Tall Party Wall At Stair/Elevator Opening

[StructureMaster]

First off thanks to everyone who contributes to this forum, it has helped me get starting points for design many times. Please excuse me if this topic has been addressed in other threads, I wasn't able to find one directly addressing this topic.

I am working on a residential duplex which is three stories. Each level is 14' floor to floor. The ridge at the party wall line is 20 ft above the upper level floor. It is a truss framed roof and truss floor system for the upper 2 levels. The roof trusses bear on the party walls for each unit. The floor trusses run parallel to the party wall. I am using the party wall as both a shear wall for lateral loads and bearing wall for gravity loads.

The issue is there are stair openings, roughly 16 ft long, and elevator shafts about 6ft on each side of the party wall. This gives about 22 ft of party wall which is not tied to the floor sytems and there for not braced perpendicular to the wall. Obviously I can not have 48 ft tall studs from foundation to roof. How would you guys handle breaking up the studs?

I was planning on running a steel beam at each floor level in the party wall along this opening with steel columns on each end. The idea being the steel beam would act as a collector for the lateral load at each floor diaphragm and transfer it to the party wall below. I would design it as a compression member and insure it would not buckle perpendicular to the wall. However I am worried about creating a hing by breaking the studs at each level. Since there aren't lateral loads perpendicular to the wall is this an issue? Any other concerns with this method? Are there better options? Thanks in advance for any info!

 

[jayrod12]

Does your elevator not have walls on all 4 sides that you can use to brace it?

Then I have used LVL wind beams as plates (for the entire 16ft span without splices) to allow the wall to be framed as two separate walls.

 

[StructureMaster]

I do have 4 elevator walls so that is a great point. Even using LVL wind beam at plates I was concerned about creating a hing at the break in the studs. I guess if I design it for torsion as well as perpendicular bending/buckling I can mitigate that. Thanks!

 

[jayrod12]

No torsion. The studs on either side of the plates will negate that. I don't see a situation where the lower studs are loaded with wind and the upper studs are not.