in a bridge, how are strength and mass related?

Question

please be as specific as possible. thx

Answer 1

the point in designing a bridge is to minimise the mass while making sure it is strong enough. That is why all the funny designs with networks of bars going up above the bridge etc. They are ways to achieve this.

Generally more mass makes the bridge stronger, but the calculations are completely different fro different designs.

Answer 2

Do you really mean mass?

I suspect that you are confused and mean weight.

They're not the same thing.
Your science teacher at school should have told you.