A 3D-printed steel footbridge has been unveiled by a robot in Amsterdam where it will serve as a ‘living laboratory’ to assess the long-term behaviour of metal printed structures.

The world’s first 3D-printed steel structure has been developed by Imperial College London and The Alan Turing Institute and built over four years by Dutch company MX3D.

The pedestrian bridge is packed with a network of sensors that will be used by Imperial College London researchers to measure, monitor and analyse the performance of the novel 12-metre-long structure as pedestrians pass over it.

According to Imperial, data collected will enable researchers and engineers to measure the bridge’s ‘health’ in real time, monitor how it changes over its lifespan and understand how the public interacts with 3D-printed infrastructure.

Sensor network to turn additive bridge into ‘living laboratory’

Data from the sensors will also be put into a ‘digital twin’ of the bridge, which will help answer questions about the long-term behaviour of 3D-printed steel, as well as its use in real world settings and in future novel construction projects.

To get from the conceptual stage to the installed footbridge, the Steel Structures group at Imperial conducted the underpinning research and validation, including testing destructive forces on printed elements, advanced digital twin computer simulations, non-destructive real-world testing on the footbridge and the development of the advanced sensor network to monitor the bridge’s behaviour over its life.

Imperial co-contributor Professor Leroy Gardner of the Department of Civil and Environmental Engineering said: “A 3D-printed metal structure large and strong enough to handle pedestrian traffic has never been constructed before. We have tested and simulated the structure and its components throughout the printing process and upon its completion, and it’s fantastic to see it finally open to the public.”

Dr Craig Buchanan, also of the Department of Civil and Environmental Engineering, added: “We look forward to continuing this work as the project transitions from underpinning research to investigating the long-term behaviour of metal printed structures. Research into this new technology for the construction industry has huge potential for the future, in terms of aesthetics and highly optimised and efficient design, with reduced material usage. It has been fascinating and we are delighted that the structure is now ready to be used.”

The bridge was installed over the Oudezijds Achterburgwal canal in Amsterdam and was unveiled by a robot today (July 15, 2021).

3D-printed steel footbridge
Image: Adriaan de Groot

The testing work was led by Professor Gardner and Dr Buchanan, supported by undergraduate and postgraduate students, PhD candidates, post-doctoral researchers and laboratory technicians. The team’s work was predominantly funded by The Alan Turing Institute, with additional funding from EPSRC.

The Steel Structures group undertook their research programme using small-scale destructive material and cross-section testing, computer modelling and large-scale non-destructive real-world testing on the footbridge.

“3D printing presents tremendous opportunities to the construction industry, enabling far greater freedom in terms of material properties and shapes,” Professor Gardner said in a statement, “This freedom also brings a range of challenges and will require structural engineers to think in new ways.”

Dr Buchanan said: “For over four years we have been working from the micrometre scale, studying the printed microstructure up to the metre scale, with load testing on the completed bridge. This challenging work has been carried out in our testing laboratories at Imperial, and during the construction process on site in Amsterdam and Enschede, the Netherlands, on the actual printed bridge.”

The data captured from the 3D-printed steel footbridge will be made available to other researchers worldwide who want to work with the Turing researchers in analysing the data.