How to read bar grating tables - Eng-Tips

I am looking to specify bar grating that can resist AAHSTO HL-93 loading. At the very least, the 16 kips concentrated wheel load (assuming 2 pairs of wheels on the rear axle for a total of 4 wheels).

I found this supplier, but am having trouble understanding the language they're using to specify what loads to use:

[link chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/ ]Link[/url]

At the bottom left, it says either Uniform Load - lbs per sf, or Concentrated Load - lbs. per square foot of width at midspan.

Not sure which one to use, and how to interpret this. I would assume my load would be 16 kips/(2*10"x20") = 5.75 ksf

Is that my Concentrated Load? Or do I try to calculate the C load...not sure how to interpret the C load.

Thanks for your time. The HL-93 16 kip wheel load is applied to a contact area that is 10" long and 20" wide. Assuming the direction of travel of the wheel across the grate is not defined, or not limited, I think you would apply the 16 kips across 10" of grate perpendicular to the span of the main bars in the grate, divide the 16 kips by the number of bars within the 10", and then spread the load on one bar along the bar as a uniform load that is 20" wide. That will give you a fairly conservative estimate of the moment on the bar.

That would be the hard way, and probably very conservative, because it doesn't account for any distribution of load to other bars in the grate. I couldn't get your link to work, but I would be very surprised if you contacted the supplier, and they were not able to tell you the max span for their grates would be subjected to HL-93 loading.




Rod Smith, P.E., The artist formerly known as HotRod10

Does anyone have a dimensionally/weight accurate material or an iPart/iAssembly for bar grating that they would be willing to share? I have a user that is currently working on a big job that is requiring the use of lots of bar grating sections to be laid and we need something accurate so we can calculate weight.

For more information, please visit our website.

Create a material with density to reflect weight of grate as per volume.

Name the material with grate spec/name.

Create solid with that material.

If you model every grate in the structure, it'll slow down the computer.

We have used @Frederick_Law's method.  It works very well.

Sichili supply professional and honest service.

There is a small issue in drawings.  If you apply a bar grating texture to the parts, you will get a nice shaded view that behaves as expected.  If you use in-shaded views, you will see a simple outline of the part, and won't be able to see through it.

You will have to balance out the speed in the assembly and drawing environments of using solid parts with the visual fidelity of your non-shaded drawing views. 

Steve Walton
Did you find this post helpful? Feel free to Like this post.
Did your question get successfully answered? Then click on the ACCEPT SOLUTION button.

Inventor
Vault Professional

@Frederick_Law @swalton This will work accept I am unable to get the numbers to come out right. The particular bar grating we are using is 7.4 pounds per square foot. If I model up a square foot of this material the weight is coming out to 7.344. The volume of a square foot of this particular bar grating is 216 cubic inches. Since the material editor accepts the density as pounds per cubic inch I should be able to take 7.4 divided by 216 and get 0. pounds per cubic inch but the material editor is rounding to 0.034 pounds per cubic inch.

How do I get the weight to come out correctly?

Correct, I modeled a 12 x 12 x 1.5" piece, so a square foot of this material and that works out to be 216 cubic inches, which is 0. pounds per cubic inch. If the density would accept the entire number it works out correctly to 7.4 but because it is rounding to 0.034 it comes out to 7.344 instead.

Want more information on bar grating products? Feel free to contact us.