Bridges have become a popular way for research groups and additive manufacturing companies to demonstrate their technologies. It makes sense. Bridges combine architecture and performance while also engaging directly with people. While not every person may recognize the ingenious nature of a topologically optimized engine component, a state-of-the art bridge can appeal to all.
Recently, a team of university students from Shanghai showcased a novel hybrid additive manufacturing approach with a futuristic metal bridge. The bridge—the Robot Fabricated Hybrid Bridge—was produced using a combination of two metal construction processes: large-scale metal 3D printing and filament winding.
In other words, the bridge was constructed in two phases. First, a metal frame was 3D printed using a robotic fabrication process. Then, to reinforce the frame, thin carbon and glass fibers were wound around the frame in a web-like fashion. The result is a metal pedestrian bridge that can safely bear over 20 people.
The structure was designed as part of the DigitalFUTURES International 2019 summer workshop at Tongji University. There, students worked in collaboration with Fab-Union, a local research studio, to design the state-of-the-art bridge using cutting edge tools like topology optimization.
Topology optimization software enabled the student team to minimize the weight of the bridge significantly without sacrificing strength. According to the team, the 11.4-meter-long bridge ended up using a total of 263 kg of steel and was 20 cm thick at its thinnest points.
The bridge itself was constructed using four robotic systems—two of each fabrication method. In the end, the bridge’s construction took only 20 days, after which the structure was transported to the installation site at the Tongji University’s College of Architecture and Urban Planning. The structure was in place for several months, but was taken down in October.
The hybrid approach presents a more cost, material and energy efficient way of manufacturing a pedestrian bridge compared to more traditional methods, such as subtractive manufacturing or casting. Moreover, because the bridge did no require any molds or formworks, the students had much more design freedom in creating the structure.
“Robotic fabrication is a high-precision manufacturing technology, combining with advanced structural analysis and optimisation method,” commented Philip F. Yuan, the architect and Tongji University researcher who led the construction. “This project proves intelligent construction has a great potential for material and energy saving in the architecture field.”
The Robot Fabricated Hybrid Bridge emphasizes the construction process and the materials used rather than the aesthetic design of the bridge itself. Still, the structure does have a unique look that is almost reminiscent of the 3Doodler’s scrawled style.