3x3 square tubing vs 4x2 square tubing

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In summary: The vertical tubing will be welded on a 3x2 11gauge square tubing. I'm trying to attach a word or paint document to show a quick visual but its too big of a file. The horizontal 20" tubing will be made of a 1" 1/4thick round tubing slipped inside a 1.75x1.75" 12 gauge tubing then another piece of square tubing will form a triangular shape kinda like this:In summary, the stronger structure is the 3x3 .25 inch thick square tubing.
  • #1
camaroz2808
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Which is stronger 3x3 .25 inch thick square tubing or 4x2 .125 inch thick square tubing?

When positioned vertically about 40inches high (considering that when positioned vertically it is completely secured), and a 20 inch square tubing attached at different levels between the 40 inches (either 3x3 or 4x2 tubing), at any levels of the 40 inch tube can it handle at least 1000lbs? (specially at the top)

In other word: Forming like an upside down "L" shape being 40 inches vertically (with either 3x3 0.25thick or 4x2 0.125thick square tubing) and 20 inches horizontally (considering that this part is strong enough). Will this be strong enough to hand at least 1000lbs?

OR should I angle the L shape instead of being 90 degrees possibly 95 degrees. At maximum I wouldn't want the angle to be more than 100.12 degrees. But overall I would prefer to not add any angle at all.

I was looking at this link for some help but I think I need more help.
https://www.physicsforums.com/showthread.php?t=351727

If none of them will handle it please add suggestions.

Please let me know if any of this is unclear.
 
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  • #2
Kind of confusing. Assuming that the upside L is anchored into the ground, I think the breaking point would be caused by bending stress in the vertical column caused by the 1000 lb force at the end of the 20 inch span (you said to assume the 20 inch span can support the weight?).

If my above assumption is correct then I would say the 3x3 .25" thick square is stronger than the 4x2 .125" rectangle. I calculated the bending stress in the 40" beam to be as follows:


4x2 .125"
S = My/I
S = (1000 lb * (20"+2")*2"*12 / (2"(4")^3 - 1.75"(3.75")^3)
S = 14,784 psi

3x3 .25"
S = My/I
S = (1000 lb * (20" + 1.5")*1.5"*12 / (3"(3")^3 - 2.5"(2.5")^3)
S = 9,228 psi

Above assumes 4x2 and 3x3 to be outer dimensions. Whether or not it can support the weight depends on the material of course. If the 20 inch beam is heavy you have to add that into the calculation as well. Limiting factor could also be how the 20" beam and the 40" beam are connected to each other. If they are bolted together I could see the bolts failing from sheer.

The above was a rough calculation. More info is needed about the situation to accurately say whether or not the structure would collapse.
 
  • #3
Thanks for the reply. The vertical tubing will be welded on a 3x2 11gauge square tubing. I'm trying to attach a word or paint document to show a quick visual but its too big of a file. The horizontal 20" tubing will be made of a 1" 1/4thick round tubing slipped inside a 1.75x1.75" 12 gauge tubing then another piece of square tubing will form a triangular shape kinda like this:

20"
__ ________________________________
I I I_____________________________I
I I I /
I I I /
About 9" apart I I I /
I I I /
I I I /
I I I /
I I I /
_ I I/
I I
I I
I I
I I
I I
_________________ I I______________________________
I_________________________________________________I

It has similar design as a half powerlifting rack like this one with low bracing of the vertical tubing (Btw for my design purposes I don't want it to be higher than 10" off the ground or 8" from the 2x3 base tubing):
http://www.powertecfitness.com/uploads/wb-hr10/buy.jpg [Broken]
combines with this one:
http://cardiff-sportsgear.co.uk/shop/images/press squat stand.jpg
But I want mine to hold more weight, that is why I am using much thicker steel, and if I am not mistaken. 1/4 thick steel is almost twice as thick as what they use.
OMG I just realized that I didn't say that there are two of them btw like a powerlifting rack lol. Please let me know you opinions or if my explanations are unclear.

Thanks
 
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1. What is the difference between 3x3 square tubing and 4x2 square tubing?

The main difference between 3x3 and 4x2 square tubing is their dimensions. The numbers represent the width and height of the tubing in inches. Therefore, 3x3 square tubing has equal sides of 3 inches, while 4x2 square tubing has sides of 4 inches and 2 inches. This results in a difference in overall size and weight of the tubing.

2. Which one is stronger, 3x3 or 4x2 square tubing?

The strength of square tubing depends on various factors such as the type of material, wall thickness, and design. In general, 4x2 square tubing may be slightly stronger than 3x3 square tubing because it has a larger surface area and can withstand more weight. However, the difference in strength may be minimal and can vary depending on the specific use and application.

3. Is 3x3 or 4x2 square tubing better for structural support?

Both 3x3 and 4x2 square tubing can be used for structural support, but the choice ultimately depends on the specific project and the amount of weight that needs to be supported. As mentioned before, 4x2 square tubing may have a slight advantage in strength due to its larger surface area, but it may also be heavier and more expensive. It is important to consult an engineer or use load-bearing calculations to determine the appropriate size for structural support.

4. What are the common uses for 3x3 and 4x2 square tubing?

Square tubing is commonly used in construction, manufacturing, and various industrial applications. The strength and durability of the tubing make it suitable for structural support, framing, and creating sturdy frameworks for machinery and equipment. 3x3 and 4x2 square tubing are also used in the automotive industry for roll cages and chassis reinforcement.

5. Can 3x3 and 4x2 square tubing be used interchangeably?

3x3 and 4x2 square tubing may have similar properties and uses, but they are not interchangeable. The difference in dimensions and strength can affect the overall performance and safety of the structure. It is important to choose the appropriate size and type of tubing for the specific application to ensure optimal results.

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