A custom heating system and a specialized laboratory for testing large beams and other components are being used by researchers to create models that could be used in designs to improve fire safety.

A custom heating system and a specialized laboratory for testing large beams and other components are being used by researchers at Purdue University, West LaFayette, Ind., to create models that could be used in designs to improve fire safety.

Amit Varma, a Purdue associate professor of civil engineering, doctoral student Lisa Choe and graduate student Emily Wellman are working together on research to make structures better and safer. Data will be used to potentially update design codes for steel structures and to test and verify computational building-design models.

Building fires may reach temperatures of more than 1,800°F (~1,000°C), and the strength of steel structures drops by about 40 percent when exposed to temperatures exceeding ~930°F (500°C). Steel components in buildings are covered with fireproofing materials to resist the effects of extreme heating.

"So the air could be 1,000 degrees in a fire, but the insulated steel might be 500 degrees or less," Varma says. "However, once the steel gets beyond 600 degrees Celsius, there can be some major problems."

The Purdue researchers designed a system made up of heating panels to simulate the effects of fire and test full-scale steel columns at Purdue's Robert L. and Terry L. Bowen Laboratory for Large-Scale Civil Engineering Research.

The panels have electrical coils like giant toaster ovens, and they are placed close to surfaces being studied. As the system is used to simulate the effects of fire, test structures are subjected to forces with hydraulic equipment to mimic the loads experienced in real structures.

Varma also has led research to test a new type of design for nuclear power plants. The work focuses on testing structures like those to be used in the Westinghouse Electric Co. AP1000 standard nuclear power plant design. Engineers tested components of an "enhanced shield building" that will contain the plant's main system components.

The building consists of an inner steel-wall containment vessel and an outer radiation shield made using a technology called steel-concrete-composite construction. Instead of using more conventional reinforced concrete, which is strengthened with steel bars, the steel-concrete approach uses a sandwich of steel plates filled with concrete.

The work is funded by the National Science Foundation, the U.S. Department of Commerce's National Institute of Standards and Technology, the American Institute of Steel Construction, and the American Iron and Steel Institute.

Papers based on the research will appear in the American Society of Civil Engineers'Journal of Structural Engineering and the American Institute of Steel Construction'sEngineering Journal.

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