Resumen
This work deals with the problem of free vibrations of uniform beams with elastically restrained ends and with two internal translational elastic restraints. The main objective of this work is
to obtain the minimum stiffness of the internal elastic restraints that raises a natural frequency to itsupper limit. The minimum stiffness is determined by using the derivative of the function which gives
the natural frequencies, with respect to the support position. The problem is solved with the close form solution. The effect of mode shape shift caused by changes in the rigidity parameter of theinternal translational elastic restraints is analyzed. Additionally, results of the frequency parameter and modal shape of beams with different end conditions are presented.