Practical expressions for the design of laminated glass

Abstract

Due to deformability of the polymeric interlayer, stiffness and strength of laminated glass are usually less than those corresponding to a monolith with same total thickness. A practical design tool consists in the definition of the "effective thickness", i.e., the thickness of an equivalent monolithic glass that would correspond to the same deflection and peak stress of the laminated glass, under the same constraint and load conditions. Very recently, a new model has been proposed for the evaluation of the effective thickness. Here, a comparison is made with the classical approach by Wölfel-Bennison and the new method is specialized to the most common cases of the design practice, providing synthetic tables for ease of reference and immediate applicability.

Enhanced Effective Thickness of multi-layered laminated glass

“…If the thickness of the glass layers is constant, the expressions (3.18) and (3.19) provide a ready-to-use practical tool for the design of laminates formed by an arbitrary number of layers. The coefficients needed for these calculations are similar to those obtained for the case of a three-layered beam (two glass layers and one interlayer) and recorded in [17]. The results that can be obtained are in excellent agreement with numerical experiments, performed with accurate three-dimensional models.…”

“…Remarkably, these data are identical to those recorded in [17] for a three-layered beam. Indeed, (3.17) represents the natural extension of the corresponding expression obtained in [13].…”

“…Analogously to Section 2.3, the minimization of such energy with respect to the parameter η and β leads to 17) where the coefficient Ψ is again given by (2.36) and recorded in Table 1 for several cases of relevant importance. Finally, in analogy with equations (2.37) and (2.39), it can be shown that the deflection-and stress-effective thickness can be defined as…”

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“…In [Galuppi and Royer-Carfagni 2012] we treated the classical problem of a composite laminated glass beam under flexure using a variational approach similar in type to that proposed in [Aşik and Tezcan 2005] for numerical purposes. Using convenient shape functions for the beam deflection, simple formulas for the effective thickness were obtained which, for the one-dimensional case of beams with various constraint and load conditions, fitted with numerical experiments much better than the classical expressions (1-6) and (1-7).…”

“…where, as explained in [Galuppi and Royer-Carfagni 2012], the shear coefficient of the intermediate layer χ is evaluated as χ = t 2 /H 2 and β is another parameter that depends upon the load condition. For simply supported beams, the corresponding values of β are recorded in [Wölfel 1987] for various loadings.…”