Mechanical participation of interlayer on laminated glass for building applications

Romain Decourcelle, Jean Clément Nugue, Fabien Levasseur

In building applications involving laminated glass, no regulations exist today to consider mechanical participation of interlayer. The prEN13474 introduces the principle of effective thickness which allows consideration of the shear participation of the interlayer by the introduction of a shear transfer coefficient ω.

Many interlayer types exist on the market and a simple approach using a stiffness group have been established rather than consider each individual product. Based on Glass for Europe proposal, 3 stiffness families have been defined.

Experimental tests run by Dynamical Mechanical Analysis give mechanical properties of interlayer against temperature and frequency. Using this principle, we have built a large database with which we can quickly identify any interlayer to be measured. We can assess the shear modulus for a given temperature and load duration corresponding to a typical action defined in European Standard.

No analytical solution exists for complex behavior of large deflection in laminated glass plates under uniform pressure. We propose a numerical analysis using a finite element method which provides solutions of the plate’s bending behavior in line with experimental test data. Combined with the real values of the interlayer, a simple comparison with analytical formulas of prEN13474 gives us a chart for ω.

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