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Wind loading

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Once again I would reference ASCE Transactions, Vol. 126, Part II, pages 1124 
- 1198, with particular attention to Table 4 (d) on pages 1160 and 1161 which 
describes the situation that you have --- an open structure (shelter) with 
and without an obstruction (train or stored material).  These coefficients 
were developed in wind tunnel tests for the Swiss building code and AITC 
included the table in the 1st Edition of the Timber Construction Manual.

Absent using the ASCE coefficients cited in the last paragraph, I would 
consider the structure partially enclosed IAW UBC.  I definitely would not 
consider it an "open structure" and do not consider *any* building other than 
a bunker as a closed building.  Before using ASCE 7 with any confidence, I 
would use ANSI A58.1-1972 which gives a more realistic idea of wind forces on 
structures than the watered down versions of subsequent A58.1 versions, ASCE 
7's and UBC's.

Hope this helps.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Gabe Bohm wrote:

>>Consider a solid wall, with perpendicular wind. ASCE 7 tells us how to
calculate wind pressures. So far, so good.

Now, let's place an open structure 10 feet in front of the wall, parallel to
the wall. The open structure consists of columns, beams & braces and has
ties to the wall. The wind is still perpendicular. How do you calculate wind
loads on both wall and open structure? ASCE 7 does not address this

Let's further complicate things by placing vessels, platforms, and piping in
the 10 foot space between the open structure and the wall. 

What is the best method to assess the wind loading on open structure,
equipment and wall without being overly conservative? How do you account for
shielding? Are there any published articles that address this situation?
Your thoughts will be much appreciated.


Gabe Bohm
San Dimas, California<<