Primates Gallery at the Natural History Museum, South Kensington

Our original approach to glass floors was to design a thick slab of glass using high safety factors and then to place a sheet of acrylic under the glass to act as a 'safety net' should the glass crack. Further research has enabled us to refine our approach to stress factors. Glass strength reduces significantly if loads are constantly applied over a period of time. We have now developed a system where two sheets of glass are laminated together. The top sheet is designed for long term stress, the bottom sheet for short term emergency stress if the top sheet breaks, and the combined thickness of each sheet provides long term panel stiffness. These stair treads are an example of the laminated system. The treads are glued to the bronze supports using a structural adhesive.

Glass plates can also be bonded together to create truly composite structures. Conventionally in architectural structures the bonding materials are silicone or polyvinyl butyl compounds which have the advantage of low modulus, and are flexible enough to prevent stress concentrations occurring in the glass. However they also have low strength and tend to creep with time. Using stronger and 'stiff' adhesives we have engineered a number of complex structures such as these screens in the Primates Gallery at the Natural History Museum. In this instance an ultra-violet light cured adhesive (urethane methacrylate ester) has been used which is optically clear.

Architect Pawson Williams Architects
Client Natural History Museum