Equivalent or notional horizontal force??

[Bubik]

Hi everyone

Please help. Does anybody know what the difference is between 'notional horizontal force' (related to second order effect I guess) and 'Equivalent horizontal force' ( I think related to frame imperfection) I have always thought they are the same things. It is very frustrated not to know (and confusing).

Thanks

 

[theshearstud]

I believe they are the same thing. AISC uses the term "notional load". Eurocode uses the term "Equivalent Horizontal Force".

 

[theshearstud]

Both used to account for imperfections only

 

[BAretired]

I find the concept of notional loads a bit confusing too. A notional load as defined by CISC is a fictitious lateral load that allows the stability of the frame with failure modes involving in-plane bending to be computed based on the actual length (K = 1) for beam-columns.

The following suggests a method of calculating notional loads:

http://msc.aisc.org/globalassets/modern-steel/archives/2011/01/2011v01_how-too_approach.pdf

BA

 

[Bubik]

Thanks for your answers

However in portal frame analysis notional (sensitivity to second order effect) and horizontal( Initial frame imperfection) forces are considered separately.. so how come are they the same????
I refer to Eurocode particularly.