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rock.freak667

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## Homework Statement

http://img571.imageshack.us/img571/2026/framekq.jpg [Broken]

I need some help with finding the forces associated with this structure. I drew it badly from how a friend described it.

A point load would be placed on it so, a weight W would be at the centre + the weight of the metal at that point + another point load to simulate a person standing on the structure near the edge.

I am to assume that the entire frame is made out of iron, and the legs are welded onto to the rectangular top and it is resting on the ground. The distance from the ground to the rectangular top should be 15 feet. It will also be subjected to a wind load as well.

I'd like to know how to perform an analysis that will show me the best angle to have the legs at and if the structure can withstand the forces.

## Homework Equations

∑F

_{x}=∑F

_{y}=∑F

_{z}=∑M=0

σ

_{b}=My/I

## The Attempt at a Solution

Weight of point load = W

Weight of person = w

Weight of material = m

_{n}g

I can get the properties of the metal and whatnot, I'd just like some help in starting the analysis.

Mostly the reactions at the joints is where I get confused, normally I'd think the ones where the legs are joined to the top plate are the same, but that would get confusing when I consider the reactions due to the ground.

EDIT:

Summing vertical forces: W+w-4m

_{1}g+m

_{2}g= 4R+4N

(R= reaction due by the joints and N= reactions at the ground)

Now this is assuming all the joint reactions are equal and all of the ground reactions are equal.

Now if I take moments about the load W, all of my reactions will cancel out. This means that what I am doing is wrong.

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