Things I Got Wrong

(While doing structural dymanics calculations) The moment of Inertial (I) used in Stiffness, flexibility or other calculations e.g. k = 3EI/L³ is not mass moment of Inertial. It is second moment of Area.

The mass of structure doesn't play role in the stiffness. Only the material (E) and it's geometry (I, L) does. Mass may later be added as load.

While using Manning's equation be sure that the units are in SI. This relation is not dimentionally valid and thus the manning's coefficient works only for SI unit.