Bar-joist type beam for a loft

[Salty]

I made this beam for a loft in my shop. It spans 26' 9" and is 12" tall. I built it out of 4 pieces of 1 1/4"x 1 1/4" x 1/8" angle and a piece of 3/8" rod that I bent back and forth at 90 degree angles. I had to splice every piece so that I could get it to the right length. I am not a engineer but I welded it with a 3/4" crown and the way it sets now it still has a 3/8" crown it does not flex it is very solid. Now I have a place to put more stuff!
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[A/C Guy]

I built a similar loft in my shop last week. Mine spans 38' 8" and I made it 10' deep. I considered a joist design like yours, but then I chose to simply put 4 posts under the 2 x 8's.

I like your open design. I may copy that for my next 2 storage lofts on the sides of the shop. They will be 4' deep by 34' long, so I don't want to use posts as they will interfere with the work tables under them.

Have you considered adding a couple light fixtures in between the floor joists?

[shawn]

looks good

[Salty]

I built a similar loft in my shop last week. Mine spans 38' 8" and I made it 10' deep. I considered a joist design like yours, but then I chose to simply put 4 posts under the 2 x 8's.

I like your open design. I may copy that for my next 2 storage lofts on the sides of the shop. They will be 4' deep by 34' long, so I don't want to use posts as they will interfere with the work tables under them.

Have you considered adding a couple light fixtures in between the floor joists?

Yes I have, eventually I will get some light under there, I really need it over the saw so I can see what I am doing. But right now I seem to spend my spare time learning to weld on the new PT250EX. Good luck with your new additional overhead storage area.

[sm95m]

I made this beam for a loft in my shop. It spans 26' 9" and is 12" tall. I built it out of 4 pieces of 1 1/4"x 1 1/4" x 1/8" angle and a piece of 3/8" rod that I bent back and forth at 90 degree angles. I had to splice every piece so that I could get it to the right length. I am not a engineer but I welded it with a 3/4" crown and the way it sets now it still has a 3/8" crown it does not flex it is very solid. Now I have a place to put more stuff!
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One thing you need to bare in mind is a joist like this generally have the top chord fully braced by decking, In your case top chord buckling is limited only by how well you attached your ledger - kind of a complicated analysis. Also the bottom chord is not really meant for loading. If you check out the Steel Joist Institute web site you should find some info on loading joists.

[Canada]

From what I can see that trust was built for some serious floor loading. That trust looks very similar ones we have in boiler room floors. They support a steel deck with a 4" concrete on top on 24" spacings. I would suspect it can carry a fairly heavy load. My only concern is with the attachments to the wall and the bearing surfaces on each end of the truss. Our building codes (up here) typically require a minimum 3" load bearing surface. I would suspect your building codes will be fairly similar. It appears your bearing those loads on a 1 1/2" bearing surface? I am not sure how the floor joists are attached to the block wall, but blocks are very weak in respect to horizontal loading or pull out resistance. I would be inclined to have these checked before adding any additional weight. I am not criticizing your workmanship simply pointing out possible areas of concern from a structural stand point.

[aaxiss]

nice job there, you my friend just gave me a great idea for a soon to be travel trailer/carport cover project.

[sm95m]

One thing you need to bare in mind is a joist like this generally have the top chord fully braced by decking, In your case top chord buckling is limited only by how well you attached your ledger - kind of a complicated analysis. Also the bottom chord is not really meant for loading. If you check out the Steel Joist Institute web site you should find some info on loading joists.

for Sh*ts and giggles I modeled on the computer with a 50#/ft dead load and a 100#/ft live (storage) load and the 3/8" rod is overstressed as much as 145% - especially at the ends where the web members do most of the work. if you look at a manufactured bar-joist the web members are small but bigger near the supports. heaviest loaded diagonal is the last one on each end. Deflections are OK @ full 150 PLF load