Formula to compare the strength of pipe versus C channel

In summary, the conversation discusses comparing pipe and channel as lateral supports for building systems. The speaker has just received a patent for a system using steel channels and pipe posts for walls, fences, and buildings. They believe their system is simpler, easier to build, and stronger than the current method using old chain link fence brackets and framework. The use of C channel or purlin is discussed as a way to provide vertical support for expanded metal, which does not require vertical support. The speaker is seeking a comparison of the advantages of using their system with C channel versus the use of pipe in chain link fence framework. They mention stiffness and strength as factors to consider, but also mention the complication of comparing multiple items in the system. Wind load is also
  • #1
wroughtn_harv
1
0
What I'm trying to do is compare pipe to channel as far as lateral strength.

I have just received a patent, 7,707,794. It's for a building system of walls, fences, and buildings using steel channels and pipe posts.

The current way to build a high security fence using expanded metal panels depends upon old chain link fence brackets and framework. I believe my system provides not only a simpler and easier to build framework, it's stronger.

Here's my logic. Pipe is strong three hundred and sixty degrees. That is a good thing when building a framework for chain link fence. Chain link is a woven fabric and needs to be supported not only laterally but vertically so pipe works best.

Expanded metal on the other hand doesn't require vertical support. In fact it can provide vertical support for the framework, a sheet of expanded metal is stronger than it's parent shape as a sheet.

My system uses C channel or purlin oriented horizontally. I get the benefits of the purlin or channel's greatest strength where its needed the most for expanded metal support.

What I need is a comparison reflecting that advantage over the use of pipe in chain link fence framework. 2" X 4" fourteen gauge channel versus 1 1/4 schedule forty pipe.

I'm attaching some photos to give you an idea what I'm talking about.

I appreciate any help possible. I can make things but then I need help explaining it, darn.
 

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  • #2
What type of strength are you talking about here? In engineering it can mean a fair number of things. Are you talking about stiffness (resistance to bending?), elastic limit (how much to bend it so that it stays bent) or yield strength (total load before it will fail)?

I'm not a civil engineer, but I believe you want to look at a beam model for whatever material the fence is made of. With a beam model you can essentially explain the force required to bend various cross-sections (Eg, why we use I beams so often). Take a look at this Wikipedia article: http://en.wikipedia.org/wiki/Euler–Bernoulli_beam_equation
 
  • #3
Harv, Interesting system. A 4" x 2" 14 ga C will be much stiffer and stronger than a 1 1/4" sch 40 pipe. For stiffness compare the moment of inertia (I in in^4), for strength compare the section modulus (S in in^3). The pipe is easy google section properties of schedule 40 pipe.

But as Hologram mentions it's hard to quantify, your expananded metal grating may pick up more wind load than a standard chain link because the air can't pass through as easily. In a way you are simultaneously comparing 4 items, the pipe, c, exp mtl, and chain link, that complicates it.

You would need to be more specific about the loading (wind load) usually you'd start with a wind speed, mph, and calculate the load in psf, and that would be different for the porosity of the screen (% open).

Hope that helps. S
 

1. What is the formula for comparing the strength of pipe versus C channel?

The formula for comparing the strength of pipe versus C channel is the moment of inertia divided by the section modulus. This can be represented as:

Strength of Pipe / Strength of C channel = Moment of Inertia / Section Modulus

2. How do you calculate the moment of inertia for pipe and C channel?

The moment of inertia for pipe can be calculated using the formula:

I = (π/64) x (D^4 - d^4), where D is the outer diameter and d is the inner diameter.

The moment of inertia for C channel can be calculated using the formula:

I = (bw^3)/12 + (h^3b)/24, where b is the base width and h is the height of the channel.

3. What is the significance of the section modulus in this comparison?

The section modulus is a measure of the resistance of a cross-sectional shape to bending. It takes into account the shape, size, and distribution of the material in the cross-section, and is an important factor in determining the strength of a structural element.

4. Can the strength of pipe and C channel be compared using other methods?

Yes, there are other methods for comparing the strength of pipe and C channel, such as the yield strength, tensile strength, and compressive strength. However, using the moment of inertia and section modulus is a common and effective way to compare the two structural elements.

5. Are there any limitations to using this formula for comparison?

While the formula for comparing the strength of pipe versus C channel is a useful tool for initial analysis, it does not take into account factors such as material properties, manufacturing processes, and loading conditions. These should also be considered when determining the actual strength of a structural element.

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