Analysis of Laminated Glass Units

Laminated glass units used for glazing buildings consist of two thin glass plates bonded together by a thin core material, called polyvinyl butyral (PVB). As the plates are usually thin and undergo large lateral displacements, the conventional thin plate theory cannot be applied; instead, a nonlinear theory of plates has to be employed. As well, the interlayer, though soft in material properties, provides significant change in the overall behavior of the composite. Variational calculus and minimum potential energy theorem are employed to obtain the five nonlinear differential equations with appropriate boundary conditions; these equations are solved numerically with iteration. Experiments were conducted at the Glass Research and Testing Laboratory at Texas Tech University, Lubbock, Texas, to validate the mathematical model. Laminated glass units $1.524m\times 1.524m$ $(60\mathrm{in}\text{.}\times 60\mathrm{in}\text{.})$ in size with two glass plates each 4.763 mm (0.1875 in.) thick with a PVB of thickness equal to 1.52 mm (0.06 in.) were tested up to a lateral pressure of 6.895 kPa (1 psi). Lateral displacements and strains at four different locations at the top and bottom of the units were measured. The experimental results are compared with those from the mathematical model and presented in this paper.