Double-curved, glazed gridshell covering the interior courtyard of Villers-Cotterêts castle
Project
The Renaissance castle of Villers-Cotterêts is located in the town of the same name about 80 kilometers northeast of Paris. At the initiative of the French president, the listed château was renovated from 2020 to 2023 and converted into the "Cité internationale de la langue française." As a part of the renovation and conversion, the courtyard was covered with a glazed, double-curved grid shell with a characteristic rhombic tesselation. The light and transparent shell has become the centerpiece and emblematic symbol of the castle and the Cité.
Diamond-shaped grid shell in steel and glass construction with curved insulating glass
SHELL DESIGN
The fully glazed grid shell (16x36 m) has a pitch height of just 1.3 m. The diamond-shaped grid of the supporting structure required the use of curved glass, whereby printed insulating glass with a single cylindrical curvature across the diagonal was used. The steel supporting structure as a directly glazed quadrangular net consists of single curved rectangular hollow sections with variable height and milled, massive nodes. The shell forms a statically determinate structure that transfers only minimal horizontal forces into the masonry.
Interaction of geometry, load bearing behaviour and glass cladding
STATIC ANALYSIS
Since the historic masonry cannot withstand significant lateral loads, the large thrust of the shallow shell is mitigated by transverse cables running between the longitudinal edge beams. The structural design allows the grid shell’s circumferential edge beam to appear as if it floats atop the masonry, creating an externally statically determinate structure. The cables are curved upward using hangers fixed to the shell structure to minimize their visual impact from below. The geometry of the shell is designed as a regular cylindrical barrel vault to create a uniform, continuously curved glass surface. This geometry also enabled the use of more economical singly curved thermally bent glass.
Gallery
Project data
Client CMN - Centre des Monuments Nationaux
Architect Olivier Weets Architecte
Finalization 2023
Services structural engineering, special structures
