analysis of exterior CMU elevator tower 1

[SQUIDALE]

Hello-

I am designing a cmu elevator rower to be added to the exterior of an existing masonry building as a "bump-out". The elevator shaft is basically a hollow masonry tube, extending three floors up. Wind, seismic and elevator rail loads parallel to the existing wall that I am bumping out on will tend to rack the shaft walls, in plan. Trying to use the exterior walls of the new shaft as shear walls for their full 3-story height to resist these lateral loads doesn't seem feasible because of the very high aspect ratio (height/length). Have thought instead to resolve lateral loads at each floor level into a couple that is to be resisted by connection to the existing floor diaphragms.

Have seen many other buildings with exterior elev shafts but this is my first time doing this. Has this approach been done before?

 

[epr]

SQUIDALE,
Yes it has been done before, probably many times. The main thing you have to consider is differential settlement. Use mechanical connections from the new masonry walls to the existing walls that provide lateral attachment, but vertical slippage. Also, sill details at each floor level must be able to accommodate some vertical differential.

 

[SQUIDALE]

Epr- Thanks for your comments. Will be careful about tying in the walls that allows for some increment of vertical differential movement. This will probably also help another concern I have which is shrinkage in the new block. Thanks.

 

[3dboy]

Uh, you should not have any problem to get a 3 story cmu elevator shaft to support itself. I just did a 4 story one and got it to work.