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Hello All,I am not sure if this is the right forum for this type of question.I am really looking for advice.I need to build ramps for one of our barges to drive dumptrucks on and off it.The ramps will need to be 14' long to have a decent approach angle. and probally 3' wide.Barge is 4' deep. Sits about 12" into the water.I am wondering if anyone has any thoughts on a high strength design for something like this?They will by hydraulic operated but weight still needs to be considered.We have ramps on another barge that we did out of 3 by 6 by 1/4 wall @ 12' long. They work but do have a bend to them now.I would say fully loaded truck weighs at least 55 000lb but would need a wide margin there.I have been thinking of heavier steel or plating the ramps top and bottom?Any and all thoughts are appreciated.
Reply:I would use beam as to not trap the water, thats my only advice.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:Hi,Like I- beam?
Reply:You can only use so much of a simple beam before it becomes a PITA. Heavy, and insufficient clearance under the ramp on the sides. I'd consider a lighter weight truss on top of the ramp, with sufficiently sized crossmembers (I'd imagine the wheel load will be close to the sides, so the crossmembers don't need to be totally massive, your load will be close to the truss). See someone about the proper way to design a truss for the loads you're considering. Offhand I'd say a good truss about 24-36" high would be good BUT I REALLY DON'T KNOW."Any day above ground is a good day"http://www.farmersamm.com/
Reply:I worked on the water all my life. Contact an engineering firm to design your ramps. I can just see the law suit now! Dont pay any attention to meIm just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:+1 on what CEP said. One truck in the drink and the cost of engineering will seem cheap.Mike
Reply:I agree with having it engineered providing the A&E guy don't tend to over engineer it to cover his butt at your expense.I think what you will discover they come up with will be a simple trussless design employing several parallel I beams for each ramp...The beams will be lightly cross braced and plated on top where the plates will be designed NOT to span the full width of all the beams, but instead be sliced narrow and each plate span only two beams and fully welded to tops of each beam their full 14' lengths....plating the bottoms will help you use shorter I beams providing they too are attached in same fashion.
Reply:I also agree with cep, on a project this big and in commercial use an engineered design is neccessary.Yeah, I know, but it'll be ok!Lincoln Square wave 255Miller Vintage mig30a spoolgunThermal Dynamics Pacmaster 100xl plasmaSmith mc torchEllis 1600 band saw
Reply:Plating on top and bottom do nothing to add ridigity or load capacity. It just adds weight and money. A very basic statics equation solves your problems, however you need some measurements a little more in depth than "decent approach angle" and "about 55,000lbs". You need some design parameters first.Capt. RyanRyanMiller Multimatic 200 tig/spool gun/wireless remoteMillermatic 350P, Bernard/XR Python gunsMiller Dynasty 350, Coolmate 3.5 & wireless remoteCK WF1 TIG wire feederMiller Spectrum 375 XtremeOptrel e684Miller Digital EliteMiller Weld-Mask
Reply:I agree in general that this should be an engineered design. The liability alone would justify the expense. Could somebody get killed it the ramps fail? Probably.Just thinking about it, 6 by 3 by 1/4 tubing does not seem like much for a concrete truck; you are probably lucky that you have not already dropped one into the river. I would start with the design that you have, and consider how to strengthen it. I certainly would inspect the existing design carefully to try to identify any cracks or distortions, which would help identify where the design needs to be stronger. I would not go for 50% stronger, I would want at least double the strength, if the old design bent. Triple the strength would probably be closer to the right answer, to get a reasonable safety factor. I usually start with a 4:1 safety factor; since it bent, the safety factor must have been minimal. However, the fact that you have working ramps made from 3 by 6 by 1/4 inch tubing gives you a place to start. If you went to 6 by 4 by 1/2 you would be roughly double the strength of the 6 by 3 by 1/4. So if the 3 by 6 by 1/4 works, but bends, double the strength would probably get you in the ball park. 6 by 3 by 1/4 is about 14 pounds per foot, 6 by 4 by 1/2 is 28 pounds per foot, which given that both are 6 inches high, double the weight should be about double the strength. A different approach would be to go to 8 inch tube, maybe 8 by 4 by 1/2. Without running the numbers, I would assume that 8 by 4 by 1/2 would be more than twice as strong as 6 by 3 by 