Enhanced Effective Thickness of multi-layered laminated glass

Abstract

The stiffness and strength of laminated glass, a composite of glass layers bonded together by polymeric interlayers, depend upon shear coupling between the glass plies through the polymer. In the design practice, this effect is commonly considered by defining the effective thickness, i.e., the thickness of a monolith with equivalent bending properties. Traditional formulations have been proposed for a package of two layers of glass and one polymeric interlayer, but their extrapolation to a higher number of layers gives in general inaccurate results. Here, the recently-proposed Enhanced Effective Thickness method is extended to the case of laminated glass beams composed i ) by three layers of glass of arbitrary thickness, or ii ) by an arbitrary number of equally-thick glass layers. Comparison with numerical experiments confirms the accuracy of the proposed approach.

Effective modelling of structural glass with laminated shell elements

“…However, it has been pointed out by Galuppi and Royer-Carfagni that for the cases where the glass plies or the interlayers are not all of the same thickness, different effective thicknesses may be obtained depending on the chosen sequence of layers [7]. Another drawback of the generalised formula is that the effective thickness definition for maximum ply stresses is quite ambiguous, and the stress-effective thicknesses for internal layers can never be calculated [7].…”

“…Another drawback of the generalised formula is that the effective thickness definition for maximum ply stresses is quite ambiguous, and the stress-effective thicknesses for internal layers can never be calculated [7].…”

“…Galuppi and Royer-Carfagni [6][7] noted that the effective thickness approach in ASTM E1300-12a is accurate only for simply-supported beams under uniformly distributed loading and in those cases where the deflected shape is similar to this reference case. For other loading cases and for LG plates and shells, the above formula may not capture the structural response well.…”

“…The fundamental idea of such approaches is to establish an effective monolithic thickness based on the material, geometry, and loading conditions of the considered LG beam, and to use a monolithic plate/shell model with this effective thickness and the same loading and boundary conditions for the prediction of the maximum deflection or stresses in the glass plies. Although the shear transfer capacity of the PVB interlayer is considered in the effective thickness approaches, their accuracy depends on the considered geometry and loading and boundary conditions [6][7].…”

Glass fins with embedded titanium inserts for the façades of the new Medical School of Montpellier

“…This value is extremely conservative for a SentryGlas® interlayer. For a more accurate calculation, the effective thickness can be calculated according to Galuppi and Royer-Carfagni (2014). For a 4 × 10 mm laminate with 1.52 mm SGP, a distance of 3450 mm between restraints, supposing a simply supported beam with a uniform distributed load and a conservative shear stiffness of G = 0.97 MPa (60 • C 10 years), the effective thickness is 32.9 mm.…”