Designed by structural engineer Eckersley O’Callaghan in collaboration with glass fabricator Cricursa, Vidre-Slide is a triangulated glass structure that is intended to test emerging technologies and maximise transparency by using long, tightly curved elements and minimal adhesive bonds without mechanical fixings.
Measuring four metres high and nine metres long, the slide comprises two glass elements propped against each other and tied together at the base by a steel structure, writes Eckersley O’Callaghan. The annealed glass is slumped to form 450mm-radius half-cylinder elements. Fabricated as single, nine-metre-long pieces without splices, they are laminated from two layers of 10mm annealed low-iron glass with a SentryGlas interlayer.
The curved form of the principal elements is central to achieving the structure’s long spans. Annealed glass provides better transparency than tempered glass and is sufficient to withstand the low stresses at play. The technique for forming long, tight-curvature glass was developed by Cricursa for a project in Hong Kong, in collaboration with Eckersley O’Callaghan.
The primary connections are formed using structural silicone, with a glass-to-glass mitred joint at the apex and glass-to-stainless-steel pinned supports at the base. The silicone transfers the forces that are fundamental to the stability of the structure without using mechanical fixings. A detailed finite element analysis (FEA) approach accurately determined the joint stiffness required to distribute the stresses safely.
The 42mm-diameter extruded glass rod treads are bonded using transparent silicone structural adhesive (TSSA) to the inside of the shorter glass element. The adhesive provides an almost invisible bond that is able to resist the shear load of a person ascending the structure. This is among the first uses of TSSA on a curved glass surface for a structural component.