Steel moment frame on second story of SFR 2

[RusMax]

Hi everyone!

I’m new to this website but while Googling various subjects, have found information on this website extremely helpful. So, I wanted to sincerely thank folks who take the time to reply.

I have a single family residence that is two stories on the front of the house and three stories in the back. The client wants to open up a wall on the second story in the back more. This is an exterior wall.

Has anyone had experience in putting in steel moment frames in this situation, where there is going to be a wood shear wall above and below the steel moment frame?

Thank you, in advance for any help!

 

[phamENG]

I designed one the other day...don't like it at all, but it is doable. (Fortunately for me everyone got scared when they saw my design and the owner made the architect change their design.) I settled on a solution where all of the fixity is in the beam to column joint in the steel. Assume your base is pinned. Of course using the shallowest column section you can get away with will help make that assumption a reality.

 

[KootK]

Yuck. I'd sooner plug in some simpson strong walls etc if there's space available. Considerations:

1) Kind of a seismic nightmare in terms of the irregularities etc. You'd have to eat the penalties for that and use the lowest system R-value for everything.

2) Any third story shear wall hold downs landing on the moment frame would need to be connected to the moment frame beam to transfer those loads. And that load path would increase the drift in the third story shear wall.

3) Any shear in the moment frame columns would need to get transferred into the first floor shear wall system at the column bases. It can be tricky to deliver heavy concentrated shear loads into light frame wood systems. Obviously, a few screws into rim board isn't going to get it done.

4) The axial forces in your moment frame columns would need to be transferred through the first floor and down to the foundation. I suspect that would require some pretty invasive detailing in an existing structure.

5) Your moment frame needs P-delta analysis for the two levels of gravity load that it will stabilize laterally. But, then, that's just ordinary moment frame design I suppose.