Forum Index > Trip Reports > Eureka Creek Footlog Bridge Completion, October - November, 2022
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iron
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iron
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PostSat Nov 12, 2022 11:07 pm 
Sculpin wrote:
Kim Brown wrote:
seems that if a load were at the top of the arch, the weight is distributed to each side of the arch; once the energy meets resistance at each end, it stacks up and creates a stronger support overall. The arch itself is the distributor of energy.
That's it! agree.gif A loaded spanning beam will always have regions in tension and regions in compression, so there is complexity there, but your words indicate that you intuitively understand what is happening. Thanks for the swell certificate, KarlK! I may well cash it in.
for a shallow arch, the horizontal thrust forces required to 'pin' it into place to cause it to act as a beam-column approach infinity. you do not have that here in this case or any other log bridge, ever. i promise you: there is no impact to strength or stiffness because of whatever minor arch is in place.

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KarlK
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KarlK
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PostFri Nov 18, 2022 1:32 pm 
Iron and Hofbeck are in agreement on this. I even had a M.D. friend, Dr. Ron, whom I worked with in a former life, email me to opine in favor of the Iron-Hofbeck position. Dr. Ron was an electrical engineer before becoming an endocrinologist and statistician. Unrelated aside: We considered starting the Ron and Karl Data Massage Parlor (motto: p less than 0.05 or your money back!) but thought the better of it. smile.gif

Karl J Kaiyala

Brushbuffalo, Carbonj
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Bowregard
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PostFri Nov 18, 2022 3:43 pm 
I think the low arch question has been put to bed. No offense to your MD friend but I would listen to the structures folks over EE and MD credentials for something like this. My degree was Mechanical Engineering and though we all took Physics and Strength of Materials other disciplines seldom deal with arches (low or high) very often. And I guess it was just my wishful thinking that us engineering folks became less geeky by comparison when Computer Geeks came along. I do have another question about the species selection. Carbonj stated Yellow Cedar as a first choice over Red Cedar and Fir. I am very familiar with Red Cedar and Fir (woodworking hobby) but have not worked with Yellow Cedar much. I read that it is not a true cedar but actually a Cypress and that it is more dense and hard than Red Cedar (and Carpenter ants avoid it). Is it the strength that makes Yellow Cedar preferable to Red Cedar or is it actually more resistant to rot and bugs?

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Carbonj
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PostFri Nov 18, 2022 6:15 pm 
Yep yellow cedar is more dense and rot resistance, and its beautiful. I would love to have a floor of it. If you ever get the chance check out a carving Bill Reid did called the raven and first men, its in Vancouver at the UBC Museum of anthropology.

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iron
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PostTue Nov 22, 2022 12:45 am 
yellow cedar also splits terribly (for firewood) and doesn't season as well as red cedar, which is awesome for splitting.

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Malachai Constant
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PostTue Nov 22, 2022 7:50 am 
You cannot easily make shakes and shingles out of yellow cedar. doh.gif

"You do not laugh when you look at the mountains, or when you look at the sea." Lafcadio Hearn
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Carbonj
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PostTue Nov 22, 2022 8:01 am 
My old boss pointed out a downed yellow cedar they used for decking in cataract creek area. I was able to split a piece with a plastic bucking wedge for a repair. Very rare.

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Brushbuffalo
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PostTue Nov 22, 2022 11:35 am 
The roof replaced on the Mebee Pass Lookout in 2013 (was that the year, KarlK?) was yellow cedar. The roofer considered to a great opportunity to use that species for shingles.

Passing rocks and trees like they were standing still
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KarlK
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PostTue Nov 22, 2022 11:51 am 
Yep 2013 -- Dave Tucker (a pro) did the roofing -- there were a lot of pros on that project. I posted a TR on this complete with pictures of the roofing. https://www.nwhikers.net/forums/viewtopic.php?t=8007562 By the way, we've been informed that the Methow Valley RD has obtained funding to replace the bridge over Granite Creek, and DonH, Mike Liu and I will start reclearing the East Creek trail next summer. Biggg wood in there, hoo boy, and a lot of C-level bucking for sure.

Karl J Kaiyala

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