huangyhg

wind application with a fabric.
dear group,
i have what i consider an unique structural problem. it basically involves two steel rods that are attached to a wall in the hortizontal, one on top of each other (approximately 50 " apart and the rods are 37" wide. the two rods are attached at each end in a bracket that allows rotation. the steel rods are connected by a fabric. the fabric is stretch by rotating the top rod with a ratchet to tigthten fabric like a drum. i have been trying to size the rod since i need to consider all the forces on the rod. this fabric is subjected to wind and is solid.
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------------------------------- rod
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* *
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-------------------------------- rod
any help would be greatly appreciated in determining the forces and how they would be acted upon the steel rod.
thanks.

do you mean this assembly can swing like a door?
i am not sure i am doing this right. however in response to trainguy's question, the application is as protective cover and not as door. basically it acts like a blind that goes up and down. the fabric is wrapped around the rod at the top and the fabric is attached to a bottom rod. to close over the protected area, the bottom is lowered using a handle by rotating the top rod. once the bottom rod is at the bottom it is inserted into a bracket. then using a ratchet on the top rod, the fabric is tightened between the two rods to create a strong barrier.
it is hard to explain, but that is it in a nutshell.
thanks
as i understand this, you are looking for the bending moment on the rods.effectively the tightened fabric will curve out giving a force as a tangent to this curve onto the rods. there are so many variables here which would have to be considered and for the size of the problem are practically indeterminable.
if you assumed that the fabric was just a slab spanning onto beams it would give you a basic load & moment giving, say, a 1.5" tube or bar. look at the stress & deflection & take a view. problems like these are half calculation to see if you are in the right order & half judgement on top of that.

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