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Re: Spreadsheet Tutorial - developing Flow charts to write Nested Conditional "IF" Functions

[Subject Prev][Subject Next][Thread Prev][Thread Next] Dennis:

We appreciate your effort to provide an elementary sign pole analysis and to present some methods for developing a spreadsheet.  There are a number of us on the list that design poles for various clients.  Following are some suggestions for inclusion in your spreadsheet.
1.      The wind speed (qs) should be for any velocity.  If the local wind speed is 85 mph or 155 mph, the template should be able to calculate this.
2.      The supporting pole itself has to be considered.   Shielding by the sign is not allowed.  The Cq for the pole is 1.4 x 2/3rds per note 8 of Table 16-H.
3.      The input for the various signs is not as clear as it could be on the spreadsheet.  A more organized tabular section would be helpful, with a check box for flat and circular sections.
4.      The Ce factor (not Cs) should actually interpolate a more accurate value. 
5.      Consider the possibility of a communication dish(s) also being placed on the sign structure.  (Good rental income for the owner).  This could be part of the tabular input.
6.      In the tabular section, the weight of each element should be included. 
7.      Identify which code is being used.  My above comments are considering the 1997 UBC, but there are some differences in the 2000 IBC.  Also, some people may be designing  the structure using the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminares and Traffic Signals or for British Standards.
8.      Probably easiest is to have a separate page in the spreadsheet for each of these codes rather that a selection of which code being used on one page. 
9.      The final numerical result should be a total wind force (Vwind) and the height of the ground (Centroid of effort) to use in the design of the footing or pier.  Note that the moment for the analysis of the footing will be taken about bottom of the footing or the design moment for the pier will be taken somewhere below the ground level, depending on whose lateral pier analysis you use and where the passive soil starts. A separate page for a spread footing or pier should be considered with the results from the sign pole(s) analysis linked to these pages.
10.     For actual arithmetic, a more presentable result for the lateral wind force would not carry the calculation out to two decimal places.  This is a pet peeve of mine; but the lesser numbers make the appearance of a neater calculation page.  In fact, I prefer to do as much of the presentation of the calculations in kips, inch-kips or foot-kips where it is appropriate..  Smaller and simpler numbers.
11.     Reference Example Problem 10 - Wind Design of Pole-supported Sign and Foundation of the Wind Commentary to the UBC, obtainable form the Structural Engineers Association of Washington.
12.     I know of at least three other consultants on this list who have spreadsheets written and have been used for a number of years which include all of the comments above as well as other enhancements.  The wind portion for mine was written around 1989 and the pole section, if I remember correctly, was written in 1995.  Unfortunately for me, these are in Lotus123 and I am now in the process of converting all of our Lotus templates to Excel.

Neil Moore, S.E.
neil moore and associates
shingle springs, california