Prologue

It is a conventional wisdom to maintain that the scientists and engineers, who earn a living by being engaged in applied mechanics, are divided into two groups: those in the first, traditional group deal with deterministic mechanics, whereas the representatives of the second, more recent, group devote themselves to non-deterministic mechanics. The traditionalists neglect uncertainties in the loading conditions, in the mechanical properties of structures, in boundary conditions, in geometric characteristics and in other parameters entering into the description of the problem at hand.