Looking for some advice redesigning this piano moving ramp.

[Pianomoves]

Looking to design this Ramp to move pianos so it is lighter weight than the current design as I have an aluminium welder available.
Currently beams are steel Square SHS 25 x 25 with 18mm marine ply ontop.
Would you have any suggestions on changing from steel to aluminium frame and the plywood exchanged for some sort of aluminium top etc. Or even a whole new design.
Here are some pictures of the current design and dimensions of the ramp

https://imgur.com/a/qF6JF5J

The max weight of any piano moved will be 600kg distributed over the four wheels. 99% of any of my piano moves will be around 250kg
Grateful for any suggestions/advice

 

[BridgeSmith]

In order to get specific answers, you will need to provide more detail. What is the wall thickness of the square tube? How big are the caster/wheels on the 600kg piano? How is the weight distributed to the casters, i.e. what's the max weight on one caster? How far does the ramp have to span unsupported?

One thing I can tell you, aluminum is about 3 times more elastic than steel. A structural aluminum shape has about the same strength as A36 structural steel of the same section modulus, but will deflect about 3 times more under load. If your new ramp sags 3 times more than the current one, you'll need to consider if it will still work acceptably.

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

 

[Pianomoves]

Perfect, The wall thickness of the steel tube is 2.5mm
The wheels on the piano won't be an issue as the piano will be placed sideways on the Piano moving Dolly at all times when going over the ramp. The dolly wheels are spaced 500mm from each other in a squared layout.

I would also like to have the ramp be able to span 2100mm unsupported.
Thank-you for your time and help mate.

 

[BridgeSmith]

I would look into using aluminum channels. for comparison, the section properties for the structural tubing can be calculated here. If you set the inputs to metric(mm), enter the dimensions in mm, and then change the inputs to inches, it will convert the dimensions and the output to imperial units for comparison. You should find that a 2x1 aluminum channel is about twice as stiff (Ix is 6 times higher, but modulus of elasticity for aluminum is 1/3 that of steel, as mentioned in my previous post), 2 to 3 times as strong (depending on what the yield strength of the steel is), and weighs a bout half as much (area is 1.4 times larger, but aluminum is only 35% of the density of steel.

As long as the extra inch of depth isn't a problem, that would seem to be a significant upgrade, all around.

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