Tests investigate behaviour of concrete flooring in fires

Researchers in the USA from the National Institute of Standards and Technology (NIST) recently built steel beam-supported concrete flooring structures and set blazes on them to collect data on how fire affects concrete flooring.

The researchers spent months constructing various structures with concrete flooring supported by steel beams, a system commonly found in high office buildings. They set the structures ablaze and then studied the cracked concrete slabs and distorted beams. Their findings on how fire affects concrete flooring supported by steel beams were published in the Journal of Structural Engineering.

Building codes normally stipulate that steel beams are sprayed with fireproof substances that slow down the rise in temperature caused by fires. To prevent the spreading of fires, sprinkler systems are installed. The local fire service is responsible for putting out the fire.

The researchers found that current fire protection strategies are enough to protect most buildings, but a minority of fires destroy property.

Some of the concrete flooring in the tests came out better than others. Floors supported by beams with double angle connections had improved performance, but the sample size was not large enough to provide definite conclusions.

The data collected by NIST on the thermal contraction and elongation of the concrete floor-supporting steel structures is now being used to build computer models that predict how new building designs resist fires. The goal is for future steel and concrete buildings to resist the full force of a major fire.