Stair Tower Design

[ronstruc]

What chapter of ASCE 7-05 does a self-supporting stair tower fall under? Chapter 12 or 15? The stair tower is an exterior industrial type, adjacent to a building and constructed out of steel. The stair tower is approx. 70 ft. high, 18 ft. long and 10 ft. wide with landings about 8' apart. It is located in a high seismic area, and will be cross-braced (concentric braced frames). If the design falls under chapter 12 than I believe that the bracing must conform to SCBF requirements. If it is chapter 15 that governs it may only need to meet OCBF requirements. Any thoughts of whether it needs to meet SCBF or OCBF?

 

[Grizzman]

If it is a means of egress from the building, I'd have to go with chapter 12.
If it's just a way to access a roof for periodic maintenance, chapter 15.

 

[msquared48]

If it is structurally connected to the building via the landings, chapter 12.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[ronstruc]

The stair tower is self-supporting and not connected to the building for lateral and vertical support.