For piezo-actuated structures a refined beam theory is introduced. In order to compare the analysis with previous investigations also the simple pin-force models are presented. The results obtained by these simple models for the static deflection agree well with the results obtained by the refined beam theory. However, the simple models are unable to predict the shear stress distribution in the bonding layer. Assuming ideal bonding between the piezoceramic elements and the beam a first approximation of the stress distribution in the bonding layer may be obtained by the refined beam theory. The results for the static case can be compared with results obtained by FEM. Especially for transient excitation of the piezoceramics the refined beam theory seems to have advantages in comparison with FEM.