Buckling of multilayered laminated glass beams: Validation of the effective thickness concept

Stability of laminated structural glass is one of the design requirements to be considered due to the brittle and slender nature of this kind of glass elements. Since laminated glass is mainly manufacture with viscoelastic interlayers, its mechanical properties are temperature and time dependent. This implies that, i.e., the critical load of a laminated glass beam subject to constant compressive load decreases with time as well as with temperature.In this paper, the equations of the Euler Theory for buckling of monolithic beams are extended to multi-layered laminated glass beams using an effective stiffness. This proposal is based on the idea of calculating the thickness (time and temperature dependent) of a monolithic element with bending properties equivalent to those of the laminated one, that is, the deflections provided by the equivalent monolithic beam are equal to those of the layered model with viscoelastic core.In this work, the analytical predictions are validated by compressive experimental tests carried out on a simply supported beam composed of three glass layers and two polyvinyl butyral (PVB) interlayers. Moreover, a finite element model was assembled to validate the proposed methodology for any boundary conditions. The results shown that a good accuracy can be obtained with the proposed equations being the errors less than 7% for all the experiments and simulations considered.