How to brace Raised platform on turntable without visible bracing?

Fusrohdave

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Jun 11, 2019
Location
New Jersey
I’m building a set for She Loves Me. The designer is more or less copying the broadway production. The middle unit is on a turntable. It has two levels, the first has a door and a spiral staircase, the second is an enclosed office. I have it mostly together but the thing is wobbly as hell. I’m trying to hide any bracing but since both sides are visible I’m struggling. I’ll attach images but if anyone has ideas or tips to really solidify the second level I would appreciate it.

The 2x4 posts in the images are temporary until my round posts come in, and Both sides of the unit are very open and visible.
 

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josh88

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Steel. You can cross brace within any closed off walls but for something like that best answer is really that it should be steel framed to provide the rigidity and added strength, OR compromise and know that for it to be safely braced, something has to be visible or reworked.
 

Fusrohdave

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Jun 11, 2019
Location
New Jersey
Steel. You can cross brace within any closed off walls but for something like that best answer is really that it should be steel framed to provide the rigidity and added strength, OR compromise and know that for it to be safely braced, something has to be visible or reworked.
Replace the 2x4 stud with with steel? Or just the posts?
 

josh88

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Replace the 2x4 stud with with steel? Or just the posts?
No I'd frame the whole thing with steel tube frame if you could, any of the structure supporting that top platform. Welded right angles/angle braces are going to be a lot stronger corners than wood and will have less flex from the supports as well. With those walls(especially once they are skinned), side to side bracing shouldn't be much of an issue, its the front to back thats going to keep giving you the most problem. What are the round posts you're waiting for made of?
 

Colin

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Jan 23, 2015
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Eastern Massachusetts
Okay, covering the walls will help considerably then - both sides better than one. I'm not saying that'll necessarily be enough, but I'd expect it to be a drastic improvement, particularly if that curved wall gets rigidly tied into the rest, and particularly if you re-do all the top plates of the stud walls to be continuous pieces (laminated plywood sweep for the curved one) that bear on top of the studs. The continuous piece helps rigidity, especially in the curved wall which is presently your only chance at bracing perpendicular to the flat wall. Not thrilled to ever see a platform shearing fasteners (and what are those fasteners?) but if it's already done that way you could just add blocking below those joints (doesn't solve the wiggle inherent in multi-part top/bottom plates though).

Can you build diagonals into this by adding a taller facing around the platform edge, fastening to legs such that the platform looks thicker, but still the clean lines you want (no diagonals visible)? Looks like you have some head room?

Diameter of those posts could help too - what size?
 

Fusrohdave

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Jun 11, 2019
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New Jersey
No I'd frame the whole thing with steel tube frame if you could, any of the structure supporting that top platform. Welded right angles/angle braces are going to be a lot stronger corners than wood and will have less flex from the supports as well. With those walls(especially once they are skinned), side to side bracing shouldn't be much of an issue, its the front to back thats going to keep giving you the most problem. What are the round posts you're waiting for made of?
I was afraid you’d say that. I don’t have the capability of working with metal unfortunately.
The posts are a steel pole covered in vinyl, but they attach with bolts. I was considering removing the above platform, stress skinning and then adding mounting plates to each corner to reduce movements at the joints, including the floor. Possibly also adding “y” bracing to the top corners of the stud wall, although that runs the risk of getting in the actors way when walking under the “balcony”
 

Fusrohdave

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Jun 11, 2019
Location
New Jersey
Do you think the movement is coming from the flexibility of the 2x4 posts (and the screws they’re attached with) or at the stud wall? I’m wondering if the steel posts will be enough to keep it from moving much
 

Fusrohdave

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Joined
Jun 11, 2019
Location
New Jersey
Okay, covering the walls will help considerably then - both sides better than one. I'm not saying that'll necessarily be enough, but I'd expect it to be a drastic improvement, particularly if that curved wall gets rigidly tied into the rest, and particularly if you re-do all the top plates of the stud walls to be continuous pieces (laminated plywood sweep for the curved one) that bear on top of the studs. The continuous piece helps rigidity, especially in the curved wall which is presently your only chance at bracing perpendicular to the flat wall. Not thrilled to ever see a platform shearing fasteners (and what are those fasteners?) but if it's already done that way you could just add blocking below those joints (doesn't solve the wiggle inherent in multi-part top/bottom plates though).

Can you build diagonals into this by adding a taller facing around the platform edge, fastening to legs such that the platform looks thicker, but still the clean lines you want (no diagonals visible)? Looks like you have some head room?

Diameter of those posts could help too - what size?
So no platform will go above the curved wall. Instead that wall will continue upward to the second level. So there will be a sort of balcony on either side of the stud wall

I see your point with the continuous header on the stud wall. Can’t believe I didn’t catch that myself. Yes that will be replaced with a straight run and I’ll add an improved header to the curved wall as well.

the posts that are coming in are 4” round steel wrapped in vinyl That connect via bolts.

im having trouble picturing the diagonals you’re talking about. Could you elaborate more?
 

Colin

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Jan 23, 2015
Location
Eastern Massachusetts
So no platform will go above the curved wall. Instead that wall will continue upward to the second level. So there will be a sort of balcony on either side of the stud wall

I see your point with the continuous header on the stud wall. Can’t believe I didn’t catch that myself. Yes that will be replaced with a straight run and I’ll add an improved header to the curved wall as well.

the posts that are coming in are 4” round steel wrapped in vinyl That connect via bolts.

im having trouble picturing the diagonals you’re talking about. Could you elaborate more?
As pictured. Add a skirt around the platform, fastened to platform frame and walls/legs. Facing = diagonal bracing. A real sheathing - 1/2 or 3/4 ply - would be the best thing. Corners could be braced behind it too if needed.

The curved wall can help whether or not it has a platform on top. If it is rigidly connected to the flat wall then the depth of the curve acts as a diagonal. It all has to be as rigid as can be though - home construction, not set construction.
 

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BillConnerFASTC

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Jan 30, 2010
Location
Clayton NY 13624
Agree on top curved plate. I assume that the vertical framing is all on top of the platform, not through deck and attached to platform frame? That moment connection would have helped. Hard covering of walls - probably as thin as 1/4 ply both sides or 1/2 one side will help in the one direction. Anyway to get a diagonal or a wall perpendicular to the wall with door? That seems to be the weak axis. An "X" or Collin's "skirt" - a rigid diaphragm - up high would help a lot.

A diagonal from top of wall to bottom of post that could be moved one side to other if possible as part of turning?
 

Fusrohdave

Member
Joined
Jun 11, 2019
Location
New Jersey
As pictured. Add a skirt around the platform, fastened to platform frame and walls/legs. Facing = diagonal bracing. A real sheathing - 1/2 or 3/4 ply - would be the best thing. Corners could be braced behind it too if needed.

The curved wall can help whether or not it has a platform on top. If it is rigidly connected to the flat wall then the depth of the curve acts as a diagonal. It all has to be as rigid as can be though - home construction, not set construction.
Ahh, gotcha. That makes sense. I believe this, along with the other edits, will be the way I will go. Thank you very much for your help