Detail Advice

[haynewp]

I have kind of weird situation where there is a 2 story building with a composite steel floor system with wood shear walls at the perimeter. The wood walls around the perimeter are not load bearing, and some are designated as shear walls and some are so perforated with openings that they are just there to frame the windows and doors. But they will need a similar connection without the necessary shear transfer.

I got stuck half way through this detail today. I need to allow the steel beam to deflect vertically without loading the studs or the plywood that is below. At the same time, I need to transfer the shear from the upper shear wall (roof to second floor) through the floor beam, and into the lower shear wall.

I really don't like the detail I started because of the cost. There is an angle that is welded to the bottom of the WF beam supported the studs out of plane and allowing the floor to deflect independently of the shear wall studs and sheathing below. But this is very expensive. Any suggestions on a better way to make it work? I couldn't find a Simpson connector that would allow for the deflection. (see attached file)

 

[msquared48]

2.5" seems like a lot to me for a composite floor deflection. Are you sure about this figure?

Mike McCann
McCann Engineering

 

[msquared48]

Also, you should only have to allow for the live load deflection, cambering for the dead load. Is the 2.5" all live load?

Mike McCann
McCann Engineering

 

[haynewp]

That number has not been finalized. The total deflection is about 2.1", I will camber the DL out and the live load deflection will be about 1.6" for a 48 ft long beam. My gap will be reduced to 2" or less before I am done.

thanks

 

[haynewp]

Actually, I need to tighten that up more. With the stone the live load deflection should be less than L/600. I can add some columns to cut down the span also, it is very early in the project.

 

[msquared48]

I cannot quickly think of a better detail as I have done similar in the past in log home and PT concrete construction.

However, you might want to consider using a 3X or 4X top plate in the shear wall to avoid splitting when installing the lags. You also need to specify the length of the lags and call for predrilling.

Mike McCann
McCann Engineering

 

[JAE]

I'd agree with Mike above - a larger top plate (double or triple) or even turning the top plate into multiple 2x header-type members -say 3 - 2x6's on end with plywood spacers to match the stud depth, to give you some meat to attach the lags to would be good. That way your lags don't screw into an interface joint between multiple top plates.

 

[haynewp]

OK, so it appears my line of thought is not way off. I feel like I am spending so much money money on supporting the wood wall at the top, you could switch to steel bracing with metal stud infill and a slip track and it not cost much more. We don't do a lot of wood design so I questioned I am using the most economical method.

BTW
This uploading files feature is really nice.

 

[haynewp]

Mike,

I intended a 3x as you can see the difference in scale between the top plate and the bottom plate at the second floor, I have it labeled incorrectly. Or maybe I will use multiple plates per JAE.

Will note pre-drilling also.

 

[msquared48]

I would use a double top plate system, with the top plate being a 3X min for the lags.

Mike McCann
McCann Engineering

 

[msquared48]

If you get the deflection down to say 1" or less, you should be able to use a 2X nailer attached to the bottom flange of the W shape with 1/2" Nelson Sill Plate anchors, and Simpson DTC clips nailed to this plate and the double top plate system of the wall below. With this arrangement, you should be able to use a double 2X top plate for the shear wall below instead of the 3X or 4X.

Also, I would consider L/1000 for the masonry.

Good luck.

Mike McCann
McCann Engineering

 

[haynewp]

thx for all comments

 

[HouseBoy]

Is there a definative issue wiht the edge distance of the screw into the 3x or 4x ?
There will be some eccentricity with the angle on the "inside" of the top plate and the plywood on the outside. Is that an issue?
I realize the question is about the bottom angle (and you said it's early in the process) but...
Since this is a shearwall, is there no opportunity to place a column somewhere to cut down on the deflection of the 48 ft. span?
The 3/8 thick shelf angle (on top of steel beam) is only supported by a 1/4 inch bent plate.
Are there uclosure/building envelope issues with that portion of the brick immediately in front of the steel? It seems that is not vaper barrier etc. until you get down to the studs.

 

[haynewp]

I have already revised a lot of this. Like I said, I was half done with it and was just looking for direction on the wood support issue before I finished the detail. thanks