Moment frames in two directions 2

[IceNine]

Does anyone have any advice on using steel moment frames (IMFs) in two directions for a building in Seismic Design Category D? Specifically, is it even possible to use prequalified connections in each direction at the same joint?

 

[prsconsultant]

Odiehall:

AISC / SAC has limited database for weak-axis moment connections. Here is an excerpt from FEMA-350. In summary, moment connections in both axis of a column can be designed but there are no pre-qualified connections. All connections have to be tested.

3.3.3.3 Connections to Column Minor Axis:

Connections to the minor axis of a column should be qualified by testing following the procedures of Section 3.9. If minor-axis connections are to be used in conjunction with major-axis connections at the same column, the testing program should include biaxial bending effects at the connection.

Commentary: In general, the prequalified connections have not been tested for use with columns oriented so that beams connect to the minor axis of the column. Two tests of Reduced Beam Section connections in this orientation were conducted, which indicated good performance. These tests were conducted to provide a general indication of the possible performance of weak axis connections, but are not considered to comprise a sufficient database for prequalification of such connections.

 

[Taro]

Some the proprietary connections (Sideplate, etc.) have been tested for weak axis configurations.

 

[SteelMomentFrame]

Adding to Taro's comment. SidePlate has a SMF connection (SureFrame 2) that qualifies for dual strong axis applications using cruciform columns under AISC 341-02 Appendix P & S with no additional testing as certified by ICCES ER 1275. The SureFrame2 has been used in high-seismic SMF applications including California State University San Bernardino , Magic Technologies in Milpitas, CA (San Francisco Bay area), and Salt Lake Regional Hospital Medical Office Building.

SureFrame 2 can be used in corner, T, and full dual strong axis configurations.

 

[Taro]

The newly released AISC 358-05 "Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications" now contains prequalified connections using cruciform columns.