aci 318 limit of deflection and snow load 2

[ramihabchi]

hi.I want to design a slab that supports columns subject to snow load.table 9.5(b) of ACI give permissible limites for deflection.is snow load considered as live load or it is not included in deflection check?

 

[BAretired]

Snow load is a live load in the sense that it is not there all of the time. It is not a live load when live load reduction factors are applied, because it can be present for a considerable duration, and is not diminished by increasing area covered. Snow load is included in deflection check and for that purpose, it is considered live load.

BA

 

[ChorasDen]

To add to what BA said, design snow load is what we use for deflection and strength analysis. Design snow load is different than what we expect to see from a 5 or 10 year storm, and is a statistically based approach to attempt to properly envelop a more significant design storm to allow us to check the structural performance of the supporting members. This design snow load is a temporary load, and thus, should be treated as a live load.

I agree that snow load isn't reducible per live load reduction equations in chapter 16 of IBC. However, it may be reducible per wind shadow and exposure effects, but these may also increase localized snow load. Best to look at chapter 7 of ASCE 7 for more information.