knowledge there doesn't existing a software to analyze.
 
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