Interlayer modulus properties in contemporary European standards

Interlayer modulus influences the stress laminated glass experiences under load. The determination of interlayer modulus data is complex, and until recently the design engineer would rely in most cases on interlayer modulus properties as determined on the foil, as published by the interlayer producers. Recently, standards or approvals have become available that provide guidance for interlayer modulus data for different interlayer product categories as either fixed values for a certain load scenario, or more generic material models. Data for regular PVB, structural PVB and ionomer products are available from e.g. prEN 16113 (2017), Dutch standard NEN 2608 (2014/2019), Norwegian standard NS3510 (2015) and German national approvals as associated with use of DIN 18008 (2011-2016). This work aims to provide an overview of the different modulus values available for each of the interlayer categories in the different existing standards and other sources in a normative framework. With the work in CEN/TC250/SC11 on a Eurocode for structural glass progressing, this will remain an active area for development for the foreseeable future. A consistent approach to the representation of interlayer modulus properties would support the internationally active design engineer.