The bridge was designed to replace an existing structure over a small local canal. The structure is 3.5 meters wide and spans 6.5 meters. It consists of 3D printed elements that are rotated 90 degrees after printing, then pressed together by post-tensioned prestressing tendons.
“The need to print and stack several single elements with a hollow core by itself makes it self-evident to prestress the components to overcome the lack of bending moment resistant of unreinforced concrete; a technology commonly used in the construction industry,” the researchers state. “So, prestress tendons are placed in the openings of the printed elements, stressed, anchored at the beginning and the end, and finally released. The printed concrete elements are stressed to a level that only compression remains in the section, and no additional passive reinforcement in that direction is required.”
The cross-section of the bridge consists of a series of connected bottle shapes, alternatively positioned upside down and combined with a continuous connecting straight line at the bottom. At the front and the end of the 3D printed bridge elements, two solid concrete bulkheads, traditionally cast and reinforced, are added to introduce the pre-stress forces.
The height of each element is about 1.08 meters, or 89 to 90 layers of 12 mm each. Six elements compose the bridge. Altogether, the bridge has 582 printed layers, each 25.1 meters in length, and a total print path length of 13.4 km. To avoid brittle failure due to torsion in the bridge deck case, a reinforcement cable was introduced in the concrete “filament.” This reinforcement consists of a thin, strong steel cable that becomes embedded in the concrete during printing, thanks to a Reinforcement Embedding Device (RED) developed at TU/e.
Structural integrity was tested with a 1:2 model. A crack appeared, but it was induced by bending, rather than shear failure.
“A final full-scale test was performed in-situ to guarantee the bridge to behave as expected,” the researchers state. “The resulting deflections were too small to measure. As also no other response was observed, and in consideration of the previous material and scale testing, the bridge was considered to comply with the Dutch building regulations.”
The bridge opened to pedestrian and bicycle traffic in October of last year. This was the first 3D printed bridge that was created with the developers’ particular combination of prestressing, reinforcing and 3D printing. Additionally, it is used by regular traffic and must adhere to all local laws and regulations. It is tiny bridge, but it shows us that 3D printing can be a reliable, safe method of construction. And the bridge was only the beginning for TU/e, which is part of a new project that will be 3D printing five concrete houses in Eindhoven over the next five years. The homes will be occupied once they are completed.
Discuss this and other 3D printing topics at 3DPrintBoard.com or share your thoughts below.
Subscribe to Our Email Newsletter
Stay up-to-date on all the latest news from the 3D printing industry and receive information and offers from third party vendors.
You May Also Like
3D Printing Webinar and Event Roundup: March 17, 2024
It’s another busy week of webinars and events, including SALMED 2024 and AM Forum in Berlin. Stratasys continues its in-person training and is offering two webinars, ASTM is holding a...
Exclusive Interview: BICO’s New Bioprinting Era under Maria Forss Begins
In the dynamic landscape of life sciences, Maria Forss has taken the helm as the new CEO of BICO (STO: BICO), a name that emerged from bioprinting pioneer Cellink and...
3D Printing News Briefs, March 9, 2024: ADDiTEC Racing, 3D Printed Functional Brain Tissue, & More
In 3D Printing News Briefs, we’re starting with automotive applications, as ADDiTEC launched its new racing division. Moving on, 3D-Fuel is now part of the Nexa3D family, and researchers have...
Meet the New XJet: New CEO and CBO Discuss New 3D Printing Strategy
When it emerged on the market in 2016, Israel’s XJet was one of the most promising startups in the additive manufacturing (AM) industry. Promising a user-friendly method for producing extremely...