ABSTRACT
This chapter investigates the flexibility matrix properties by means of Clapeyron’s theorem. This theorem is formulated for the general case of an elastic system and was proved by French physicist and railroad engineer Benoit Clapeyron in the year 1833 for the particular case of a single body keeping equilibrium under load. The strain energy of an elastic system, which is in equilibrium under a given loading, is equal to half the work done by the external forces, acting through the displacements of the system from the unstressed state to the state of equilibrium. The named matrix is the flexibility matrix for the totality of redundant forces acting in the primary system.
