Reflexions is a 12m high sculpture conceived as a 3D glass scaffolding exhibit in Paris in the fall of 2023. The design of the structure is based on the concept of a modular assembly in the to be easily assembled and dismantled in different location in the world. The connexions are bolted on-site, with stainless steel connectors bonded with epoxy directly on the laminated glass bars.
The 3D scaffolding principle raises the challenge of the structural predictability of a highly redundant glass structure whereas the usual approach would prefer an isostatic fail safe structure. This paper gives an inside view of the process designing a glass structure rely on epoxy adhesive for the connections. The design strategy is based the control all the parameters source of the scattering of the structural response in order minimise uncertainty in the structural resistance. The details and assembly are designed to reduce all eccentricities and imperfections due to either fabrication, manufacturing, or erection on site since any deviation would cause a possible different load path and a possible higher local stress concentration at nodes. In particular, the node was carefully designed to ensure that every component (glass, glass surface, steel surface, adhesive, steel welding, …) fulfils its predicted role minimising stress concentration in the glass or delamination in the adhesive. Planarity of gluing surfaces, adhesive thickness, node tolerances, where the primary parameter for improving the reliability of the node.
On the other hand, the technology transfer from automotive and aerospace environment implied extensive research and testing on the application of epoxy adhesive in order to use it in a different technological environment. The design t be successful also takes into account the failure of glass parts, at the bare scale and at the overall structural scale, allowing for a safe post breaking behaviour. The control of the process, design, calculation and erection allowed to transform glass structure in an artistic element which shined in the Palais Royal arising coloured light projections on the ground taking advantage of the hexagonal shape of the bars which diffract the light thanks to the sharps edges.