PHOTO: The first stop made of digital concrete in the Czech Republic! DPP uses 3D printing technology

The Prague City Transport Company (Dopravní podnik hl. m. Prahy - DPP) is using a new digital printing system at the boarding stop of tram line 12 at the oldest Výstaviště stop. In cooperation with the Prague City Hall, and the company So Concrete, the first shelter in the Czech Republic made with the technology of robotic 3D printing of ultra-high-strength concrete (UHPC) was put into operation. The production of the individual parts of the shelter took only 36 hours and took place in the workshops of So Concrete in Prague 7. The shelter has dimensions of 2.5 x 8 meters, a height of 3 meters, a weight of 2 tonnes, and is equipped with a bench also made by 3D printing and an LCD information panel.

The unique shelter is composed of several structural segments, for the production of which different types of concrete and 3D printing approaches were used. The roof and passenger bench are made using robotic 3D printing. The type of concrete was chosen by the manufacturer according to the function and load of the segment. For example, dispersed steel wire reinforcement was not used for the bench seating area, as opposed to the roof, which includes this reinforcement. To produce the column heads, the robot milled and printed the molds into which the final heads were then cast in concrete.

The design of the shelter uses the natural principles of internal force distribution, i.e., pressures and pulls, making the resulting design not only unique but, above all, maximally efficient. Compared to conventional technologies, this approach saves up to 60% of the material with minimal human labor. The physical and technical properties of ultra-high-strength concrete make it possible to produce such subtle self-supporting structures using a minimum amount of steel. Robotic 3D printing not only brings the advantage of saving human labor but also the ability to produce such complex shapes in an extremely short time without the need for molds or formwork. From both an economic and sustainability perspective, robotic 3D printing of high-strength concrete can therefore be considered the technology of the future.

"Within the City of Prague, we like to try new materials and modern technologies. One of them is high-strength concrete, which we are using in the construction of the Štvanická footbridge, the reconstruction of the Barrandov Bridge, and we are going to use it also in the reconstruction of the Libeň Bridge," said Adam Scheinherr, Deputy Mayor of the City of Prague. He is also the chairman of the Supervisory Board of DPP.

"Within the tram infrastructure, we have several activities developed with our partners using the latest technologies and scientific knowledge that could be summarised under the heading of smart city projects. The opportunity to cooperate on a project of a bus stop shelter made with 3D printing attracted us for many reasons. Firstly, because of the use of a commonly available but unconventional material for the shelter with minimal use of steel, which is currently in short supply, then because of the overall material savings, maintenance-free, but also incredibly quick and easy implementation and the countless possibilities to customize the design and produce a shelter that would be specific to the chosen location. It will be interesting to see the effect of external and climatic factors on the shelter. We did not choose the Výstaviště stop for the installation by chance. It is a long-neglected site where we are preparing a comprehensive reconstruction of the tram line, following the reconstruction of the bridge by the Railway Administration, a state organization. Now our plan is being discussed with state and local government authorities, which will result in, among other things, the addition of barrier-free stops," said Jan Šurovský, member of the board of directors and technical director of DPP - Povrch.

So Concrete started preparing the project for this shelter in cooperation with DPP last year. "We use this framework to design our own software tools, which cover processes ranging from geometry generation, topological optimization, static analysis, 3D slicers, and inverse kinematic solvers to post-processing. Our focus on creating custom digital solutions allows us to quickly adapt to a wide range of standard file formats and geometry types. Working closely with our customers to optimize the input digital models for our manufacturing process allows us to move quickly from idea to physical object," explains Dmitry Nikitin, Robotics Engineer at So Concrete, explaining the design process.

The design of the tram shelter follows the natural principles

The parametric design of the tram shelter is based on natural principles, especially in the area of force distribution and traction. The shape of the tram stop, the location, and shape of the ribs, and the columns, all make the most of the efficiency of nature's proven solutions. "We analyze the structure statically during the design process and then use topological optimization to reduce the volume of material used. The aesthetic qualities and structural requirements are maintained. The resulting morphology of the ribs reflects the actual behavior of the structure under load and thus directly shows the forces that take place within it. Thanks to the optimization, we were then able to remove areas with less usability from the structure and save up to 60% of the material. The result is a perforated fine structure that can withstand the same load as a full concrete slab," comments Záviš Unzeitig, designer at So Concrete, explaining the design process.

What is digital concrete?

State-of-the-art digital techniques and processes allow concrete to be used in new ways that help build structures and infrastructure more efficiently and cost-effectively. Recent developments show that new inventions, such as 3D printing of concrete structures and forms, are not only possible but likely to dominate construction technology in the coming years. 

3D printing, in particular, has the potential to produce building elements with complex shapes. It can be achieved either by printing individual components or creating molds that allow the desired structures to be more sculpted and refined. Automated manufacturing is boosting off-site production, which is seen as key to increasing productivity across the construction sector. Concrete elements such as floors and walls are produced in controlled conditions in factories using digital technology, then transported and quickly assembled on site. It reduces construction time, saves costs, and promotes sustainability.

 

Source: Dopravní podnik hl. m. Prahy