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Aug 20, 2023

spiral staircase wraps around the sculptural 3dpod in tokyo

Obayashi design group constructs ‘3dpod’, the first earthquake-proof, certified building in Japan to be 3D printed . Fabricated with a special printing mortar acting as a formwork, the frame sets up

Obayashi design group constructs ‘3dpod’, the first earthquake-proof, certified building in Japan to be 3D printed. Fabricated with a special printing mortar acting as a formwork, the frame sets up high-strength concrete mixed with steel fibers, not requiring the use of conventional reinforcing bars. All structural elements above ground are generated with 3D-printing technology, including the walkable-roof slab and stairs, while insulation and full MEP equipment are integrated into ad-hoc wall cavities.

The demonstration facility, open to the public, is built to evaluate the durability, structural, and environmental performance of 3d-printing, and to foster further its technological development. With architectural 3D printing being particularly challenging in earthquake-prone Japan, and, due to building regulation restrictions, the technique has so far been employed only in civil engineering and non-habitable, small structures. The project aims for a contemporary design that meets the strict local requirements without relying on conventional reinforcement.

3dpod is framed by the surrounding cherry blossoms | all images by Satoshi Shigeta unless stated otherwise

The team at Obayashi applies a special mortar to print 3dpod that acts both as an internal and external finishing surface as well as the framework for the load-bearing structure, made of a high-strength concrete reinforced with steel fibers, called ‘SLIM-Crete®’. This construction method does not require the placement of reinforcing bars or steel frames, not to limit the aesthetic potential of 3D printing. The pod-like shape is derived by maximizing the ratio between interior space and wall-surface area, achieving the largest internal volume with the least amount of material, given the technical printing constraints and the limitations of the site. The walls are multi-layered, combining load-bearing structure and cavities for insulating material, equipment routing, and a system for radiant heating and cooling, to afford the level of habitability of a conventional building.

3dpod stands adjacent to the Obayashi Technology Research Institute’s forest

The slab design features strengthening ribs following principal stress lines, a means of material economy achieving aesthetic and spatial qualities at the same time. This outcome would have been unfeasible using conventional construction methods. To fabricate 3dpod, a robotic printer is installed on-site, printing the mortar formwork directly onto the foundations. The roof-slab formwork is instead printed as a precast element at a nearby facility, then placed on top of the walls and capped with SLIM-Crete®, creating a shell structure. Thereafter, the 3D printer is placed on the roof slab to finish off the parapet of the walkable deck, demonstrating the technical feasibility of a multi-storied printed building.

The project which is the result of cutting-edge digital fabrication, manages to retain a certain warmth and haptic appeal. The unique texture emerging from on-site construction methods, reminiscent of hand-crafted work allows for an appealing roughness and primitive aura. Architectural 3D printing can reduce labor demand on the construction site, shorten construction time through automation, and save on CO2 emissions, thanks to reduced transportation of building materials. Obayashi’s design team advances the development of 3D printing in the AEC industry, targeting the chronic shortage of skilled workers and construction issues in remote areas, all the while promoting the diversification of building materials, and aiming for a localized construction process.

the interplay of light and shadow reveals the sculptural qualities of 3dpod

on-site printed brackets support the precast, 3D-printed stair treads