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Moment Frame Question
- Thread starter XR250
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- #21
Passing through on my way to the stud/trimmer/header question..
I know it's shorthand, but that's NOT my detail. It's just a detail I happen to have laying about and I threw it up there for discussion. (Insert Donald Rumsfeld Joke/reference here). It's the drawing I had, not the drawing I wish I had.
This comes from a "reference" plan set I had for some prototype buildings and there were a lot of things hand-waved and odd that I didn't much care for (unplanned diaphragm terminations without collectors, dropped headers that weren't designed unbraced, more esoteric stuff, I think they were still calling for A36 anchor rods in 2017). And paradoxically the other stuff they had was so detailed I've never seen any other firm include them (detailed T-bracing for a gable end frame, including a cross-section and nailing called out, for example, rather than, say "2x brace, per code, by truss design engineer" or some other such nonsense [ the truss design people DON'T do these designs, and if they do, they are for Temporary bracing, there's a whole BOK on that I haven't posted).
I usually do beam on top for HSS columns. This does not produce fantastic moment capacity, looks like there's a potential for at least some prying action, but they are clean and don't involve field welding, and a 3/4" cap plate is not all that flexible compared to an HSS flange moment capacity vis-a-vis prying. Usually these kinds of portals I am using for minimal (lateral only) loads and there is some potential bracing for the column (at least) out of plane. The beam isn't very convincingly braced out of plane as they tend to go into wood construction.
I've done a few monsters for convention centers, but those are WF columns, not HSS. and I forget but I believe those were side-mounted with plates).
HSS columns are pretty lackluster at drift control as well as lacking in strength. But there are a lot of options for fitting the buggers in a 2x4 or 2x6 wall (most of mine, being northern, are 2x6, driven by energy code/insulation thickness). Let's just ignore the base plates, please.
Stiffener in the beam I would say depends largely on the downward load, when it is really minor I'm not sold that stiffener is really going to get you anything. My detail might show them, I think it does, and I also think it's mandatory (or a more detailed analysis is required to prove it can be omitted than most engineers will bother with, they either include it because they don't want to bother, or they leave it out because they don't know it's supposed to be there and they've seen too few "peer" drawings with them), but a single vertical stiffener mid-bearing and a decent cap plate would probably transfer fine in to the HSS wall for downward load. There is or was a check for that in the AISC code, it's in my "one ring" spreadsheet. I can dig it up if people really want.
(And I'm the guy who wrote that somewhat editorial FAQ on cantilever (steel) roof framing and in ALL those failures the stiffener was omitted). 1981-2009 Cantilever Roof Framing.
I know it's shorthand, but that's NOT my detail. It's just a detail I happen to have laying about and I threw it up there for discussion. (Insert Donald Rumsfeld Joke/reference here). It's the drawing I had, not the drawing I wish I had.
This comes from a "reference" plan set I had for some prototype buildings and there were a lot of things hand-waved and odd that I didn't much care for (unplanned diaphragm terminations without collectors, dropped headers that weren't designed unbraced, more esoteric stuff, I think they were still calling for A36 anchor rods in 2017). And paradoxically the other stuff they had was so detailed I've never seen any other firm include them (detailed T-bracing for a gable end frame, including a cross-section and nailing called out, for example, rather than, say "2x brace, per code, by truss design engineer" or some other such nonsense [ the truss design people DON'T do these designs, and if they do, they are for Temporary bracing, there's a whole BOK on that I haven't posted).
I usually do beam on top for HSS columns. This does not produce fantastic moment capacity, looks like there's a potential for at least some prying action, but they are clean and don't involve field welding, and a 3/4" cap plate is not all that flexible compared to an HSS flange moment capacity vis-a-vis prying. Usually these kinds of portals I am using for minimal (lateral only) loads and there is some potential bracing for the column (at least) out of plane. The beam isn't very convincingly braced out of plane as they tend to go into wood construction.
I've done a few monsters for convention centers, but those are WF columns, not HSS. and I forget but I believe those were side-mounted with plates).
HSS columns are pretty lackluster at drift control as well as lacking in strength. But there are a lot of options for fitting the buggers in a 2x4 or 2x6 wall (most of mine, being northern, are 2x6, driven by energy code/insulation thickness). Let's just ignore the base plates, please.
