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Author Topic: beam size calculator  (Read 1784 times)

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Offline coastlogger

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beam size calculator
« on: October 16, 2014, 02:46:28 PM »
I'm designing a wharf/dock for a neighbor and am using the round log table in the ff beam calculator section. Am stumped, sort of, on the "min dia to meet 1/360 deflection" Not sure if that's mid dia or top dia. Anyone here know? Silly question of course you know! Pls tell me!
Also, I'm pretty sure the "total load on beam" would be the load not including weight of beam but not sure on that either
And would the total load assume evenly distributed or concentrated?
Thanks for any/all help
clgr

Online Jim_Rogers

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Re: beam size calculator
« Reply #1 on: October 16, 2014, 03:39:00 PM »
I'm not sure which calculator you're using, can you tell me again?

Or provide a link?

Jim Rogers
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Offline coastlogger

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Re: beam size calculator
« Reply #2 on: October 16, 2014, 04:47:07 PM »
This is the link:http://www.forestryforum.com/members/donp/logbeamcalc.htm
I found it by googling I guess its not in the FF toolbox though maybe it could be added. Anyhow you can likely see where my questions arise from. Thanks
clgr
clgr

Offline Brian_Weekley

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Re: beam size calculator
« Reply #3 on: October 16, 2014, 05:34:19 PM »
The log calculator is in the FF Toolbox--Don'Ps calcs/Beam and Column Calculator/Log Beam Calculator.

It says this is for a uniformily loaded beam.  I assume the total load should include the weight of the log also.

It gives you three numbers: the "min" (minimum) diameter needed to meet each of the three criteria (bending, deflection, and shear).
e aho laula

Online Jim_Rogers

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Re: beam size calculator
« Reply #4 on: October 16, 2014, 05:40:03 PM »
Thanks for posting the link to that calculator. I haven't used that one ever before, as I don't work with logs, only making them into timbers.

So you asked: "on the "min dia to meet 1/360 deflection" Not sure if that's mid dia or top dia. Anyone here know?"
and: It would be the minimum diameter of the log. If that is the top then that is the top. Most likely it would be as logs are tapered from large at the butt to smaller at the top.

You asked: "I'm pretty sure the "total load on beam" would be the load not including weight of beam but not sure on that either."
and: I would have to assume it does not include the weight of the beam/log.

You asked: "would the total load assume evenly distributed or concentrated?"
and: The name of the calculator is "Uniformly loaded simple beam and Mid span log diameter".....
That should tell you that is not concentrated it is uniformly distributed and it is mid span diameters.

Hope that helps.

Jim Rogers


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Offline coastlogger

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Re: beam size calculator
« Reply #5 on: October 17, 2014, 11:22:07 AM »
Thanks for the help guys.
On the min dia for deflection,I fooled around with my approx dimension log(40 foot 12 inch cedar)did the calcs for a log,then for a similar square timber,compared results in bending and deflection etc etc. Im now of the "opinion" that the "min dia for deflection"refers to mid dia not smallest dia. I could prove this right or wrong if I could find my old log bridge design manual which is right where I left it Im sure.
Meanwhile Im making my stringers a bit fatter just to be on the safe side all around.Thanks again.
clgr
clgr

Offline giant splinter

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Re: beam size calculator
« Reply #6 on: October 17, 2014, 12:28:22 PM »
CLGR,
There is a link to a Ministry of Forests "forest service bridge design and construction manual" from British Columbia.
http://www.for.gov.bc.ca/hth/engineering/documents/publications_guidebooks/manuals_standards/bridge_manual.pdf

The University of Wisconsin has design criteria for timber and log bridges with information on calculating fiber stress and maximum allowable spans for various species of logs.
Hope this helps a little, it was not easy finding information on log bridges and logs when it concerns maximum fiber and limits of allowable spans under various live loads ...... this info is out there but difficult to find at least in my case.
roll with it

Offline beenthere

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Re: beam size calculator
« Reply #7 on: October 17, 2014, 01:15:12 PM »
I just recently read about some library archives that are specific to the timber bridge program that has been going the last 20 years. Might prove to be interesting data source for anyone interested. Apparently a large effort to organize a lot of resource material in one location.

http://maple.cybertoolsforlibraries.com/cgi-bin/CyberHTML?USDAFSA2Z+tbc
south central Wisconsin
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