Weight Distribution Across Multiple Support Points (Load on Trailer)

[Ahmed]

TL;DR

Weight Distribution Across Multiple Support Points

Hi All,

Please note that I am looking for a methodology to calculate load distribution on multiple supports (3 and more)located underneath a heavy object at different spans/locations from the objects CoG, please see below example:
View attachment 336373
I searched here in Physics Forums and found article gave solution on simple 2 points support only.
Could you help me to find that please ?

Thanks,
Ahmed

 

[berkeman]

Welcome to PF.

Does each wheel or axle have suspension ("sprung")? If not and they are rigidly attached to the rigid frame, do you see an issue with this calculation?

 

[Ahmed]

Welcome to PF.

Does each wheel or axle have suspension ("sprung")? If not and they are rigidly attached to the rigid frame, do you see an issue with this calculation?

Hi Berkeman, yes they are on suspension, but I want to know the concept on how to distribute the loads on the saddles to assess the bending moment on the trailer deck (I have the load on each axle line).

 

[Baluncore]

Is the object more rigid than the trailer ?

You must solve for a distribution of the object's mass, to the individual load-carrying points selected on the trailer deck.

The weight applied to each of the load-points, should sum to the weight of the object.

Consider the point on the trailer deck below the CoG. The moment of the applied load forces, about that point, should sum to zero.

Now you select convenient load points on the trailer deck, then solve the linear system to find the load applied to each.

 

[Lnewqban]

Welcome, @Ahmed !

Please, check solutions to problems 251 through 257.
Those may help you to see the best way to approach yours.

https://mathalino.com/reviewer/mech...ution-to-problem-251-statically-indeterminate

 

[Ahmed]

Is the object more rigid than the trailer ?

You must solve for a distribution of the object's mass, to the individual load-carrying points selected on the trailer deck.

The weight applied to each of the load-points, should sum to the weight of the object.

Consider the point on the trailer deck below the CoG. The moment of the applied load forces, about that point, should sum to zero.

Now you select convenient load points on the trailer deck, then solve the linear system to find the load applied to each.

 

[Ahmed]

Hi Baluncore, The issue is I don't have the option to choose the load points on trailer deck, the horizontal vessel or steel bridge it has their own saddles/support points which I've to deal with it, so i need a calculation to tell me how much load will be transferred from the vessel/bridge to the trailer deck through the saddles/supports based on location of each saddles/supports from the CoG.

 

[Baluncore]

The issue is I don't have the option to choose the load points on trailer deck, the horizontal vessel or steel bridge it has their own saddles/support points which I've to deal with it, ...

The decision has been made for you, because you have decided to use the available points. That is as expected.
Now you must allocate the total load to those points, with sum zero moment.

 

[Nik_2213]

So you need sub-frames etc to spread the point loads more evenly across the trailer bed...

 

[Baluncore]

So you need sub-frames etc to spread the point loads more evenly across the trailer bed...

Adding sub-frames would increase the load mass, and increase the load height. That would reduce stability, and might impose travel route restrictions.

The trailer bed is a truss, with a linear stiffness matrix. The bed is designed to be a sub-frame, placed between the axle suspension points, and the intended loads.

If needed, timber packing between the load-points and the bed, will adjust the load applied at each position along the deck. In many cases, timber will also increase the surface compliance, and the friction coefficient.