Mechanical properties of solid

[starablaze]

why are pillars and columns and railway lines 'I-shaped'? how is buckling prevented? howis the weight distributed?

 

[granpa]

most of the strength of a beam comes from the top and bottom parts.

 

[russ_watters]

Stiffness is a function of moment of inertia: http://en.wikipedia.org/wiki/Moment_of_inertia

Using the concept properly enables saving on materials (saving weight and money) while maximizing strength.