Modeling of the structural behavior of multilayer laminated glass beams: Flexural and torsional stiffness and lateral-torsional buckling

In recent years several investigations were performed about the behavior of laminated structural glass elements, namely in terms of their flexural and torsional stiffness, with the lateral-torsional buckling of beams being one of the most relevant and complex topics. Various analytical formulations were proposed to describe the equivalent stiffness of laminated elements; however, none covers more than three layers of glass in a comprehensive and unified manner, and those that exist are not consensual. This work proposes a new formulation, based on sandwich theory, which provides equivalent results to previous formulations in a limited set of conditions, but that is also able to characterize the behavior of simply supported laminated glass columns and beams up to five layers, subjected to compressive axial loads, mid-span loads, uniformly distributed loads, four-point bending, pure bending or torsion. The fundamentals of the formulation presented in this paper allow it to be extended to a larger number of layers and to different load and support conditions. The proposed formulation is assessed by means of a parametric study based on the comparison with numerical results retrieved from finite element simulations, in order to assess the range of validity of each expression. Two analytical approaches for the lateral-torsional buckling problem are studied in detail, with their fundamentals being explained. Another formulation, proposed in Australian Standard AS 1288, is also addressed. An experimental assessment of the work developed is achieved by comparing the results from flexural tests available in the literature with analytical and numerical predictions.