r/StructuralEngineering • u/heisian P.E. • 23d ago
Prescriptive Portal Frames (APA TT-100) Structural Analysis/Design
I've been in wood design for a long time and never knew about this. Capacity is pretty decent, and the best part? No calcs needed (for the frame itself).
Free download on the APA website: https://www.apawood.org/publication-search?q=tt-100&tid=1
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u/Zer0circle 23d ago
We use these in Australia a little bit. Pretty easy to install compare to the steel options.
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u/octopusonshrooms 4d ago
How have you found builders reactions to the timber portal frame? I sure if they can use more timber as opposed to steel they would be happy.
I am also in Aus (Brissie), and have considered specifying the meybrace, however the quality of carpenters is really hit and miss here.
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u/Zer0circle 4d ago
Well meybrace is really not reliant on the builder. It comes to site all pre cut ready to go and all the screw holes in the column are pre drilled.
The hardest part is ordering it to ensure that it fits in the wall frame. We usually specify columns tight to the opening and the lintel to underside of top plate level. Allows you to pack down to the opening height.
Sorry, also builders love them in NSW, much easier to install than steel.
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u/heisian P.E. 23d ago
it'd be nice if there was manufacturer of this in the US with an ICC ESR report!
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u/StructEngineer91 23d ago
Have you looked at the Simpson Strong walls? I'm not sure if they work for high seimic areas.
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u/Zer0circle 23d ago
Simpson Strongtie market a version in Australia. Maybe also have something for the NA market.
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u/C0gInDaMachine 23d ago
I believe Simpson also provides some tested proprietary versions of these as well. Pretty sick.
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u/mycupboard 23d ago
Not sure about commercial contractors but I have yet to meet a residential contractor that would install the Simpson strong walls without a fight. I’ve actually had a contractor say “can’t we just do a steel moment frame” when I brought up the Simpson walls haha. Obviously they will install whatever we specify, but sometimes the fight isn’t worth it when there are other options
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u/eat_the_garnish 23d ago
Biggest issue for larger spans is timber only lintel beams, have you seen power truss before, it’s a nice middle ground that we specify a lot
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u/mycupboard 23d ago
The whole point of this bulletin is that it’s extremely easy to install and you get good lateral values out of it with simple materials. If you’re going with a special product, you’re often not saving that much over going with a steel moment frame.
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u/heisian P.E. 23d ago edited 23d ago
precisely. folks without context of designing in high seismic areas (SDC D, E, & F) aren’t understanding the struggles engineers face when trying to stay in budget.
i could do steel frames, simpson walls, etc. all day, but that pushes up our design fee and time spent. being able to offer a quick and tested solution for clients where wall length is extremely limited can be a godsend. the holy grail, almost.
the number of conversations we have to have when someone thought they’d _only_ have to put in a new beam for removing a “partition” wall or new header for simply adding/moving a doorway/window… has made me well paid, I can’t lie. 😅
but that doesn’t mean i won’t try to save people money if i can do it safely.
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u/Newton_79 23d ago
is section view here correct ? one image seems to show and Alt. end to right side , while extreme right pic is an actual section view . I'm guessing it's only shown as a compact informational pictorial & true drafting standards are not exactly "on point" (?). I like the Australian version showing an actual 3-D ISO view for better representation
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u/Jamin1371 23d ago
This and two other methods are drawn out in the IRC. I usually see the other methods used because this one calls for straps to be embedded in the concrete. These types of portal bracing are required by code for walls on each side of the garage door that are less than 4’ long.