Concrete Shear Wall with Steel Moment Frame on Top

[enigma2]

I am working on a 26’-0 high, single story, religious facility where the main (gravity) load-bearing construction is heavy timber, with glulam columns and beams with a flexible metal roof deck. The shell of the building consists of storefront glazing spanning between site cast or precast panels that are 18’-0 high, 12’-0 wide and located 20’-0 on center. There are clerestory windows on top of the concrete panels that continue up to the roof deck. To be able to transfer the lateral forces from the roof deck to the foundation, I was thinking about building an 8’-0 high +/- moment frame at each panel out of tube steel, with its base at the top of the concrete panels and the top beam connected to the roof deck. I am hoping this frame could be hidden in the mullion space. This structure is in a SDC A, and wind loading controls. Does this seem like a viable means of transferring the lateral load to the foundation? I’ve never had the opportunity to do a mixed system like this before, using material with such different rigidities. Can anyone lead me to a reference or an example so I can feel comfortable that I’m approaching this design properly.

Thanks.

 

[DaveAtkins]

What you are proposing sounds feasible, but you should contact the precast concrete wall supplier right away to see if it is OK. They will need to design for the loads imposed by your moment frames.

DaveAtkins

 

[enigma2]

I am revisiting this again, because the owner and architect have made some changes. The shear walls will be wet cast, so I will be the one designing the walls for the load imposed by the moment frames. The new twist is that instead of metal roof deck, laminated T&G timber decking will be used. This means that I need to transfer the diaphragm load going into the wood roof into the tube steel of the moment frame. Any advice on how to make a connection between the wood deck and the hot-rolled steel to properly transfer the loads from the wood deck to the frame?

 

[whyun]

Connect a top countersunk wood nailer (thick enough to receive the deck nails) with threaded studs welded to the TS member (at intervals designed to transfer the diaphragm shear).