Strong column weak beam - SCWB

[FOX89]

Hello Folks,

For the SMF seismic design requirements, the strong column weak beam approach is required at the connection zone per AISC 341 and 358 which makes me under impression that it is not required for the full length of column to be stronger but only the portion at the connection zone, am i getting it right ? and if so, what extent above and below the connection shall be under this requirement. I have navigated in FEMA but couldn't find any clear requirement.

 

[KootK]

For the SMF seismic design requirements, the strong column weak beam approach is required at the connection zone per AISC 341 and 358 which makes me under impression that it is not required for the full length of column to be stronger but only the portion at the connection zone, am i getting it right ?

Not exactly right. For the spirit of SCWB to remain in tact, plastic hinges must be prevented from forming anywhere along the columns (other than roof level columns in some cases). Column lateral moments typically are at a maximum at the ends and diminish towards mid-height. You could, conceivably, allow your column strength to drop off in the same proportion while still preventing plastic hinges anywhere along their length.

 

[FOX89]

Sure kootk, since the moment diminishes toward the mid-height, plastic hinges will not happed at this location, but only at the maximum moment zone. So can i scale the column moment diagram by Mp(beam)/Mu(beam), reinforce the column till reaching the zone where these moments are equal. Refer to the below diagram.