MAST: Most Amazing Structural Testing Lab!
MAST really stands for the Multi-Axial Subassembledge Testing (MAST) Laboratory. What makes it amazing is its size, power, and control.
And now, MAST’s new director, new lab manager/research associate, and two new structural faculty members are eager to take on custody of its legacy and put their own marks on this unique structural testing facility.
Front Row: MAST Director Lauren Linderman, outgoing director Catherine French, and MAST's first director Carol Shield
The laboratory facility was originally created and funded for the first 15 years by the National Science Foundation (NSF) to be run as part of the NSF George E. Brown Network for Earthquake Engineering Simulation (NEES) program. The stated purpose of the program was to operate a “network of integrated and interconnected facilities to transform earthquake engineering by integrating collaborative experimentation, computation, theory, databases, and model-based simulation.” The federal government invested $82 Million through NSF to fund 15 experimental facilities. MAST was one of those facilities.
Catherine French served as the Principal Investigator on the grant to create the facility. She worked with colleagues Carol Shield, who focused on structural control and data acquisition; Jerry Hajjar, Douglas Ernie, and David Du, who worked on telepresence features; Robert Dexter who designed the crosshead; and Arturo Schultz who worked on the building requirements.
As first proposed, the Lab was to be built within the UMN’s Civil Engineering Building by digging out additional space under Pillsbury Drive. Serendipitously, the University was able to acquire space at the edge of campus that became the location of the MAST Lab. The $6.7M grant from NSF paid for the testing equipment, which included construction of the strong floor and strong walls of the lab. The University paid to build the shell walls and office space around the testing floor.
The unique equipment of the lab was built by MTS Systems. Carol Shield, the first Lab Director said at that time, “We sought to be the first facility capable of performing highly accurate tests on full-scale civil structural specimens, including the ability to apply loads realistically in multiple axes.…We knew it would be a formidable task to test such enormous specimens. That’s why we chose to work with MTS.”
Directors
Carol Shield was the Director for over ten years while the Lab was part of NEES. As part of the NEES collaborative, the lab needed to be available to researchers who were awarded an NSF grant to use the laboratory. Through that time, MAST was occupied at 100% capacity.
The large projects at MAST take a great amount of time, from planning to constructing a specimen, testing, and then de-constructing the “dead” specimen. Once a specimen is built, it can take a month before it is ready to test. Some of the more time-consuming tasks include setting sensors and moving a large specimen into the MAST test bay. At each step, meticulous monitoring and documentation is needed.
An important part of Shield’s legacy was the establishment of best practices for managing and sharing this unique testing facility. Shield had set up a similar process for CEGE’s Theodore V. Galambos Structural Laboratory, which is located within the Civil Engineering Building. The NSF NEES Network adopted the model developed by Shield to manage and coordinate the other facilities. Arturo Schultz took over as Director of MAST for a short period following the NEES era, during his time MAST’s hybrid testing capabilities were upgraded.
Catherine French took the reins from 2018 to 2023. During her time as director, the hybrid testing capabilities were further upgraded by MTS and now include cascade control, which can be used to test very stiff specimens where small imposed displacements could induce very large forces. French worked to keep the MAST Lab continuously occupied through contract testing and sponsored projects research.
This year, French is transitioning into retirement, and Lauren Linderman has taken over as the Director of the MAST and Galambos structural laboratories. Linderman’s research is focused on developing effective monitoring and control strategies to sustain the long-term performance of civil structures under routine operation and extreme events. Her primary areas of interest include structural monitoring, vibration mitigation strategies, wireless sensor systems, and data acquisition techniques. These research efforts combine lab-scale experiments and field studies with fundamental concepts in control theory, structural behavior, and wireless systems.
Research Faculty
Three recent hires were drawn to UMN by the power of the MAST Lab: a new laboratory manager/research associate and two new faculty with expertise in large-scale structural testing.
