ABSTRACT
A dynamic magnification factor shows the number of times the maximum stresses and strains caused by dynamic load in the absence of gravity is greater than the corresponding stresses and strains due to static load equal to the maximal dynamic one. If the exciting frequency coincides with one of the natural frequencies, resonance might occur, i.e., the vibration process in which the amplitude of forced vibration is close to one of the local maxima at the given amplitudes of exciting load. In the case of a system with multiple degree of freedoms, resonance usually arises on low frequencies of natural vibration and manifests itself in great magnification of forced vibration amplitude due to the exiting frequency approaching the natural frequency. The fundamental problem of free vibration analysis is to find the natural modes and frequencies. The fundamental frequency is determined mandatorily, because the resonance on this frequency goes on with greatest amplitude and is most dangerous for a structure.
