Retail Product

[mmmbmf]

I have been asked to design a special Christmas Tree that my client wants to package and sell nationally. The structure will be in pieces that the consumer will put together themselves and can be located indoors or outdoors. The question I have is: What wind speed would you design for? My thoughts are if I design for 150 mph, the product may be over-designed and cost prohibitive. On the other hand, I am thinking of designing for a target mph like 75 mph. The product then could be packaged with limitations of liability and directions to disassemble and take down during times of high wind expectancy. Also, I am anticipating using ASCE 7 for a guideline for loading. Your thoughts are appreciated.

 

[kylesito]

I would use ASCE 7.

I think your best approach is to check what 150 does to the design. Since it's a pretty insignificant structure and probably comes down to the single center pole, you might find that you need a certain thickness just to build and fabricate it that can actually handle the 150 mph. If not, then you might check for what your minimum size could take and make a judgement about making any changes from there. Even though the tree may "fail" in 150 mph, if it can take 100 for instance you might decide that the ramifications of "failure" are not enough to warrant increasing the design to resist 150 mph.



PE, SE
Eastern United States

"If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death!"
~Code of Hammurabi

 

[SlideRuleEra]

Since a Christmas tree is a temporary "structure", suggest that you take a look at guidelines on that application. To my knowledge there are no "codes" but much thought has gone into what a reasonable approach would be. Take a look at this article in Structure Magazine:

http://www.structuremag.org/article.aspx?articleID=833

Based on that article and similar information, a design speed of 70 MPH, or less, may be reasonable. Also, if your product is intended for use in the USA, the Christmas season is a fairly quiet time for extreme wind events with reduced risk of hurricanes and tornadoes.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[XR250]

Sounds like you would need a wind tunnel rather than ASCE-7.
What would you use for shape factors?
I am surprised they are getting an SE involved as it will likely end up being cost prohibitive when you are done with it :>

 

[XR250]

One other thing...
You may want to check with your E&O provider (if you have one)
There may be exclusions in there for retail items or items that will be built over and over again.

 

[mmmbmf]

Thank you all for your advice and opinions. I really appreciate the time you took to provide me with your productive comments. The article was also very informative.