# Re: 10 Year Wind Conversion

• To: seaint(--nospam--at)seaint.org
• Subject: Re: 10 Year Wind Conversion
• From: h.d.richardson(--nospam--at)home.com
• Date: Thu, 08 Mar 2001 15:03:53 -0700
```Greg,

Technically, there is no direct conversion.  These values are
statistically calculated from measured data at various weather stations
near the site in question.  If you divide one by the other for several
locations you may come up with an approximate constant which could be
useful for estimating purposes.

Regards,

H. D. Richardson

Effland, Greg wrote:
>
> Typically the (assumed) conversion from 50 year wind loads to 10 year wind
>
> i.e.  Wind Pressure (10 yr) = 0.75 x Wind Pressure (50 yr)
>
> <== note these are pressures and not velocities ==>
>
> You didn't really mention usage, but 10-yr winds are typically used for
> serviceability criteria (deflection/sidesway) and 50-yr winds are used for
> stress/strength design criteria.
>
> Greg Effland, P.E.
>
> -----Original Message-----
> From: richard lewis [mailto:rlewistx(--nospam--at)juno.com]
> Sent: Thursday, March 08, 2001 3:35 PM
> To: seaint(--nospam--at)seaint.org
> Subject: 10 Year Wind Conversion
>
> I am looking for the conversion factor of changing the 50 year wind load
> to the 10 year wind load.  ASCE 7-95 has a conversion factor in the
> Commentary for their wind loads.  My problem is I am using ASCE 7-93
> which is a different wind load.  My wind speed is 80 MPH (fastest mile).
> ASCE 7-95 is based on 3 sec. gust.  Can anybody give me the conversion
> factor of 50 year wind to 10 year wind using fastest mile criteria?
>
> Rich
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