Time-temperature superposition principle is widely used to generate interlayer modulus properties in the form of master curves for use in glass design. The process for generating a master curve can only be executed in a meaningful way for isotropic materials. The generation of master curves for multilayer interlayers, such as acoustic skin-core-skin tri layers, can therefore be problematic. In this paper, the behavior of a glass laminate containing a tri layer interlayer is determined by modelling the glass laminate in bending mode as a five-layer system (glass – tri layer (skin-core-skin) interlayer – glass) using the constituent material properties of the individual layers. The interlayer modulus, at which a three-layer system (glass-interlayer-glass) would behave the same way as the five-layer system for a given temperature and duration, is referred to as the effective modulus of the interlayer. This effective modulus is determined and can be used in conventional FEM software or analytical evaluation to model the behavior of the laminated glass, for a load scenario similar to the conditions for which the equivalent modulus has been calculated. The effective modulus obtained by modelling in this way should be comparable to a modulus determined through experimentation on actual glass laminates, and some initial results will be provided.