Glulam timbers vs multi-ply bolted boards
Glulam timbers vs multi-ply bolted boards
(OP)
Working on a design for my own pole barn. Not an area I work in so looking for standards and links to help me along. I am trying to determine structural improvements of a Glulam column for a pole barn vs just multiple timbers bolted together for the main poles.
Right now the design is setup with (4)2x8s on 8ft centers, bolted together on 2ft centers. I am trying to determine if there will be much structural advantage of using the glulam column in this instance. I am VERY concerned, being in tornado alley, about the main poles snapping off which would be next to impossible to repair.
I am also trying to decide on wood species for this. Cost IS a consideration but probably worth a few extra bucks to make sure these poles will out perform the rest of the building by a large margin.
Right now the design is setup with (4)2x8s on 8ft centers, bolted together on 2ft centers. I am trying to determine if there will be much structural advantage of using the glulam column in this instance. I am VERY concerned, being in tornado alley, about the main poles snapping off which would be next to impossible to repair.
I am also trying to decide on wood species for this. Cost IS a consideration but probably worth a few extra bucks to make sure these poles will out perform the rest of the building by a large margin.






RE: Glulam timbers vs multi-ply bolted boards
Go to the local utility company get a real pole! Those work. (but not for F5)
RE: Glulam timbers vs multi-ply bolted boards
RE: Glulam timbers vs multi-ply bolted boards
Local codes is designed around 90mph winds. That design would call for 3ply of 2x6s on 8ft center. There is no WAY I would build to the minimum 90mph specs. I am not trying to get the poles to hold through an F5 but I want to make sure the building skin fails and rips off or even the whole roof before those poles want to let go.
Living in "the zone" I very much realize I can only plan for so much and the rest is out of my hands. I know lots of people say to use I beam iron construction but those will twist up too in a serious nader and all the skin is removed. Wood is ideal here due to the interior build out.
RE: Glulam timbers vs multi-ply bolted boards
It's been a long time since I designed in wood, so can't offer any information beyond this.
RE: Glulam timbers vs multi-ply bolted boards
Glulams are EXPENSIVE. I use multiple 2x6s or 2x8s for 99% of my pole barn designs. Also, using a pneumatic air nailer will give you almost the same performance as bolts and be a lot cheaper and quicker!! You could shoot about 100 nails in the time it would take you to install two bolts. Fire them from both sides of the plies.
RE: Glulam timbers vs multi-ply bolted boards
80150x18, 3/12 pitch target (might have to use 4/12) with raised cross chord or scissor for increased head space. the truss will be the mother of all designs for sure. 80ft freespan WITH a more vaulted style truss could get interesting.
26ga metal pba metal, 25psf snow. Depending on what is found in the ground, 5ft will get buries so figure 23ft long columns.
I firmly agree about nailing the columns and planned to just add some bolts for added security but probably shoot 200 nails in each one which should really help with torsional stiffness and load sharing.
QUESIONS - I have two concerns with the post building. One I already mentioned which is the posts breaking off at the ground which is next to impossible to repair. I am not even sure if I designed it to break higher if there is anyway to fix that either...
Second is post protection from rot. ACQ for sure but I have heard that if you pour them in concrete, you will have a problem later. I DON'T want that problem! There is a company making post protectors and I think nothing more than plastic sleeves. I need to figure something out. I will have gutters but...
RE: Glulam timbers vs multi-ply bolted boards
http://www.cps.gov.on.ca/english/frameindex.htm
RE: Glulam timbers vs multi-ply bolted boards
Or, You could also design the building so it could be moved from the path of the tornado...
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Glulam timbers vs multi-ply bolted boards
BA
RE: Glulam timbers vs multi-ply bolted boards
BAretired - this would be 5ft, poured in concrete, with uplift locks on the poles, and a 1M lb 6" floor poured over the top. I have actually seen on picked and and moved in one solid piece but I am hoping my lock system will mitigate that concern.
RE: Glulam timbers vs multi-ply bolted boards
Considering the suddenness of pressure drop with any tornado, this may not be a realistic or feasible alternative though. I have never tried it, but it seems that if some of the walls and/or roof panels were allowed to quickly fail with a direct hit scenario, maybe the basic frame could be saved, depending on the mass of the debris being tossed around. Just a thought.
I wonder if anyone has tried this concept yet?
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com