Take a look at this product report, page 5 simple beam diaphragm values. Am I missing something or shouldn't there be different values depending on the load direction relative to the panel joints? I emailed with USG and they said that the testing was only done for one direction in the configuration shown. OK, great.... but lateral loads occur in other directions. Am I missing something?
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Diaphragm Shear Values - Structo-Crete
- Thread starter bookowski
- Start date
I'm not at all sure that I know what I'm talking about with this. However, I see that nobody's responded on this one and I refuse to leave a good engineer on the field of battle. At the very least, you'll get a bump out of my response.
There's no such thing as uni-directional shear in the context of a shear panel (diaphragm assumed incapable of providing axial stress resistance). It's the old pure shear element business from your Mohr's circle days back in university.
For this reason, I contend that you only need shear testing in one direction. It's similar to wood and steel diaphragm testing. Capacity will be governed by shear stress in one direction or the other but that governing capacity will apply to transverse loading applied in either direction. It's a mouthful, I know. Let me know if a sketch is required.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
There's no such thing as uni-directional shear in the context of a shear panel (diaphragm assumed incapable of providing axial stress resistance). It's the old pure shear element business from your Mohr's circle days back in university.
For this reason, I contend that you only need shear testing in one direction. It's similar to wood and steel diaphragm testing. Capacity will be governed by shear stress in one direction or the other but that governing capacity will apply to transverse loading applied in either direction. It's a mouthful, I know. Let me know if a sketch is required.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
- Thread starter
- #3
I will answer my own question in case anyone else is looking at a similar product/situation. After a lot of back and forth my original concern seems valid, they should be providing diaphragm values for various panel and blocking layouts similar to wood diaphragms. I spoke to marinoware and clark deitrich and sent them over the design tables and they both agreed that it was lacking. After numerous calls to USG I received various answers - there is zero assumed capacity in the other direction along aligned joints, it is the same value in both directions if you block it, it is probably a similar value in both directions if you block it but we don't have any data that we can provide - they suggested that I assume some reduced value (that I make up)... etc. etc. It seems that the product is not quite up to speed yet if you need to do any actual diaphragm analysis.
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