Lesson on Wind Strength

So, when I design new elements for my display, I’m very concious about the elements and what conditions my display will be subjected to in the central Indiana area.  We have a wide variety of weather during December that could be anything such as rain, snow, sub-zero temperatures, and high-winds.

Each element is given great thought about how it will stand up to these conditions, and I personally like to make sure I over-engineer things for that margin of safety.

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Well, this year I learned a good lesson.  We had incredibly high-winds for an extended period of time on January 26th, 2014 (It had been too cold to take the display down).  During the overnight hours, the wind actually pushed back this 200 lb structure around 20 feet and then turned it sideways to the wind.  The next gusts that came through, torqued the structure by twisting it and it collapsed with a loud cracking sound.   The whole thing was caught on my surveillance video.  It’s incredible the amount of force wind can put on things.  Fortunately, this was in the side yard by itself, so no one was hurt and it didn’t damage anything else in the display.

Originally, I had designed this sign with eye-hooks on the side that allowed it to be staked to the ground to anchor it in place, so that little cross-bracing was needed.  For the last two years, my thinking was that this structure was so big and heavy, that the stakes were unnecessary.   I was wrong.  The flat screen acted like a big paddle, directing the air, and “catching” during the gusts.

I’m still deciding whether I want to rebuild it, or go in a different direction for the projector screen.

 

UPDATE: I haven’t built a new one yet.  I repaired the broken legs and put it back together for our 2014 season.

One thought on “Lesson on Wind Strength

  1. jay

    Follow-up Post: Because things will be changing with the display next year, I decided on the short-term fix of repairing the two snapped legs and reassembling for this year. Everything went back together well and I kept the remnant shorter pieces for another project. Although this will be the last year i’ll use it, it has served me well and taught me some things!

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