Stiffener in the beam I would say depends largely on the downward load, when it is really minor I'm not sold that stiffener is really going to get you anything. My detail might show them, I think it does, and I also think it's mandatory (or a more detailed analysis is required to prove it can be omitted than most engineers will bother with, they either include it because they don't want to bother, or they leave it out because they don't know it's supposed to be there and they've seen too few "peer" drawings with them), but a single vertical stiffener mid-bearing and a decent cap plate would probably transfer fine in to the HSS wall for downward load. There is or was a check for that in the AISC code, it's in my "one ring" spreadsheet. I can dig it up if people really want.
(And I'm the guy who wrote that somewhat editorial FAQ on cantilever (steel) roof framing and in ALL those failures the stiffener was omitted). 1981-2009 Cantilever Roof Framing.
TRAK.Structural
Structural
As detailed I think this connection would provide the required stiffness, but that's a lot of welding.
Flotsam7018
Structural
I generally don't specify less than a 1/4" fillet, however in a past life I was an AWS certified welder and laugh at the thought that most welders are going to dependably control the fillet leg size within 1/16". Unless you're dealing with a shop with CWI periodic inspections checking the fillets with a gauge (not typically the shop doing a residential moment frame) it's just not going to be to that level of accuracy.
Discontinued product list: HUC28 isn't there as near as I can tell.
www.strongtie.com
ssttoolbox.widen.net
That's a concealed flange hanger that's perhaps not all that necessary here. I was thinking more of a top flange hanger. But even that isn't going to work when there's no top plate to hang from.
That's a pretty -- atypical detail, and what are those circles for anyway?
Discontinued Products
A list of our discontinued products including replacement products when available, along with alternative products that may be considered for a project.
www.strongtie.com
StrongTie-Discontinued-Products.xlsx
That's a concealed flange hanger that's perhaps not all that necessary here. I was thinking more of a top flange hanger. But even that isn't going to work when there's no top plate to hang from.
That's a pretty -- atypical detail, and what are those circles for anyway?
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- #27
Bolts for the nailers.
Interesting. Yea, they have a 26 and a 210. I'll figure something out. Not mcu load there
- Thread starter
- #29
It's a 2x10. I have used wood-to-metal screws for this (on my house actually) and it worked quite well. I am cheap and wanted something easy. I think I will stick bolts for this unless you can show me a better way.
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- #31
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- #33
I don't see any such restrictions after a quick perusal of Simpson's catalog C-F-2023TECHSUPP.pdf. You can also get them galvanized (TBG). If your steel flange is greater than 1/4" thick (but less than 1/2" thick), you would have to go with the TF screw, which is not available galvanized. Seems a lot easier (and cheaper) to me than bolts. When the flange thickness is 1/2" or greater, I've used welded studs. The contractors I work with prefer welded studs to through bolts because the welding is a fairly routine procedure in a steel shop whereas a through bolt requires more work for the framer in the field.
Regarding welding a hanger vs. specifying (2)-2x8s, again, it seems easier (cheaper) to me to add the joist to avoid the field welding of the hanger for the single joist hanger. To get a single joist hanger to work, the top flange would have to be offset, which is a special order item, but I support a HUC28-2 isn't very readily available either.
On a recent job I was thinking the same thing, but the fabricator told me it would be a lot more work for them to fabricate the beams with welded studs versus bolt holes. He mentioned the holes are an automated process for them while welding studs is not. Of course, I imagine this is dependent on the fabrication shop.
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- #36
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- #38
Can they close it off with glass at some point? I was picturing a three season jobby and those all have glass, or could. Exposed to rain isn't quite the same as "wet environment" but i can understand caution or skepticism. But if you're being consistent, then all the connections get those 40 to 60 percent reductions via Cm.
Most of these have at least occasional drying, and aren't saturated. Of course make your own decision on the circumstances. PPT wood is pretty hostile to connection materials, and hangers, too.
Most of these have at least occasional drying, and aren't saturated. Of course make your own decision on the circumstances. PPT wood is pretty hostile to connection materials, and hangers, too.
- Thread starter
- #40
Certainly they could. i did not design for that additional lateral load but the plan reviewers around here a pretty good about flagging that if the time comes. They can add some bracing then. There are only so many contingencies I am willing to include in my plans.
No screened porch around here will pass a framing inspection w/o PT wood and the requisite hardware.
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