# Steel "C" channel strength



## captfl2x (Aug 25, 2016)

I hope someone can answer this or direct me to an answer. What is the vertical strength of a steel "C" channel with outside dimensions of 3" x 1" x 3/16" x 36". At 18", I will be putting a 5/8" hole thru the center of the channel and I am concerned how much it will be weakened. I've probably just asked a simple question that requires a complicated answer, but any help will be appreciated.


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## Bondo (Dec 8, 2007)

Ayuh,.... What are ya wantin' to support with this 3' chunk of 3"x 3/16" channel iron, 'n how will it be attached to whatever this is,..??

Is it mill run hot rolled channel iron, or a flat stock, bent into a C channel,..??
This is hot rolled channel iron,....


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## captfl2x (Aug 25, 2016)

The channel is hot rolled and it is the span between two supporting members on a trailer.


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## Bondo (Dec 8, 2007)

captfl2x said:


> The channel is hot rolled and it is the span between two supporting members on a trailer.


Ayuh,.... How long is the span, 'n how heavy will it be loaded,..??


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## captfl2x (Aug 25, 2016)

The C channels are the structural members on each side of the trailer and are in a vertical position. The length of the C channel where the hole will be is 36" without other support/reinforcement. The hole will be centered ion this 36" length. I will assume that the trailer will carry it's max load capacity of 3,000 lbs. The trailer load area is 5' W x 10' L. Of the 3,000 lbs, 300 # will be on the hitch. Assume the remainder of the load will be spread evenly throughout the load area. If that is the case, that is 54#s /sq. ft. or .375 # / sq inch.

The 36" length of unsupported C channel rail across the trailer would have 810 # on it (3'x5'x54#) or 405# per side C channel. Since the C channel has a leg of 1"W x 36" L, the weight would be distributed evenly at 11.25# per linear inch. There's probably is a flaw somewhere in my thought process or calculations, but maybe this will help. 

Maybe a 5/8' hole in the center of the c channel would be negligible strength reduction but I can also only calculate a static load.


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## Bondo (Dec 8, 2007)

Ayuh,.... You could step up to 3"x 1" x *1/4"*,. 'n go for it,....

it's pretty stiff stuff,....
I wouldn't sweat a 5/8" hole,.... incidental,...


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## captfl2x (Aug 25, 2016)

Thanks. The trailer is already built so I can't change to a 1/4". I just need to drill the two holes (one each side).


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## Bondo (Dec 8, 2007)

Knowin' what yer tryin' to do would help,...


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## captfl2x (Aug 25, 2016)

Since I'm not a "spring chicken" anymore, I need help raising and lowering the drive-on tailgate. I believe that a lift will be needed only on one side but the other side should have a latch device. This trailer is a flat bed with no upper side rails to use.


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## Bondo (Dec 8, 2007)

Ok,... but that doesn't explain how ya wanta use the channel iron,....

I suggest ya rig up something like This,....


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## captfl2x (Aug 25, 2016)

I've looked at that lifter assist before and if I had body rails I definitely would use it. There are several variations of that. Who ever was first didn't tie down the patent firm enough. Without body rails, I would use the holes thru the C channel as anchor points for my lifter. Early stages of planning. My first thought was to determine if the holes thru the C channels would be an issue. Appreciated your help.


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## Bondo (Dec 8, 2007)

> My first thought *was to determine if the holes thru the C channels would be an issue*.


Nope,... Not enough to matter one bit,....


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## MI-Roger (Aug 8, 2009)

Will the hole be in the center of the 3-inch leg or the 1-inch leg? If the 3-inch leg then Bondo is absolutely correct. Placing a hole dead-center will put it on the neutral axis of the channel as you have installed it, and the neutral axis carries zero stress/strain.


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## captfl2x (Aug 25, 2016)

The hole will be in the center of the 3" leg. Thanks for the info.


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