resistance to bending angle or tube which is more resistance

Want to build a gravel screen to sort out over size rocks from sand. The gravel and rocks would be dumped on grizzly bars on a 40 degree incline
and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under t he grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped abou t 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowl y dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pou nds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel
thank you for replying it is much appreciated.
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On Friday, February 10, 2017 at 6:13:43 PM UTC-5, lakeside bob wrote:

ne and the gravel and rocks would slide down the slope rocks sliding off t he top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches.

on the grizzly bars?

out 18 inches on to the bars.

wly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 p ounds.

The last one will bend the least, by far. The stiffness of the angles will depend on how they're oriented, but neither one is even close to the tubes, no matter how you arrange them.
--
Ed Huntress


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On Friday, February 10, 2017 at 6:13:43 PM UTC-5, lakeside bob wrote:

ne and the gravel and rocks would slide down the slope rocks sliding off t he top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches.

on the grizzly bars?

out 18 inches on to the bars.

wly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 p ounds.

You provided a lot of information, but not quite enough. How long are the bars? Are there any supports other than at the ends? When you dump a load on to the bars how many bars got the load. How are the bars supported at the ends. Welded or sitting on top of a r? Why 36,000 steel. Low alloy w ould probably be cheaper for equal strength.
Dan
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On Friday, February 10, 2017 at 8:14:34 PM UTC-5, snipped-for-privacy@krl.org wrote:

line and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars und er the grizzly bars to be picked up and moved to usage area. the rocks move d to waste area. Spacing between bars would be 3 inches.

d on the grizzly bars?

about 18 inches on to the bars.

lowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds.

e bars? Are there any supports other than at the ends? When you dump a loa d on to the bars how many bars got the load. How are the bars supported a t the ends. Welded or sitting on top of a r? Why 36,000 steel. Low alloy would probably be cheaper for equal strength.

If by "bending" he's referring to stiffness (resistance to springing, not r esistance to permanent bending), then the alloy makes no difference at all. 36,000 psi tensile-strength steel us just as stiff as 200,000 psi hgh stre ngth alloy.
If he's referring to permanent bending, then a little deeper section of low -strength steel is still 'way less expensive than a lesser depth of high-st rength steel.
--
Ed Huntress

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On Friday, February 10, 2017 at 5:13:43 PM UTC-6, lakeside bob wrote:

ne and the gravel and rocks would slide down the slope rocks sliding off t he top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches.

on the grizzly bars?

out 18 inches on to the bars.

wly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 p ounds.

OK some more information. Bars will be 8 feet long with a support under each one three feet down from the top of the sloping deck. The bars will be welded to cross tubes of 3 x 3 x 1/4 inch steel at the top of the frame and bottom along with one at 3 ft down from the top of frame. the 36,000 pound steel is what the local shop sells. the wheel loader bucket is 8 feet long or wide, so with the cap between bar s at 3 inches and each bar being say 3 inches wide the gravel will be dump ed on 16 or 17 bars.
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On Sat, 11 Feb 2017 08:43:58 -0800 (PST), snipped-for-privacy@tisovich.com wrote:

I'd say the 2.5 X 2.5 angle, particularly if you weld 1/4" plate across the bottom.of the angle, but I'm not an ME.
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On Saturday, February 11, 2017 at 12:01:33 PM UTC-5, Clare wrote:

cline and the gravel and rocks would slide down the slope rocks sliding of f the top of the grizzly bars, and sand falling between the grizzly bars un der the grizzly bars to be picked up and moved to usage area. the rocks mov ed to waste area. Spacing between bars would be 3 inches.

ed on the grizzly bars?

about 18 inches on to the bars.

slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,90 0 pounds.

rom the top of the sloping deck. The bars will be welded to cross tubes of 3 x 3 x 1/4 inch steel at the top of the frame and bottom along with one a t 3 ft down from the top of frame.

This is a duck-soup-simple statics problem taught in elementary engineering and technology classes all over the world. Any decent book on statics and strength of materials will show the solutions in a minute, with very simple formulas for solving a particular question.
But my statics book is in a box in my attic, and I'm too warm and comfortab le where I am. d8-)
--
Ed Huntress

