Here’s the problem: the Army needs a building or bridge for a forward-deployment mission in another country. Shipping a full-scale structure or building materials may not be an option, especially if the mission is in a conflict zone.
That’s the basis of a current research project led by Civil & Environmental Engineering Assistant Professor Floriana Petrone and Associate Research Professor Sherif Elfass in collaboration with the U.S. Army Engineer Research and Development Center (ERDC) Construction Engineering Research Laboratory (CERL) and supported by the U.S. Department of Defense.
Petrone and her team are focusing on the integrity and performance of structures built using 3D-printed LEGO-like concrete modules. The team’s experimental program, which began in early 2024, involves testing “bridging infrastructure” they have assembled with 3-foot-long concrete modules they have printed. The bridge was tested and numerically simulated— a computational technique to simulate and analyze real-world systems through mathematical models — to validate the experiments.
“We are following a structured approach,” Petrone said, “introducing rigor in the way we approach the printing.”
Early work in 3D-printed structures has necessarily been conducted in a trial-and-error — or Edisonian — style, but the University of Nevada, Reno is perfecting a more precise way to test 3D-printed structures.
This work aims to advance the Army’s ability to construct needed infrastructure in a conflict zone or area where military operations are taking place. Petrone’s project differs from many others in this area in that it combines 3D-printing, segmental construction — building large structures by assembling smaller components — and advanced numerical simulation. Together, these provide a basis for building reliably sound, scalable structures.
Commencing compression test …
In a corner of the Large-Scale Structures Laboratory (LSSL) on the University’s campus, Petrone and team have been 3D-printing concrete components in the shape of Ls and Ts using a mid-scale 3D printer from the U.S. Army.
This fall, the team gathered in the same lab for a load test: about seven concrete segments held together with post-tensioned cable running through the center of the components underwent an increasing amount of load. This narrow section of “bridge” took up to 7,000 pounds of load.
“We’re very pleased with this,” Elfass said, referring to the bridge performance.
Sensors attached to the components gathered data that will be used for the analyses and numerical simulation done by postdoctoral scholar Satish Paudel and undergraduate researcher Allen Rivas.
One of the next steps, Petrone said, will be to widen the test sample by adding additional components and investigate connections for accelerated construction. The project is funded through June 2025.
Providing a solid technical basis
The ultimate project objective, Petrone said, is to provide the Army with a solid technical basis on how to print and assemble needed structures in the field. She and her team have kept this mission in mind throughout the project, thinking through processes such as how the 3D-printed components will be connected to each other. In the case of their current project, the components connect to each other with cables that don’t need specialized equipment.
“Everything could be assembled manually on site,” Petrone said about the cabling system, because specialized equipment may not be available in a combat zone.
Structures theoretically could be disassembled into their component parts when they no longer are needed and reassembled into different configurations. Printing identical structural components enables highly adaptable designs, according to Elfass, and the research he and Petrone are conducting will help engineers in the field connect those components in a way that produces structurally sound infrastructure.
“The integration of numerical modeling with 3D printing and segmental construction provides a powerful tool for predicting structural performance before construction even begins,” Elfass wrote. “This allows engineers to optimize the placement of segments and the design of printed components, ensuring that printed structures meet the necessary strength and durability requirements in a variety of conditions.”
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