Ordinary Moment Frame analysis - what loads to apply?

[ampersand]

I am designing a wood-frame two-story residence, and I need to design an OMF for shear along one exterior wall. When analyzing the frame and sizing the columns and beam, do I use the 'regular' load combinations- with E/1.4 as the seismic force? Or, because this is an ordinary moment frame, do I use the 'extra' load combinations, with E factored up by omega.

This obviously will make a big difference on the size of members, so any help would be appreciated.

 

[frv]

A wood moment frame?

 

[ampersand]

No, this will be a steel OMF- the rest of the project will be a wood-framed addition with wood shearwalls, etc...

 

[JoshPlumSE]

Some thoughts of the top of my head (though I have not looked up the actual code provisions):

1) Personally, I would design the column for an axial force based on the omega overstrength. I would also design the connection considering the omega overstrength. But, the beam would not be designed for the overstrength combinations. This is a personal design preference which, I believe, goes above and beyond the actual code provisions.

2) What R value would you be using? If you use R = 3.0 then I do not believe you are required to follow the seismic detailing provisions at all.

3) For OMF I do not believe there is any requirement to use the overstrength factors for the connection design. At least not in the absence of a structural irregularity.

 

[sandman21]

OMF connection design is required to comply with AISC 341 section 11.2a. Which requires the use of the required flexural strength 1.1RyMp LRFD