Geometric, static and material nonlinearity. Theory of first and second order. Definition of stability. Bifurcation theory. Linear theory of first and second order. Eule's cases of buckling. Buckling length. Differential equation of bending of rod. Evaluation of rod stability parameters. Stability of rod systems. Displacement method. Modelling the nonlinear structure behavior. Finite element method. Dynamic load action. Dynamic model of structure. Differential equations on system motion with one or more degrees of freedom. Free and forced vibrations of the system with one degree of freedom with and without damping. Free and forced vibrations of system with more degrees of freedom. Earthquake action and structural response. Method of analysis structures for seismic action. Principles of aseismic design of buildings.