Application of piezoelectric elements to active reduction of bending vibrations of the beams is known well in the literature. During vibrations, an external excitation may vary in the time domain, including its form in the frequency domain. It should have influence on their response. The problem of proper selection of the control parameter in the control algorithm used to reduce vibrations arises. In the article, simulations of a control algorithm based on detection of bending moment are analytically tested. The solution for the transient type of vibrations are obtained by the finite difference method (FDM). Analysis for two separated natural modes was performed. The analysis shows the possibility to design a control algorithm based on detection of the bending moment.