Fig. 1 Trusswall Arrangement: The catenoid defines its geometry with 13,400 limbs of reinforcing bars (Trusswall) which are arranged in two different ways: radiant and parallel. We assigned the parallel arrangement more frequently in order to simplify the process and to achieve high precision and efficiency of the construction.
The catenoidal structures of the National Taichung Theatre unfold their space both vertically and laterally, forming the continuous interior space-tubes for the theatrical venue — named ‘Sound Caves’. Our design theme for this building was, from the planning to construction period, to conceive of the structural and mechanical arrangement along the catenoid that simultaneously maintains the spatial continuity.
Fig. 2 Trusswall Arrangement & Unit Division: The parallel arrangement of the Trusswall makes up more than 70%, while the radial arrangement is minimised to alleviate the construction difficulty. The catenoid is then divided into approximately 1,200 units that are deliverable on trucks.
While we were designing this building, we repeatedly resorted to digital technology to analyse the unique structure. At the same time, we built physical models to validate its construction feasibility, which we could not visualise in the drawings. When the construction began, the discussion with the local contractor offered yet more specific and efficient construction methodologies. Integrating such information, the drawings became media that we updated every day to examine its geometrical conformity to the other systems, such as design, structure, electrical, air conditioning, mechanical, fire protection, and theatre equipment.
Fig. 3 Coordinates of Trusswall on Catenoid: 58 point coordinates of the catenoid are displayed on the digital model, maintaining precision in the construction. These coordinates are laser-measured on the construction site, and contributed to building the highly precise 3D curvatures that deviated only ±30mm.
All the architectural, structural, and mechanical drawings were thus optimised and were delivered to craftsmen. Ten years after the design phase, seven years after the groundbreaking, the building marked the official completion. We learned through this unique project that our direct discussion on the job site clarified the issues and offered the solutions more often than merely pointing out the problems on the drawings. As the drawings even came to include the instructions for the construction, we ultimately noticed that what was needed to achieve the smartly represented digital model and (quasi-)organised drawings was rather the repetition of steady discussions and patient manual works.
– Toyo Ito & Associates, Architects (translated by Ryosuke Imaeda)
Fig. 4 3F Plan: The third-floor plan showing the Grand Theatre on the right, Playhouse on the left, and the foyer in between. The structural elements, electrical, air conditioning, mechanical, and fire protection systems are carefully arranged in order to avoid visual interference for the audience, offering a unique theatrical space that befits the National Theatre.