Type 2 (Wind Only) Moment Frame 8

[RFreund]

I have a couple of questions regarding wind only moment frames. Meaning when analyzing gravity loads the beams in the frame are pin-pin. However when analyzing lateral loads the connection is fixed.

1. Is my description correct in describing the design process.
2. Are these typical?
3. Can you provide me a reference that discuses the design of these frames.

I just have a hard "stomaching" this design philosophy but it seems like many frames in the past have been designed this way.

Any other insight is appreciated.

EIT

 

[cap4000]

Another pdf.

http://www.modernsteel.com/Uploads/Issues/September_2005/30745_flexible.pdf

 

[peal724]

Lion, you quoted the 14th Edition with this

"As an alternative, flexible moment connections (FMC) may be used as a simplified approach to PR moment connection design, particularly for preliminary design."

My 13th Edition says the exact same thing except it does not contain the last four words "particularly for preliminary design." I'm curious why AISC would add that phrase.

I think the concern about joint rotation is taken care of by the prescriptive geometry and welding locations shown in AISC's FMC sketches. As long as you follow their "weld here" and "don't weld here" guidance, then you'll be ok.

 

[peal724]

Remember, the structure will behave as you have designed it. Designing structures is you shaping how it will act, not you being subjected to it's actions.

 

[hokie66]

peal724,

Would that it were so! We do our best, but the structure is frequently smarter than we are.