Allowable Wind Speed

[KaBone]

I'm working on chain link fence post footings and the wind load it must support. I go to the wind tables and get the ultimate wind speed. I look at the equation to calculate the depth and it uses the allowable lateral soil-bearing pressure (IBC 2018, Eq 18-1). It also uses the applied lateral force from the wind.
Since the equation is based on allowable soil pressure, are you folks using the applied lateral force be based on the allowable wind speed (IBC 2018, 1609.3.1)?

 

[driftLimiter]

If your using ASCE 7-10 or above, the Ultimate Windspeed is used to determine 'W' for load combinations indicated in chapter 2. If you want the allowable load you simply use Section 2.4 (ASCE7-16) Load Combinations for Allowable Stress Design.

However there is a wind speed conversion equation indicated in the IBC (2018) Section 1609.3.1. But this should only be used when specifically indicated by reference standards. If you say apply equation 1609.3.1 to an ultimate wind speed then the Load Combination factor you would use for ASD is 1.0W not 0.7W.

 

[thejonster]

Check if the fence is low enough that it is 'exempt' from permitting per IBC 105
[URL unfurl="true"]https://up.codes/viewer/alabama/ibc-2021/chapter/1/scope-and-administration#105.2[/url]
"Fences not over 7 feet (2134 mm) high"