Testing Various Polymers for Suitability as Interlayer Between Glass Blocks

At Delft University a glass bridge will be built in 2017. The structural principle of the bridge is a Roman arch: solid glass blocks are stacked in a semicircle. Large compression forces are transferred between the glass blocks. Unevenness of the contact surfaces can lead to stress concentrations and cracking of the glass. Therefore the load has to be transferred by a ductile material in order to evenly distribute the stresses. This paper documents the research into polymers as that ductile interface.

The interface must:

– be clear and transparent.

– be ductile.

– UV resistant.

– have little time dependent deformation.

On this basis four polymers have been selected: Soft Polyvinyl Chloride (PVC), Poly Urethane (PU), Polyethylene terephthalate (PET) and Poly Carbonate. Lab tests are done to determine the stiffness of the polymer interlayer.

The compression stiffness of a polymer interlayer between glass blocks is quite complex to determine analytically. The Young’s Modulus, the Poisson ratio, the friction between the polymer and the glass, the stress and loading time all play a role. Using a FEM model, an attempt is made to gain some understanding of the influence of these parameters on the stiffness of the polymer interlayer.