Cold-formed steel column platform framing detail 1

[milkshakelake]

Anyone have a detail for how to connect a cold-formed steel beam (like a box beam) to a cold-formed steel column within a stud wall? I'd like to do this with platform framing, i.e. not a continuous column.

I've shown the detail I've been working out below. It's in progress so it's missing some annotations. I think it works, but there are so many angles and stiffeners. I'm afraid it would be difficult to construct. 8 angles and 2 stiffeners per beam/column connection, which is 60 to 80 screws. I think someone will kill me.

 

[YC611]

See below the details I typically use. The angle thickness and # of screws changes depending on the actual loading.

 

[milkshakelake]

See below the details I typically use. The angle thickness and # of screws changes depending on the actual loading.

View attachment 1322

Thanks for sending! You have a lot fewer angles than me, so I'm slightly hesitant if this assembly is stable. But it's good to know that it's possible. I think I can cut down on some of my connections at least.

 

[YC611]

Thanks for sending! You have a lot fewer angles than me, so I'm slightly hesitant if this assembly is stable. But it's good to know that it's possible. I think I can cut down on some of my connections at least.

My pleasure to give back to this community.

I see a total of 8 angles by the side of the boxed beam that are trying to secure the beam at its location with column and concrete slab on metal decking. Is there a reason why you do that? To create some kind of fixed connection?

 

[milkshakelake]

It's not to create a fixed connection.

1. Top of column should be connected to top track, so that's 2 (you used 1).

2. Beam should be well connected to top track. (4 so far)

3. Probably will eliminate this one, but beam should also be connected to deck. (Still 4 so far, since I might remove this due to diaphragm screws.)

4. Bottom of column should be connected to deck. (6 total)

I am thinking that I can cut this by half. Like putting an angle on one side instead of two. Let's say the column has 40 kips load. Taking 2% of that for stability = 800 lb, which one angle and 3 screws on each leg should support.

Thanks for giving back to the community! This community has helped me a lot so I try to do that too. I'm very grateful to everyone here.

 

[YC611]

It's not to create a fixed connection.

1. Top of column should be connected to top track, so that's 2 (you used 1).

2. Beam should be well connected to top track. (4 so far)

3. Probably will eliminate this one, but beam should also be connected to deck. (Still 4 so far, since I might remove this due to diaphragm screws.)

4. Bottom of column should be connected to deck. (6 total)

I am thinking that I can cut this by half. Like putting an angle on one side instead of two. Let's say the column has 40 kips load. Taking 2% of that for stability = 800 lb, which one angle and 3 screws on each leg should support.

Thanks for giving back to the community! This community has helped me a lot so I try to do that too. I'm very grateful to everyone here.

For #1, the top of columns and top track should already be connected by screws on front and back sides as shown on your sketch. The 1 angle I showed was to connect beam to column.

For #2, I agree with you, I will reconsider this on my design, but for most of my projects, I do not see a that big of loads on my girder as I mainly used them under partition walls and occasionally to support some bearing walls, but still won't reach 40 kips at columns.

For #3, I also count on the diaphragm screws to do the work.

For #4, I kind of disagree. I view the built-up posts same as the stud. The connection to the bottom track with screws seem sufficient to me.

Also, I am all for positive connection and I'd love to add all those angles on the details, but GC is going to kill me with them.

 

[milkshakelake]

Got it. I think we're almost on the same page, and I agree with you. For #4, only thing I'm wondering is if the bottom track can handle a stability load. My gut tells me that it should be okay if I did an FyZx kind of calculation with the track leg in bending.


I think it might work; I'll need to ponder it for a while though.

Sometimes, the post loads can get to 30 kips because they are carrying beams on every floor. Kind of like stair beams. I think 40-50 kips is also possible, though I don't remember if I've ever used that or I just went with steel HSS columns. I'm just using it as a conservative upper bound to calculate the incidental lateral load.

 

[YC611]

Got it. I think we're almost on the same page, and I agree with you. For #4, only thing I'm wondering is if the bottom track can handle a stability load. My gut tells me that it should be okay if I did an FyZx kind of calculation with the track leg in bending.

View attachment 1332
I think it might work; I'll need to ponder it for a while though.

Sometimes, the post loads can get to 30 kips because they are carrying beams on every floor. Kind of like stair beams. I think 40-50 kips is also possible, though I don't remember if I've ever used that or I just went with steel HSS columns. I'm just using it as a conservative upper bound to calculate the incidental lateral load.

Got it. I think we're almost on the same page, and I agree with you. For #4, only thing I'm wondering is if the bottom track can handle a stability load. My gut tells me that it should be okay if I did an FyZx kind of calculation with the track leg in bending.

View attachment 1332
I think it might work; I'll need to ponder it for a while though.

Sometimes, the post loads can get to 30 kips because they are carrying beams on every floor. Kind of like stair beams. I think 40-50 kips is also possible, though I don't remember if I've ever used that or I just went with steel HSS columns. I'm just using it as a conservative upper bound to calculate the incidental lateral load.

That’s very fair. Though I probably won’t see this kind of load in my projects. Most of the lowest floor stud in my project is at 6-7 kips and built-up post by stair at 15-16 kips.