An engineering question...

[journey11]

Here's my new tractor/coop...



Still got a couple of aesthetic elements to add to it, but it is up and running. It weighs around 300 lbs. Here's my concern... DH says that it would blow over in high winds if broadsided (we live on a ridgeline and often get 50-70 mph gusts in a bad storm.) My opinion is that the A-frame distributes the weight out in the base and it should stand fine.

What's your opinion or experience with this? Would I need to batten down the hatches or no?

 

[HEChicken]

Nice job on the tractor! Since I am not an engineer but my DH is, I asked him to look at the picture and information and told him your concern. He said "I'll go with the husband".

Sorry...

 

[journey11]

Oh, you know how men gotta stick together. LOL Thanks for checking.

 

[jetdog]

A 2x4 on the ground near the jack extending out on each side will stable it up and not affect moving it around.

 

[Bear Foot Farm]

I really doubt it weighs anywhere near 300 lbs, and it WILL blow over in a strong enough wind, since it's topheavy
I'd stake it to the ground with some rebar

 

[ChickensAreSweet]

That coop will definitely blow over in a strong wind!!! No question.

 

[4 the Birds]

The angle of the coop will help disperse wind load compared to a vertical surface but I doubt that the weight of the coop would overcome strong wind pressures for such a large surface area. We have had metal deck chairs blow across the yard in high winds! Easy enough to add eye bolts and stake it down but the suggestion of a long horizontal 2x4 may be a good one so that you don't have to pull stubborn stakes out of the ground often. Have to agree with DH.

 

[Arielle]

A 2x4 on the ground near the jack extending out on each side will stable it up and not affect moving it around.

I was thinking along these lines too. Allows for a cinder block to be placed onto the extension too, when you know a bigger storm is blowing in.

THe broad sides act like a kite. Maybe decrease the height of the plywood next time-- nice design though.

 

[Ridgerunner]

Journey, if we were over on the Gardening forum I’d probably tease you about that crack on men sticking together, but since we’re over here I’ll behave, at least a bit.

I’m an engineer. If I had some dimensions it would be pretty easy to give an estimate of what wind speed it would take to knock that over. What I’d need is how long that broadside is, the height above ground the bottom of that solid plywood is, the height above ground the top of that solid plywood is, and how wide the base of that A-frame is.

For example, assume that is a 4’x8’ sheet of plywood with bottom 2’ off the ground and the top 6’. I know it’s on a slope so those numbers are not exact but I’m trying to make the math easy. A 70 mph wind would put a force around 700 pounds of force on that plywood, acting 4 feet off the ground. That gives you an overturning moment of about 2800 foot-pounds.

Resisting that overturning moment, assuming it does weigh 300 pounds and that the base is 4’ wide, you have about 600 foot-pounds of resistance to overturning.

You wanted an engineering solution. It’s rough numbers with a lot of simplification, but in a 70 mph wind, that thing is spinning like a top.

 

[Arielle]

Journey, if we were over on the Gardening forum I’d probably tease you about that crack on men sticking together, but since we’re over here I’ll behave, at least a bit.

I’m an engineer. If I had some dimensions it would be pretty easy to give an estimate of what wind speed it would take to knock that over. What I’d need is how long that broadside is, the height above ground the bottom of that solid plywood is, the height above ground the top of that solid plywood is, and how wide the base of that A-frame is.

For example, assume that is a 4’x8’ sheet of plywood with bottom 2’ off the ground and the top 6’. I know it’s on a slope so those numbers are not exact but I’m trying to make the math easy. A 70 mph wind would put a force around 700 pounds of force on that plywood, acting 4 feet off the ground. That gives you an overturning moment of about 2800 foot-pounds.

Resisting that overturning moment, assuming it does weigh 300 pounds and that the base is 4’ wide, you have about 600 foot-pounds of resistance to overturning.

You wanted an engineering solution. It’s rough numbers with a lot of simplification, but in a 70 mph wind, that thing is spinning like a top.

Is that 600 lb of resistance vs. 700 or vs 2800 ???

Can the coop be turned into the wind, the triangle end, to decrease some of the pressure?