huangyhg

aluminum tubing strength
i am wanting to manufacture a prototype aluminum ladder. a ladder we currently manufacture uses 1.750 x .750 x .125 6005 t5 channel. i would like to use a 1.750 x .750 x ? 6005 t5 rectangular tube. my question is, what wall thickness can i use on the tubing that would match the strength of the .0625 wall thickness of the channel? thank you very much in advance for any replies.

try the "aluminum design manual" from
i am sorry that should have read "the same strength as the .125 wall thickness of the channel"
strength is a relative term. if you are just wanting similar area and moment of inertia in the strong direction, both 0.064" and 0.080" will do. there may be other factors you need to consider however such as weld size, method of attachment, local crippling. contact me if you need some help with the overall design.
zcp
thank you for the replies. the application is a ladder rail which hangs down at a 25 degree angle, held by a stop block and the ladder frame at that angle. the ladder rail itself is 47.25" with the fulcrum being 2.875" from one end.
first - your initial post has the channel .125 thick but then .065 thick. which is it?
second - if you change from a channel to a tube keeping the width, depth and thickness the same, then the tube will be stronger.
third - if you halve the thickness but double the quantity, the strength will in theory be the same. you will have to review the thinner sections for web cripling, shear and local buckling.
fourth - for a small item as this, go with the same thickness but a tube. the couple of dollars won't really matter unless you are making a lot of them. welding the rungs will be easier in thicker material. when human life or safety is at risk, don't even think of skimping.
you should also consult the appropriate osha guidelines for minimum load and size requirements for ladder components. i think it is 1920.27.
thank you all very much! the channel i use now is .125 thick, i want to start using a tube in its place and knew i wouldnt have to have it as thick but just wasnt sure how to figure what i could cut thickness to. i do have concerns about going to .0625 thickness on tube but feel sure that .080-.090 would be more than sufficient. as it stands now the boat ladder will hold 560 pounds with no problem using the .125 channel. excuse my rambling, i appreciate you folks taking the time to help me.

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