1/4. All else being equal, the strength is roughly the square of the depth, so an 8 inch beam (tube) is around 77% stronger than a 6 inch beam. So an 8 inch beam, thicker, would almost certainly be twice as strong as what you have. Think 8 by 4 by 3/8 or 1/2. If I had to make a decision without a calculator and a handbook, I would go for 8 by 4 by 1/2, thicker and heavier. But the hydraulics would have to be rethought, since the weight would be more than double. If weight is a consideration, then one would want to go with deeper beams. For example, a 10 by 4 by 1/4 would be roughly three times as strong as 6 by 4 (or 3) by 1/4, without being twice as heavy. But can you live with deeper beams? How could the truck climb the 8 or 10 inch step?I would have to run the numbers to consider if one could plate the ramps and make them stronger that way. You would pretty much need to plate them top and bottom, with about the same thickness. When you only plate one side you move the center of the beam towards the plate, and it becomes "shallower" in that direction, which is not ideal. The plates would need to be continuous, so you would need to get plate 14 foot long. Theoretically, you could weld two plates together to get 14 feet, but I was taught that welds are not generally as strong as the base material. (Yeah, a great weld probably is as strong as the base material, but can you guarantee a great weld?) And the joint would be near the middle, the worst possible place for a possible weakness. Certainly you can get 14 foot long plate, but it might be special order. I would consider 12 foot plate and then welding on 2 more feet, that way the joint is away from the high stress area. But you would need to consider that you could not weld on the inside, as you would not have access to it, so the welding would be only on one side, not ideal..... Unless you put slots in the plate to give you a place to weld on the inside. But now it is getting more and more complicated, and probably not the way to go. In this kind of an application, I would try a few different designs, and compare strengths and weights. Given how short the beam is, I would think that anything strong enough would also be stiff enough. If it sags a bit from the weight of the truck, but goes back to the original shape after the truck passes, it probably does not matter. However, once I chose a design I would calculate the stiffness, to be sure. In practice, cost is generally a function of weight, so a lighter design would be cheaper as well. I am probably a bit less enthused about a truss, mostly due to the short length of the ramps. A truss would save weight but be complex to build and might be less durable.Could you live with a deeper beam? Could you live with a heavier ramp? You are going to have to have one or the other, probably both. I have basically just looked at this as a simple beam, but the exact design on each end could have a big impact on the results, especially given that the angle would vary, and the conditions on the dock side are likely to vary a great deal. The ends could in fact be the critical and most challenging part of designing this.The hydraulics are another consideration. The more one looks at a design like this, the more complex it is. It really merits some engineering time.Sculptures in copper and other metalshttp://www.fergusonsculpture.comSyncrowave 200 Millermatic 211Readywelder spoolgunHypertherm 600 plasma cutterThermal Arc GMS300 Victor OA torchHomemade Blacksmith propane forge
Reply:Originally Posted by xryanPlating on top and bottom do nothing to add ridigity or load capacity. It just adds weight and money. A very basic statics equation solves your problems, however you need some measurements a little more in depth than "decent approach angle" and "about 55,000lbs". You need some design parameters first.Capt. Ryan
Reply:We built a set to put 300 ton crawlers on barges PE dwgs W 14 coverplated with 1/2 plate.
Reply:Assuming two narrow ramps. Each holding approximately 20,000lbs (tandem axle gvw of 40,000lbs divided by two). Back end of the truck on the ramp at the mid point. Two beams carrying the load on each ramp(10,000 each).You gotta fail At the very least, the steel will go plastic, and deform. At the worst.......call a wreckerFor some reason I did 15' instead of 14', but you get the picture."Any day above ground is a good day"http://www.farmersamm.com/
Reply:that example of deflection would make an excellent ramp design ,just flip it over , After all the Army scissor bridge will carry a 60 ton tank . You must be using small dump trucks most of the ones I know of go 57 to 62,000# , and we are not even talking mixers.
Reply:Hey Farmersamm, What are you using for moment calculation there?SqWave 200Millermatic 190Airco 200 ACHypertherm PM45Boice-Crane Band SawVictor O/A |
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发表于 2021-8-31 22:39:53