Abstract: This study investigates the effect of contact areas in the dynamic behavior of mechanical structures holding by bolts, highlight on the significant of nonlinear frictional force induced between the structural elements to control the structure vibration response. In this research, the nonlinear partial deferential equation describing the behavior of cantilever-layered beams has been derived. The equation has been formulated based on Euler-Bernoulli theory with coulomb friction model. Furthermore, an analytical solution of the derived equation for structures being in free vibration has been introduced. A structure includes two cantilever-layered beams connected by bolts has been assembled to validate the derived equation experimentally. A good agreement between the theoretical and experimental results has been obtained. Both results show that when the bolts of beams are loosed, then, the 2 beams will vibrate independently. But when the bolts tighten was increased, the stiffness and damping ratio of the beams were also increased until they reach to a certain maximum values at certain bolts tighten value. With continuing in increasing the bolts tighten, the value of stiffness was remained constant but the damping ratio was decreaseduntil it vanished when the bolts tighten becomes very large and the beams behave as 1 beam of double thick. Therefore, the bolts joints can be used to improve damping capacity of structure from adjusting each bolt tighten depending on the bolt location.