The request was to build an ephemeral auditorium for the FADfest 2017 edition, providing the necessary infrastructure to celebrate 4 consecutive days of events with a total seating capacity of 900 people.
Given the time and budget constraints, the constructive solution adopted was a doubly curved gridshell elastically formed from a flat grid of straight tubes. The location within an emptied lake for this occasion, determined that the structure had to be suspended from the crane used during erection.
The grid was made with standard tubular GFRP profiles connected with rotating joints from a scaffolding system. Above the grid of tubes, a tailored membrane guarantees the weatherproof and light control required by audiovisual content.
The final form came through a form-finding process, in which it was the material itself that computed the form. The main challenge was to find numerically and accurately, the stress state and final form that acquired the structure by self-weight, designing only the lengths of the cables.
The project was developed entirely at CODA office and was possible thanks to the integration of the calculation methods in a parametric modeling environment. The simulation was performed comparing two methods of nonlinear analysis: on the one hand dynamic relaxation (Grasshopper - kangaroo2) and on the other, the matrix method (Wintess, developed by the partner Ramon Sastre). Both methods were calibrated with laboratory break tests.