Hollow Core Plank to Shear Wall Connection

[AustinStructural]

I am designing a 3 story project that utilizes Hollow Core Plank for the floor and roof system and light gauge steel stud walls for the bearing system. The lateral system is to be comprised of sheet steel shear walls.

I have no issue with the connection of the shear walls floor-to-floor, and the diaphragm to wall connection where the plank is bearing (span perpendicular to) on the walls. However, I am just not sure how to make the connection between all of the elements where the plank is non bearing (span parallel to) on the walls. If my floor was flat, then I would just tie the diaphragm in to the plates with shot pins, however, with estimated cambers up to 1.25" I just am not sure how to make this connection work economically.

I am trying to stay away from proprietary lateral systems here, so my intent is to make this work with standard SSMA sections.

Can anyone provide advice/details on how they have made this connection in the past and felt comfortable with?

Thank you

 

[msquared48]

Light gage studs to support hollow core plank? The holloow core alone is around 60 to 90 psf depending on the size and type, let alone the live load. This does not seem to be a very good idea to me - capacity concerns here depending on the span, let alone the connections you are asking about. The normal support is concrete or masonry. Light gage studs...??? I would steer clear of that.

Mike McCann
MMC Engineering

 

[hokie66]

You will need a light gauge angle each side of the wall, shot fixed to the slab. If it is a shear wall, you should provide vertical slots in the vertical leg, fasteners to allow the floor deflection while taking the horizontal shear.

I do agree with Mike that the system is unusual, but as long as the "light gauge" stud walls are not too light, i.e. designed properly, it would work.

 

[haynewp]

http://www.nitterhouse.com/DrawingS...Fs/Hollow Core/pg18SHPlankConn_NonBrgStud.pdf

 

[AustinStructural]

Thank you Mike and Hokie for your responses. Although the plank is heavy, the wall studs at the first floor essentially are the same that you would have with a 9 story cold formed floor system with level rock. The gauge of the studs at the first floor typically come in around 68 mils or (2) 54 mils, depending on the flange size and stud spacing. This seems to be a popular method of construction on the east coast based on reading I have done, so I am willing to give it a try.

Thanks. AS.

 

[BAretired]

I was amazed to learn a few years ago that one of the typical systems in Winnipeg, Manitoba for walk-up apartments was precast hollow core slabs supported on wood stud walls. It does not appeal to me, but I guess if wood studs will do it, why not steel studs?

BA

 

[lkjh345]

Yes, this system has been used before. I have seen articles in various magazines on it.

FWIW, my 2 cents: I would beg, borrow or steal a set of plans from a project that has used this system. To correctly work out all the required design and details of an unfamiliar system, from scratch, just seems like a very difficult thing to do and get it all right the first time.

Call steel stud suppliers and see if they have plan sets and/or standard details they are willing to share.

JMHO

 

[haynewp]

You have to get the shear out of the plank and into the wall of course. I suggest a steel tube with headed studs along the top of the bearing stud wall.

 

[WpgKarl]

BAretired - Hollowcore slabs were used on wood bearing walls in Winnipeg, but not without problems. You will typically find that a multi storey hollowcore bldg on wood walls will load the walls enough to crush the horizontal wall plates in bearing (lots of guys used to wood forget to check this). Secondly, the creep and shrinkage of the horizontal wood plates will actually make things worse, and drywall (sheetrock) will start taking load and crush / crack.

Since then, if they use a wood wall to support hollowcore, they use a steel stud track plate on the top and bottom and pick the thickest gauge you can still nail thru. In this case you have to make sure the hollowcore can support the load when a stud is right under a void. Wood never made a whole lot of sense to me for fire reasons (see picture)

Lastly, connecting the hollowcore diaphragm into light gauge steel studs (or wood) seems challenging as you ususally have very small bearing lengths and if you try to shoot something into the edge of a slab, it can pop off.

 

[BAretired]

WpgKarl,

Interesting. It just doesn't seem like a sensible combination of materials.

BA

 

[jike]

If you were a firefighter, how would you like to fight a fire in this type of structure?

 

[BadgerEngineer]

This type of system is being used more and more. I'm seeing it on quite a few 3-5 story hotel projects. TSN has a product often used with hollow core called the sigma stud.

Download the construction guide at the below link. It shows some of the connection and camber issues you might have to address when using hollow core with light gage.

http://www.steelnetwork.com/SigmaStud.aspx?link_id=9

 

[AustinStructural]

When I said I was trying to stay away from proprietary systems I was discretely stating that I didn't want to use the StiffWall system by TSN. Sigma stud is not necessary for bearing on a 2-3 story project as there is typically no cost savings here.

I think I will try to connect a light gauge angle to the underside of the deck and the top track of the shear wall. Also, I figure these "non-bearing" shear walls should just be stick framed so the studs can be cut to the lengths required for the as built camber of the plank.

Thanks again for all your help. If ANYONE else reads this that has experience with these systems, please feel free to post anything.

Thanks. AS.

 

[haynewp]

Why not just use a deflection slip track?

 

[UcfSE]

I think using angles to transfer shear is good, but try to think of a way that allows for some adjustment so that the walls studs parallel to the plank don't have to be cut to different lengths because of the camber.

I really recommend you contact one or two local precasters and get their opinion. Many are willing to help out, and no one knows their system better than they do.