Bridge Making
Buckling under compression
Crushing under compression
Buckling under shear
Pulling apart under shear
Effects of bending
Effects of torsion
Scale is the clue. As Galileo said, doubling the the length, width, and height of an object increases its area by a factor of four, and its volume and weight by a factor of eight.
Remember that materials such as popsicle sticks and more especially balsa wood are anisotropic, that is, their properties differ with direction.
Why not just glue the wooden strips together?
After a test, you could ask - "Did it fail at a joint?" - "Did a single member fail?" - "Were there members that were never highly stressed?" - and so on.
"So just concentrate on each and every stick and apply a force of win in ur bridge.....".