3/15/2024 0 Comments Mcnichols bar grating load tables![]() And, the other wheel in that axle line (on the same effective width of grating) might be another 20% and only 2’ away, thus two point loads on the effective width of grating bars. I agree with Jayrod12, I can imagine 50-60% of the total weight of the machine on one wheel under the worst conditions. RE: Scissor Lift on Grating human909 (Structural) 7 Nov 19 21:01 If you are unable to make sure that the unit won't be used while it sits on the grating, make sure you factor in the recomended lateral loads for construction work platforms in ASCE 37 (I don't have it in front of me but I believe it's 50#/worker or 2% of total load, whichever is greater). Unless you're going to lay plate over the entire walking surface (slip hazard, and heavy - the structure may not be able to handle it) or have a group of people picking up and moving steel plates from behind to in front as it moves, it doesn't sound like a practical way to solve the problem. The difficulty here is that you're looking at a moving load. The spring constants of the supports will be based on the flexural stiffness of the bars at that point. Essentially, you'd have a point load in the center of the plate (+/- some reasonable distance) supported on several springs. To analyze a plate to spread the load, you'd have to look at the relative stiffness of the bars and the plate. RE: Scissor Lift on Grating human909 (Structural) 7 Nov 19 19:50 That wheel load is all on those 6 or 8 grating bars. or channel will bring more grating bars into play. or channels and the grating, you want to match the deflections of the two systems, which then determines the load distribution to X number of grating bars. As a function of the relative stiffnesses of the pls. ![]() or the channels atop the grating, become a gridwork of beams in terms of carrying and distributing the wheel loads. It seems to me that there might be plenty of times when you could have two wheels on the same effective width of grating, so look at that too.Įdit: The pls. That quickly leads to instability on that narrow a machine. I agree with the above, that wheel deflection and basket translation at full extension, may be just as important as actual grating carrying cap’y. This would add some weight and fiddling during machine movement, needing 4 pieces in total, but it would also distribute the load to an extra 8 or 10 bars in the grating, increasing the effective beam width. ![]() Maybe 8” wide channels, 6-8’ long, with upturned flanges, would be even better than pl. Why not add a couple steel plates under the wheels, maybe 1’圆’x.5” thk. I'm mechanical, not structural so I'm not sure if this math checks out, it makes intuitive sense to me, but any advice would be greatly appreciated. I used example 2 with the only changing being K ( I used 3.78947 whereas they used 10.1), there are only that many bars supporting load for the tire width given above 4.5".Ĭ = 4Mw/L = 252.42 lbs (much less than 687lbs)įor my load I just divided 687/252.42 because load/displacement linear relationship, and then multiplied Dc by this value to get I utilized the Metal Bar Grating Engineering Design Manual found here. The largest span that I measured was 76". Its Galvanized steel with an allowable design stress of 18,000psi, and Young's Modulus of 29E6 psi. The grating is McNICHOLS (3/16 by 1 1/2 with a c-c distance of 1.1875"). The scissor lift is a Genie 1930 model, and weights 2748lbs, I'm assuming a concentrated load of 687 (one tire, which is not conservative, because tipping could occur, but even so it fails). New Member here, and I have seen a few of the other post about scissor lift on gratings but am still unclear on how to go about determining the load capacity of grating given a contact patch of about 4.5" (tire width) by 4" (tire length).
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