A review of fundamental stability concepts. Types of stability and buckling. Fourth - order differential equation of equilibrium of compressed bars. Buckling and stability matrix of elastically supported compressed bars. Buckling loads and effective lengths of compressed members. Applications on steel frames. The influence of boundary conditions on the effective length according to code provisions. Beams under combined compressed and bending. The influence of initial imperfections (load eccentricity - initial curvature) on the critical load. Elastic-plastic buckling. Resistance of compressed bars according to code provisions. Torsional and lateral-torsional buckling. Buckling of arches. Numerical applications via the FEM. Basic concepts of dynamic behavior of continuous elastic systems. Free and forced flexural vibration of beams. The 4th order differential equation of motion. Solution via the separation of variables method. Special cases of dynamic loads. Impact loading on bridges and cranes. The influence of velocity of moving loads on the dynamic behavior of beams and crane beams. Vibrations of steel pedestrian bridges, floor systems and stadium tiers under crowd loads. Avoiding human perception of insecurity. Application on fatigue problems of vehicle and railway steel bridges. Support settlements. Dynamic influence lines for internal forces and displacements. Axial vibrations. Torsional vibrations. Damping and energy absorption devices. Viscoelastic beams. Timoshenko beams. Dynamic stability of elastic systems. Numerical applications via the FEM.