How much length will unprotected steel expand for each 100°F rise in temperature?

When steel is subjected to an increase in temperature, it experiences thermal expansion, which results in a proportional increase in length. The general coefficient of linear expansion for steel is approximately 0.000006, or 6 x 10^-6 per degree Fahrenheit. When calculating how much steel will expand for a rise of 100°F, the formula for linear expansion can be applied:

Expansion = original length × coefficient of linear expansion × temperature change.

For a 100°F increase, the expansion factor would be:

Expansion = original length × 0.000006 × 100 = original length × 0.0006.

When expressed as a percentage of the original length, this results in around 0.06% for every 100°F increase. Therefore, the correct choice of 0.06 to 0.07% accurately reflects the typical expansion rate of unprotected steel as temperatures rise. Understanding this principle is essential for fire service personnel, as it can impact the structural integrity of buildings during thermal events.