Lab tests structural strength against earthquakes, other natural forces

Building destroyed by earthquake

In late August, a magnitude 6.2 earthquake devastated Central Italy, killing hundreds and injuring hundreds more. The quake also demolished many structures, destroying homes and buildings of historic and cultural importance.

When it comes to earthquakes and other natural disasters, designing structures to be resilient against environmental forces can help limit the resulting damage. Researchers at the University of Minnesota’s Multi-Axial Subassemblage Testing (MAST) Lab can test how structures and building components hold up against the strain of enormous natural forces, from simulated earthquakes to tornadoes to soil pressure. The lab, originally supported for 15 years by grants through the National Science Foundation, is part of the College of Science and Engineering’s Department of Civil, Environmental and Geo-Engineering.

Mounted at the top of the MAST Lab’s testing area is a steel crosshead that precisely twists, compresses and stretches large structures through six components of movement or forces. The equipment, driven by specialized software, allows researchers to simulate the many forms of stress that building materials and components might experience not only from natural forces, but from the weight of the structure itself. The lab can test structural components nearly 30 feet tall and 20 feet wide, and exert up to 1.3 million pounds of vertical force — enough to lift an Airbus A380 jet airliner, plus its passengers and cargo, off the ground.

Arturo Schultz, Ph.D., professor of civil engineering and director of the MAST Lab, said the testing equipment is more versatile than smaller systems, allowing it to more realistically simulate what might happen in nature and gather ample data on how a tested structure performs. In fact, the lab’s capability for testing large-scale structures and applying great force to them with extreme precision make it an unparalleled resource.

“There’s no one that can do what we can do — not just in Minnesota, but in the rest of the country or even the world,” Schultz said. “It’s a very unique lab.”

Bracing against the wind

The MAST Lab isn’t just a resource for U of M research community. Over the past 10 years, researchers from universities across the country have come to the MAST Lab to test new design ideas and gather data.

Last year, the lab played an important role in an Iowa State University researcher’s project to develop a new type of wind turbine, made of precast concrete and 490 feet (150 meters) tall. Sri Sritharan, Ph.D., Wilson Endowed Engineering Professor, designed the tower to capture faster and steadier winds than traditional, steel wind towers can reach with their maximum height of around 262 feet (80 meters). Sritharan brought a 17-foot section from the bottom of his proposed tower to the MAST Lab for physical stress testing to ensure it could withstand the strain of the wind and the weight of the concrete that would sit atop it in a completed structure.

The testing, which came to a close in October 2015, proved successful. Even after weeks of fatigue testing, data suggested the tower would stay structurally sound, and Sritharan was able to set his sights toward his next goal: building a full-scale tower in the field.

ISU Hexcrete specimen in MAST lab

Iowa State researcher Sri Sritharan brought a segment of his design for a new type of wind turbine to the U of M MAST Lab to test how well it could withstand environmental stress, including the force of the wind and its own weight.

Safer structures, sooner

While the MAST Lab has typically been used by academic researchers, there are many opportunities for industry R&D experts to make use of the facility.

Industry partners can work with the lab to ensure their structural components meet rigorous quality and safety standards, as well as to gather a wealth of physical data that can help improve the design of these components. All of that could lead to shorter fabrication times, a quicker path to regulatory approval and lower construction costs.

MAST Lab projects have typically focused on testing structural components for buildings and bridges, making the facility useful for companies working in architecture, construction and structural engineering. Going forward, Schulz and his team see opportunities to expand that scope into new industries.

“We believe that there is enormous potential for a number of other applications,” he said. “The MAST Lab can inform R&D efforts in any area where operations rely on large, durable equipment and vehicles, which include industries like manufacturing, mining and oil.”

Visit the MAST Lab site to learn more or explore partnership opportunities.

2 thoughts on “Lab tests structural strength against earthquakes, other natural forces

  1. Has data gathered from research of the MAST lab been used to affect building codes, specifically
    the International Building Code as well as the ASCE Standard 7 code?

    • Thanks for your question, Rolf.

      MAST Lab Director Arturo Schultz says all MAST Lab projects have been conducted to investigate problems with either new or existing structural systems. In most cases, Schultz says, the knowledge gained from MAST testing supports the background information that accompanies proposed changes to material codes, such as the American Concrete Institute (ACI) 318 building code or the American Institute of Steel Construction (AISC) steel specification. These changes would then be adopted by IBC and ASCE 7 when the material codes are adopted.

      That said, modifying building codes is a long process. Schultz says data from a project completed today would likely take 5 to 10 years (or more) to make its way into the material codes, and even longer into IBC or ASCE 7.

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