Design Question

[Jacobs]

I am in the process of building a ramp to load my boat trailer on top of my pickup. I would like to fabricate the ramps from sheet steel as shown in the drawing. My current idea is to have the ramp 6 inches on the bottom with 3 inch sides and a 1 1/2 inch return bend for strength.



The ramps will be 84 inches long and each one will need to support a load of 1000 lbs.



What thickness of steel would be required to accomplish this task? If you have other suggestions, please comment.



Thanks in advance



Bruce

 

[TPCDrafting]

I just checked my AISC manual and if you wanted to just buy some channel stock cut to 84" (7 feet) you would have the following results:

If you choose C6x?? the 6 designates the outside depth. It doesn't give the dimension for the thickest part of the side flanges, only the average which for all the C6 series is 5/16" Figure 3/8" worst case, but that's each side so your down to 5 1/4" in the bottom of the trough where the tire travels. I would step up to the C7 series where the average is now 3/8" which still gives you 6 1/4" in the trough. So with that in mind the C7 series comes in 3 sizes (my manual is old, there may be more. ) The sizes are:

C7x9. 8 (T sub w OR plate thickness of 3/16")

C7x12. 25 tw=5/16

C7x14. 75 tw=7/16



The second number is the weight in pounds per linear foot. So think the C7x9. 8 X 7 feet = 68. 6 pounds per ramp. I don't have the numbers to check if the smallest will do the job, but that sure would be heavy enough ramp for me to lug around. If you buy 3/16" plate material and fab it your self, plan on them weighing in this neighborhood.

I built my ramps also, but I built them like you see on equipment trailers in a ladder configuration. Mine are only 5 feet long, using L2x2x3/16" stock. I've driven cars and jeeps onto the trailer using them and they don't even seem to flex much. They only weigh about 45 pounds each.

 

[Jacobs]

TPC



Thanks for the reply.



I have a set up now that uses some 2"X8"X7' foot scaffold plank. It works OK but I get nervous when I see the bend in the plank. I have trussed the bottom with a piece of flat stock and a wedge. The Lift & Load video I saw has a light steel ramp that looks better to me than the channel. I know that the channel will work but I need to carry 4 pieces and the weight adds up. The only load these ramps will see will be the weight of a 16' Lund Explorer, the trailer and a 40hp Merc. Total weight 1895 pounds.



One of the people I work with suggested 16 gauge galvinized sheet. Any thoughts from those with experience??



I have thought of using 2"X8" white oak. That would do the job but it takes a lot of space.



Take care



Bruce