Bottom flange bracing of prefabricated wood "I" joist
Bottom flange bracing of prefabricated wood "I" joist
(OP)
For a roof with no ceiling on the long span prefabricated wood "I" joists soffit, what spacing would be required for bracing to the bottom flange? The span is about 36 feet. I would think that some horizontal bridging would be required to the bottom tension flange to stop the joists from twisting, but I have not found any such recommendation as yet. Is none required? Can anyone help?






RE: Bottom flange bracing of prefabricated wood "I" joist
See link below for some more info.
http://www.woodbywy.com/trus-joist/tji-joists/
RE: Bottom flange bracing of prefabricated wood "I" joist
RE: Bottom flange bracing of prefabricated wood "I" joist
Attached is a paper, which was for steel trusses, but the same fundamental issue exists no matter the construction type.
I would imagine something will be needed, as that seems like a long span, but following the concept in the paper something non-prescriptive can be determined.
RE: Bottom flange bracing of prefabricated wood "I" joist
I have never considered needing and tension chord bracing on beams or joists in general.
Wood floors typically have a ceiling, so restraint would be provided by drywall (not much). In some cases, unfinished basements don't have anything at all. If you need something, I don't think it is much at all.
For the 36' joist in question, you may want to consider either shortening the spans or providing something else to stiffen up the system and reduce vibration.
RE: Bottom flange bracing of prefabricated wood "I" joist
RE: Bottom flange bracing of prefabricated wood "I" joist
And on many of the unfinished basements I have seen there is 2x2 cross bracing at midspan or something similar.
RE: Bottom flange bracing of prefabricated wood "I" joist
RE: Bottom flange bracing of prefabricated wood "I" joist
2nd - if this is to be taken down, stored and erected again every year I would not recommend I-joist as they are at their weakest and most susceptible to damage during erection (and I can only assume during dismantling as well). How is the joist fastened to their supporting members? I don't know if you have ever nailed the top/bottom chords of these joist, but they split quite easily and I would not want the same joist nailed over and over again.
Is this an open canopy? You haven't given enough information. And it also depends on the manufacturer and size of joist. I still think your best bet here is to contact the manufacturer of the joist and get their opinion.
RE: Bottom flange bracing of prefabricated wood "I" joist
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Bottom flange bracing of prefabricated wood "I" joist
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Bottom flange bracing of prefabricated wood "I" joist
RE: Bottom flange bracing of prefabricated wood "I" joist
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Bottom flange bracing of prefabricated wood "I" joist
RE: Bottom flange bracing of prefabricated wood "I" joist
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Bottom flange bracing of prefabricated wood "I" joist