Structures Tested İn Giant Fire Test Lab

U.S. scientists studying the effects of fire on steel structures such as buildings and bridges say they've built a one-of-a-kind system to create their "fire."

Researchers at Purdue University designed a system made up of heating panels with electrical coils much like giant toaster ovens that are placed close to the surface of large steel beams and other components to simulate fire as they are subjected to forces with hydraulic equipment, a university release says.

Such testing is customarily conducted inside large furnaces.

"However, in a furnace it is very difficult to heat a specimen while simultaneously applying loads onto the structure to simulate the forces exerted during a building's everyday use," Amit Varma, an associate professor of civil engineering, said.

Building fires may reach temperatures above 1,800 degrees Fahrenheit, Varma said.

"At that temperature, exposed steel would take about 25 minutes to lose about 60 percent of its strength and stiffness," he said. "As you keep increasing the temperature of the steel, it becomes softer and weaker."

The heating system is being used to test full-scale steel columns at Purdue's Laboratory for Large-Scale Civil Engineering Research.

Each panel is about 4 feet square, and the system contains 25 panels that cover 100 square feet.

Having separate panels enables researchers to heat certain portions of specimens, recreating "the heating and cooling path of a fire event," Varma said.