I am helping a friend to design a concert hall. No need for
super architectural show off. Just a rectangular box. Knowing
that in my country constructions are done with reinforced
concrete and concrete blocks and that the hall's dimensions are,
length: 75 meters, width: 32m height: 9m, and that there should
not be any columns inside, what would be the size of the
columns, beams and roof slab ?