A couple of recent posts wanted info on how to calculate bolt spacing on built up beams where the extreme tension member is in shear relative to a basic wooden beam. A lot of web references for “built up beams’ are talking about simple side by side setups – side by side setups do not rely on bolted connections to handle shear along the length of the beam axis.
Here are a few references, as many have said, if you don’t understand the equations and the practicalities of these presentation, it may be to one’s benefit to hire it done (anathema to DIY ears, but may be less than the effort needed to learn all the below)
1. Wood box beam
http://tardis.union.edu/~hsiaoa/hwsol6.pdf
2. Some beam basics
http://www.du.edu/~jcalvert/tech/beam.htm
3. How about split timbers??
http://www.fpl.fs.fed.us/documnts/pdf1996/ramme96a.pdf
4. Built up beam shear discussion
http://www.galaxyscientific.com/agingaircraft2002/SESSIONS/5/5A2_CHSU_PPT.PDF
5. Here are 2 fairly complex papers for reference , getting into detail and complexity, way past most anything in homebuilding.
http://www.galaxyscientific.com/agingaircraft2002/SESSIONS/5/5A2_CHSU_PPT.PDF
6. Lastly, even though flitch paltes are a waste of good steel, this is a ‘cookbook’
Replies
All your info is worthless if you don't have any idea how to figure the load a beam is carrying.
Here's a PDF file that can provide some insight into that.
Introduction to Load Paths and Wood Design:
http://www.beamchek.com/AcrobatFiles/IntroLoadPath.pdf
Thanks for the links. I don't have time now to read them all, but I bookmarked them. The galaxyscientific one is duplicated in items 4 & 5 -- did you mean to put a different link in one of those places?
-- J.S.
my error, sorry for the duplication
you're bringing back the "pain" of freshman intro to engineering - I'm getting a headache
(and we were the last freshmen class to have to learn sliderules - yeah, I'm old)thanks for the links - just looked them over quickly - never considered it but why are flitch paltes (plates) a waste of steel?
flitch as waste of steel =way too much steel in centerline shear, same reason I-beams are mostly flange, small web.
kind of thought that might be something like that - compression and tension loads on 1/2 inch wrapped in wood with nothing to counter act deflection
> flitch as waste of steel =way too much steel in centerline shear, same reason I-beams are mostly flange, small web.
True. The same criticism applies to solid sawn lumber, or any beam consisting of uniform material with a rectangular cross section.
Cost of the beam material per pound of load over a given span isn't all there is to it. Labor to install the beam and to attach joists and stuff to it also figure into the decision. Sometimes if the load is small, the span is short, and the cost of lumber is low, it isn't even worth while figuring it out.
-- J.S.