Notional Loads AISC 360-05 Appendix 7 Direct Analysis Method 1

[VillegasST]

Colleagues:

I am wondering if notional loads should be separated for live and dead loads for load combinations. In addition, should notional loads use corresponding load factor? or a unity load factor shall be used for notional loads?

Finally, in a dual system, for example peripherical concrete walls with intermediate steel columns and steel beams, should the concrete weight be included to estimate total notional loads?

Thanks for your help.

 

[JoshPlumSE]

Regarding the Load Level for Notional Loads:
Notional loads are applied as a percentage of the design loads. So, if you are using factored load combination (i.e. 1.2DL + 1.6LL) the notional load can already be considered to be factored.

If you're using service level loads (1.0DL + 1.0LL) then the Notional load remains unfactored. Though the analysis is required to be carried out at 1.6*actual load levels.

Regarding Concrete Weight:
Yes, concrete weight should be included in the calculation of notional loads.

Regarding keeping DL and LL separate:
If you did this, you could apply a different notional load for the 1.2DL +1.6LL case than you apply for the 1.4LL case. So, it's not unreasonable. However, in practice most folks will just look at their worst case gravity load combination and use that for their notional loads. Adjusting it for each load combination is just more effort than it is usually worth.