Composite structural elements of steel-concrete began to be used only in 1960 after the development of methods and constructive dispositions that ensured the functionality of these two materials together. In order to verify the importance of the participation of the axial mode in the frequency spectrum of the free vibration problem in composite beams with deformable shear connection, several analyses for 4 different boundary conditions and stiffness connection variation were performed. The analysis of the problem was carried out by development and computational implementation of a finite element for composite beams with partial interaction in the longitudinal direction applied to the problem of free vibrations. The solutions to this problem in the literature are scarce, and project recommendations are simplified. The results show that the finite element exhibits an excellent performance compared with the analytical results and as the axial mode has a high modal contribution, despite the boundary condition and stiffness connection.