Free vibrations of Timoshenko beams on two-parameter elastic foundation

The free vibration frequencies of Timoshenko beams on two-parameter elastic foundation are examined. Two variants of the equation of motion are deduced, in which the second foundation parameter is a function of the total rotation of the beam or a function of the rotation due to bending only, respectively. Both axial flexibilities and rotational flexibilities of the constraints are taken into account, and some numerical examples allow us to draw certain conclusions about the different behaviour of the two proposed foundation models.