Questions on ASD Wind Loads in ASCE 7-16 & 7-22

[VinnyAZ]

I am trying to covert wind speeds to ASD using the newer codes. I have a few questions:

1) One can convert wind speeds from the wind maps using the equation sqrt(0.6)*V or Table 1609.3.1 in IBC. However a 0.6 wind factor is already applied to the ASD load combinations (D+0.6W). Do I covert the wind loads first to ASD (for say deflection checks), but then also apply the 0.6 load combination when checking stress?

2) Do I have to convert the concurrent wind (with ice) loads in Table 10.5-1 to ASD?

 

[WinelandV]

The load combinations in ASCE7-16 and 7-22 (and 7-10) are set up for wind speeds at the ultimate level. If you're going to use an equivalent ASD wind speed, then you would use the load combinations as found in 7-05 (last year for calculating wind at service level).

Let me be more specific - since the 7-10, having adjusted the wind speeds to the ultimate level, also adjust the load combinations (and associated load factors) to account for the different wind speed. Which is why in LRFD combos, wind has a LF = 1.0 (in 7-05, the LRFD LF for wind was 1.6).

As for ice, it is my understanding that the wind speeds on ice were already ultimate wind speeds - evidenced by the 1.0 LF for Ice Wind in the 7-05 LRFD ice equations.

 

[phamENG]

Do I covert the wind loads first to ASD (for say deflection checks), but then also apply the 0.6 load combination when checking stress?

No! The sqrt(0.6)xV is worthless for nearly everything. The IBC gives some specific cases where it must be used - flagpoles and one or two other standards that were never updated to modern wind design standards. That, and if you're using a product that was designed under the older codes (3s gust, 50 year MRI - doesn't work for fastest mile wind speeds, that's a whole other conversion). So if a garage door was certified for 110mph winds using ASCE 7-05, you'd be able to use it in winds up to 142mph under ASCE 7-10 and later codes (110mph/sqrt(0.6)=142mph).

Don't know about ice. Not really a design consideration on most structures where I practice.