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Help with basic statics question (preventing cargo container house from blowing away in hurricane)


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Hello,

I am attempting a very basic statics question, and some of the resulting numbers seem wrong. I wonder if someone can help?  You might help keep my new house from blowing away! 

This is a simple model of a section of a cargo container withstanding a hurricane wind load (simplified as 13.4 KN at a centroid 1.45 M from the base). The weight of the container over these two footings is 20 KN. 

The goal is to determine the horizontal and vertical forces on the footers (points A and B), A_y, A_x, B_y, B_x.

I attached a picture of the FBD and moment calculations.

B_y=17.97 N.m makes sense, but A_y=2 KN doesn't.

I'm not sure how to calculate A_x and B_x.

I know this is extremely basic, but would be grateful if someone could help.

(see image)

 yZgXlZ1.jpg

 

 

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This is a classic problem, one that entraps most beginners. Because it is a 2D problem, there are only three equations of motion possible. In spite of this, you say you want to determine 4 variables: Ax, Ay, Bx, and By. It cannot be done; this problem is statically indeterminate.

You can determine the sum Ax+Bx, but you cannot determine either one separately. If you think your value for Ay is unreasonable, check your equations and your arithmetic.

DrD

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