Steven Barbachyn (Ph.D., Notre Dame), Lab Manager and Research Associate, had been a client at MAST before joining the University staff. In 2023, Barbachyn led a project for GE that involved testing a large, 3D-printed concrete structure.
Pedram Mortazavi (Ph.D., University of Toronto) had worked in large structural testing and hybrid simulation at the University of Toronto. He, like most researchers active in large-scale testing, was aware of the MAST Lab. His thesis adviser had visited the MAST Lab and told Mortazavi it would be a great place for him as a large-scale testing expert. But Mortazavi was not prepared for what he saw when he walked into MAST. “Words, pictures, and videos do not do it justice. It is hard to fully grasp how big it is until you walk in here,” he said. Mortazavi is excited for the opportunity to leverage the capabilities of the MAST Lab to further advance his research.
Ben Worsfold (Ph.D., University of California Berkely) heard of the MAST Lab while at Berkeley, where he had worked with a one-dimensional setup for testing structures. In addition to the size, force, and degrees of freedom in the system, Worsfold is especially impressed with the ease of constraining out-of- plane motion, which is a challenge in a one-dimensional testing facility.
Paired with the MAST Lab at UMN is the Theodore V. Galambos Structural Laboratory, located in the Civil Engineering Building. That lab is well suited for large-scale testing of long span structures, such as bridge girders and other structures that do not require the MAST Lab capabilities. The Galambos Lab features a universal testing machine capable of applying 600,000 pounds in compression. A new data acquisition system (DAQ), hydraulic control system, and upgrades to actuators have been ordered to increase that lab’s capabilities and efficiency and allowing for hybrid simulation testing. Worsfold will soon be setting up the first experiment on the new equipment to test ultra-high performance concrete girders.
Future
Director Linderman is positive about the future for these labs. She notes that large-scale experiments are still needed because computer modeling, while advancing rapidly, cannot replace the need for testing. She draws an example from her interest in Formula One Racing. “Every few years they change the specifications, and the cars need to be redeveloped. That industry has the finest designers, finest engineers, and the finest testing equipment. Yet on the first run, you still see parts flying off the newly designed cars. To me, that shows that modeling has not yet been perfected and speaks to the continuing need for large-scale, physical experiments.”
The MAST Lab is a valuable resource with extensive opportunities for real-world, large-scale structural experiments to test new materials, validate models, and test components for remediation or retrofit in existing structures. And the MAST researchers are dreaming big!
You can support work of the MAST Lab by giving directly at https://z.umn.edu/ GivetoMASTLab or contact Contact Shannon Wolkerstorfer (External Relations) at [email protected] for more information.
The Building
The laboratory, located east of Huntington Bank Stadium, was built to test large structural components or models. It has strong walls and a strong floor to accommodate the forces and weight required for such large-scale testing. Three main areas make up the testing space: staging, testing, and control.
The Staging Area allows large samples to be built, assembled, or delivered.
Once the sample is ready, it is moved into the Testing Area. Mounted at the top of the MAST Lab’s testing area is a steel crosshead that can precisely twist, compress, or stretch large samples with six degrees of freedom. Researchers can simulate many forms of stress to test building components or materials.
UMN’s MAST Lab is able to handle specimens 18 to 35 feet high and 20x20 feet in-plane; longer test specimens can be placed at a diagonal. One of the key features of the equipment is the hydraulic bearings, the largest of their kind designed by MTS. The bearings make it possible to apply large axial loads to test specimens while exhibiting minimal friction in the bearings when imposing loading in the horizontal directions. Without this feature, it would be nearly impossible to know the amount of horizontal force going into the test structure versus the force necessary to overcome friction in the bearings.
The testing mechanism is run from a Control Room with windows facing the testing floor. The equipment is driven by specialized software developed by MTS with collaboration from Professor Emerita Carol Shield, who served as the Director of the laboratory through more than the first decade of its operation. In addition, the facility has impressive data collection capabilities and a large data repository from its days as a NEES facility.