The present study investigates the stiffening effects of a simply supported and clamped–free symmetric piezolaminated composite type beams. The structure consists of PZT layers or two sets of patches bonded to the surface of the beam. The analysis considers the linear piezoelectric constitutive relations and a first order shear deformation theory (FSDT). The influence of the actuators is evaluated by means of the pin-force model and their size and location along the beam are taken into account. Two coupled equations of motion for the lateral displacement and bending rotation and one uncoupled equation for the axial displacement of symmetric piezolaminated composite beam are solved numerically to obtain the natural frequencies and mode shapes. Numerical experiments demonstrate that the natural frequencies and mode shapes of the beam can be actively altered using the piezoelectric bonded actuators. The results of the present degenerated model are compared to results presented in the literature. The comparisons yielded excellent matches.