ASCE 7 Cantilever Column Structural System

[DesignIntegrity]

To whom it may concern:

In ASCE 7 under structural systems there is a section entitled Cantlever Column. Three sub-systems are listed:

1. Steel SMRF
2. Steel OMRF
3. Concrete SMRF

In the UBC '97, Table 16-N Structural Systems the only compariable system listed is Cantilevered column element.

My understanding of cantilever systems is that the base of a column is fixed and the top is pinned. Lateral resistance is provided by the stiffness of the fixed cantilever. The system has a lower R value to compensate for the lack of a more conventional elastic system.

Can someone assist me in understanding why the SMRF and OMRF systems are listed if indeed the tops of the cantilever columns are pinned to the horizontal framing (no moment connections required)?

Can I find a reference for the system requirements posted somewhere?

Thank you for your assistance with this matter.

Regards

DesignIntegrity

 

[JAE]

The moment resisting element is the base of the cantilever, where its moment is transferred to whatever is supporting it. And the supporting element is not always just a footing - a penthouse on top of a building could be a cantilever system where the columns are moment-connected to the supporting steel frame.