Steel shaft for elevator

[mats12]

All steel elements of the shaft are welded.
Shaft (columns) are anchored to existing building (into the middle of 200 mm thick RC slabs).
Do you think (based on your experience) that there is a need for additional bracing between columns? Weight of shaft + cabin wont have large mass/weight so earthquake forces wont be large. BTW Id calculate lateral forces when cabin is at the top of the shaft. Is that OK? Structure is inside so there is no wind.

Id model my shaft like this:
- columns base as pinned supports,
- connection between C sections and columns as pinned,
- connection between HOP columns and HOP beams as moment connections.

Places of anchoring are marked (red circles).

 

[mats12]

Any thoughts? I would really like to hear some other opinion on this.

 

[hokie66]

What does the steel frame accomplish? If your are tying the steel to a concrete structure, why does the concrete not suffice as a shaft?

What type elevator? Doesn't look like either top or bottom supported, so is it actually supported on rails off that framing?