In April 2011, a plywood gridshell sculpture was constructed at the Ramboll lead office in London. Located in the entrance foyer space, the installation was designed to implement and evaluate some of the recent research conducted by the newly launched computational design group.
Firstly, a compression shell was formfound to perfectly fill the confined boundary conditions. This was implemented using an in-house Java Script that allowed the design team to explore various designs within the constraints in real-time. Following the form-finding stage a discretisation of the continuous shell along surface curvature lines was undertaken.
The conjugate curve networks were found to be almost identical to the membrane stress principal directions allowing for both fabrication benefits and structural performance. Each member in the shell was a laser cut flat piece of 6mm FSC sourced plywood with no torsional ‘twist’ along its length due to the principal curvature orientation.
Plywood was chosen because of its low cost, appearance, sustainability credentials, ease of fabrication and compressive strength under axial load. As the members are also aligned with the principal membrane stresses the self-weight of the structure travels mostly in axial compression to the supports. The density of the member discretisation is kept constant allowing the self-weight to be similar to that of the continuous shell.
Due to each member being a constant depth, efficient nesting of the elements on each sheet of plywood was a simple task allowing for minimal material wastage during manufacture. Reference numbers are scorched onto the members to assist with assembly.