Using one element

I would like to prove that 3D structures are better for bridges.
But how should I test this hypothesis? And what is better?
As mentioned earlier there are various forces applied on a bridge construction.
Very often these forces are treated separately with separate constructions.
To make the bridge rigid en stabile some tie rods are applied or other stabilising elements. The bridge construction should in my opinion be one construction which deals with all these forces.
But not all forces are the same, for pressure and tension there are often different elements used. And if one uses different elements one is actually separating the construction again. So how can we make it a whole spatial construction?
Well you could use one element of a specified material and specified dimensions which deals with both tension and compression. In this situation the composition of these elements is the key to solving all problems: Strength, rigidity and making the construction stabile. Making the composition the solution of the problem is what I call ‘better’ in this case.

But how could we test this? I think the spaghetti bridge contest is a good context to test this with. It has two clear problems:
-A point load in the middle.
-A height difference between the supports.
The bridge has to carry its own weight as much as possible; this demands a perfect optimization between the number of elements used and the load that the total construction can bear.

In brief:
Which construction out of one type of element is the best for carrying as much weight as possible proportionally to its own weight?