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RE: wind lines and jurisdictions

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My thought was directed at the structural engineer trying to be too precise in picking a wind zone to determine application of environmental loads.
-----Original Message-----
From: Paul Feather [mailto:pfeather(--nospam--at)]
Sent: Friday, August 12, 2005 12:57 PM
To: seaint(--nospam--at)
Subject: Re: wind lines and jurisdictions

Actually I have a correction, it is 90 mph on one side and 100 mph on the other.  My previous post indicated 80 mph by mistake.
I don't think it is all that silly, and I can see where the need existed to have some form of demarcation line.  If you have been in Denver there is distinctly different wind influences due to the Rocky Mountains.
I would estimate they set the demarcation line well past the point where it is actually required, and didn't try to precisely set the line with the expected transition zone.  In this way they are conservative to a large degree, but then are not penalizing all the construction that is beyond the influence zone.  Using a major geographic element as a demarcation line makes more sense than trying to cut across neighborhoods like a zip code.
In a lot of ways it is no different than the arbitrary 1/4 mile coastal influence line for wind calculations.
----- Original Message -----
Sent: Friday, August 12, 2005 12:20 PM
Subject: RE: wind lines and jurisdictions

It seems a little silly for a structural engineer to demark a wind zone that precisely given the uncertainties in other loads, material quality, construction quality, and end user abuse.
-----Original Message-----
From: Paul Feather [mailto:pfeather(--nospam--at)]
Sent: Friday, August 12, 2005 11:10 AM
To: seaint(--nospam--at)
Subject: Re: wind lines and jurisdictions

I don't remember this language specifically.  Whenever this has occurred in the past the local building authority will usually dictate which level is required.  In Denver, for instance, they picked a particular main street and arbitrarily made this the demarcation line between wind zones.  If you are on one side of the street it is 80mph, the other is 100 mph.  You always have to draw the line somewhere....
----- Original Message -----
Sent: Friday, August 12, 2005 9:54 AM
Subject: wind lines and jurisdictions

Does anyone have a recollection of a statement in the ASCE 7-98 Standard, Commentary, or perhaps in the ASCE 7-98 version of Kishor's Guide that goes something like the following...

"when a wind speed line passes through a local jurisdiction, the line can be moved to the edge of the jurisdiction due to the fact that the lines are established by consensus of the ASCE 7 Task Committee and are not intended to be so precise as to require interpolation within the jurisdiction."

I only have the 7-02 versions of the ASCE 7 Standard/Commentary/Guide and I can't find this language in the newer documents.


Thanks in advance.


Christopher Banbury, PE


Ark Engineering, Incorporated

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