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Just to get you started, the spec that determines how stiff a beam will be is the moment of inertia, and you can look it up in tables for standard structural beams. Assuming the angle is oriented with one flange horizontal and one vertical, and the load is in the vertical plane:
2x2x3/8 angle 0.473 in^4 2.5x2.5x1/2 angle 1.219 3x3x1/8 tube 1.851 3x3x1/4 tube 2.888
So, the 3x3x1/4 wall tube is 2.888/0.473=6.1 times stiffer than the 2x2x3/8 angle. In another post you say that each beam will be 8' long and supported 5' from one end,m and I'm going to guess the grate will be 3' wide so with 3" bars and 3" gaps that's 7 bars so 4900 lbs./7p0 lbs. per bar. I'm not an ME but I like to use a program called engineering power tools for stuff like this (http://www.pwr-tools.com /). According to it, a 5' beam of 3x3x.25 tube simply supported at each end (I'm assuming the end beam can twist a bit) with a load of 700 lbs. uniformly distributed will flex 0.023" and the maximum stress will be 2700 psi. That stress is about 1/13 of the tensile strength which looks good, but in reality if you dump the load on all at once the peak load will be at least 3 times the static load, and you don't know if the load will really be exactly uniformly distributed, so your real safety margin is more like 4x which still should be good. The deflection and the peak stress are inversely proportional to the moment of inertia, so if the beam is twice as stiff the deflection and peak stress will be half. Going to 3x3x1/8" wall square tubing raises the deflection to 0.036", the peak stress to 4210 psi, and the safety margin drops to about 2.8. I wouldn't go less than that even if no people will be on or under the grate without a much more careful analysis, and if I just wanted to be sure I was only going to build it once I'd go with the 3x3x1/4 tube at the least. Going to a stronger alloy won't change the deflection (which is so small it shouldn't be an issue anyway) but will raise the tensile strength so you could go with smaller tubes to support the weight, but you won't save money so why bother. The real problem you will eventually have is wear as the rock and sand grind away your tubes. If that's a real issue you could weld on flat tops of armor plate as needed, but again, it might just be cheaper to buy more mild steel tube. The more you buy the cheaper per pound, so build it once and see how long it lasts, then buy enough tubing for 2-5 more :-). Remember, I'm not an ME and this is just for fun and probably worth what you are paying for it :-).
----- Regards, Carl Ijames
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On Sat, 11 Feb 2017 13:49:38 -0500, "Carl Ijames"

That's fine, but to be a "grizzly bar" it will "likely" be mounted with the angle up, and the open end down, which changes things significantly.

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On Saturday, February 11, 2017 at 7:42:06 PM UTC-6, Clare wrote:

Hello Carl Ijames Yes the angle iron would be welded with the angle iron joint facing up so the gravel would flow off the down sloping sides. Do think the other people who replied thought that it would be mounted differently? What do you think the stiffness and resistance to bending would be compared to the square tubing if the angle is mounted with the angle pointed up?
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wrote in message wrote:

Hello Carl Ijames Yes the angle iron would be welded with the angle iron joint facing up so the gravel would flow off the down sloping sides. Do think the other people who replied thought that it would be mounted differently? What do you think the stiffness and resistance to bending would be compared to the square tubing if the angle is mounted with the angle pointed up? ====================================================================The moment of inertia for 2x2x3/8" angle with the angle up and the legs at 45 degrees is 0.203, versus 0.473 with one leg vertical so it weakens the angle substantially. I've no experience with a grizzly so I can't offer any more detailed advice, sorry.
----- Regards, Carl Ijames
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On Saturday, February 11, 2017 at 10:44:00 AM UTC-6, snipped-for-privacy@tisovich.com wro te:

line and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars und er the grizzly bars to be picked up and moved to usage area. the rocks move d to waste area. Spacing between bars would be 3 inches.

d on the grizzly bars?

about 18 inches on to the bars.

lowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds.

om the top of the sloping deck. The bars will be welded to cross tubes of 3 x 3 x 1/4 inch steel at the top of the frame and bottom along with one at 3 ft down from the top of frame.

ars at 3 inches and each bar being say 3 inches wide the gravel will be du mped on 16 or 17 bars. OK some more information, the width of the grizzly box is 10 feet wide that the 8 foot wide wheel loader bucket will be dropping the gravel onto.
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On Sat, 11 Feb 2017 08:43:58 -0800 (PST), snipped-for-privacy@tisovich.com wrote:

May be irrelevant for your issue, but the commercial versions I have seen the rock is dumped in a hopper and a vibratory feeder sends it slowly to the grizzly. Normal oversized is much smaller than you are dealing with but winter time gravel 'ice burgs' can be much larger.
Will try to get out and take a closer look tomorrow...
--
William

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You might try wood, especially if you want to test the dimensions to see if they are adequate. A 3 by 8, ie 2 2 by 8s held together, has about the same flex as the 3 by 3 by .25 steel tubes and shows around 500 psi max stress with a 1000 lb load. You might put some iron channel stock on the top of each bar to make it last a little longer.
Hul
snipped-for-privacy@tisovich.com wrote:

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On Sunday, February 12, 2017 at 6:24:09 PM UTC-5, Hul Tytus wrote:

ncline and the gravel and rocks would slide down the slope rocks sliding o ff the top of the grizzly bars, and sand falling between the grizzly bars u nder the grizzly bars to be picked up and moved to usage area. the rocks mo ved to waste area. Spacing between bars would be 3 inches.

ped on the grizzly bars?

d about 18 inches on to the bars.

slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,9 00 pounds.

from the top of the sloping deck. The bars will be welded to cross tubes of 3 x 3 x 1/4 inch steel at the top of the frame and bottom along with one at 3 ft down from the top of frame.

bars at 3 inches and each bar being say 3 inches wide the gravel will be dumped on 16 or 17 bars.
Clever.
--
Ed Huntress

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